|United States of America|
|Motto: In God We Trust (official)
E Pluribus Unum (traditional)
(Latin: Out of Many, One)
|Anthem: "The Star-Spangled Banner"
|Largest city||New York City|
|Official language(s)||None at federal level[a]|
|National language||English (de facto)[b]|
|Government||Federal constitutional presidential republic|
|-||President||Barack Obama (D)|
|-||Vice President||Joe Biden (D)|
|-||Speaker of the House||Nancy Pelosi (D)|
|-||Chief Justice||John Roberts|
|Independence from the Kingdom of Great Britain|
|-||Declared||July 4, 1776|
|-||Recognized||September 3, 1783|
|-||Current constitution||June 21, 1788|
|-||Total||9,826,675 km2 [c](3rd/4th)
3,794,101 sq mi
|-||2010 estimate||308,884,000 (3rd[d])|
|GDP (PPP)||2008 estimate|
|-||Total||$14.441 trillion (1st)|
|-||Per capita||$47,440 (6th)|
|GDP (nominal)||2008 estimate|
|-||Total||$14.441 trillion (1st)|
|-||Per capita||$47,440 (17th)|
|Gini (2007)||45.0 (44th)|
|HDI (2007)||▲ 0.956 (very high) (13th)|
|Currency||United States dollar ($) (
|Time zone||(UTC−5 to −10)|
|-||Summer (DST)||(UTC−4 to −10)|
|Date formats||m/d/yy (AD)|
|Drives on the||right|
|Internet TLD||.us .gov .mil .edu|
|^ a. English is the official language of at least 28 states—some sources give a higher figure, based on differing definitions of "official". English and Hawaiian are both official languages in the state of Hawaii.
^ c. Whether the United States or the People's Republic of China is larger is disputed. The figure given is from the U.S. Central Intelligence Agency's World Factbook. Other sources give smaller figures. All authoritative calculations of the country's size include only the 50 states and the District of Columbia, not the territories.^ d. The population estimate includes people whose usual residence is in the fifty states and the District of Columbia, including noncitizens. It does not include either those living in the territories, amounting to more than 4 million U.S. citizens (most in Puerto Rico), or U.S. citizens living outside the United States.
The United States of America (commonly referred to as the United States, the U.S., the USA, or America) is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to the east and Russia to the west across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories in the Caribbean and Pacific.
At 3.79 million square miles (9.83 million km2) and with about 309 million people, the United States is the third or fourth largest country by total area, and the third largest both by land area and population. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The U.S. economy is the largest national economy in the world, with an estimated 2008 gross domestic product (GDP) of US $14.4 trillion (a quarter of nominal global GDP and a fifth of global GDP at purchasing power parity).
Indigenous peoples of Asian origin have inhabited what is now the mainland United States for many thousands of years. This Native American population was greatly reduced by disease and warfare after European contact. The United States was founded by thirteen British colonies located along the Atlantic seaboard. On July 4, 1776, they issued the Declaration of Independence, which proclaimed their right to self-determination and their establishment of a cooperative union. The rebellious states defeated the British Empire in the American Revolution, the first successful colonial war of independence. The Philadelphia Convention adopted the current United States Constitution on September 17, 1787; its ratification the following year made the states part of a single republic with a strong central government. The Bill of Rights, comprising ten constitutional amendments guaranteeing many fundamental civil rights and freedoms, was ratified in 1791.
In the 19th century, the United States acquired land from France, Spain, the United Kingdom, Mexico, and Russia, and annexed the Republic of Texas and the Republic of Hawaii. Disputes between the agrarian South and industrial North over states' rights and the expansion of the institution of slavery provoked the American Civil War of the 1860s. The North's victory prevented a permanent split of the country and led to the end of legal slavery in the United States. By the 1870s, the national economy was the world's largest. The Spanish–American War and World War I confirmed the country's status as a military power. It emerged from World War II as the first country with nuclear weapons and a permanent member of the United Nations Security Council. The end of the Cold War and the dissolution of the Soviet Union left the United States as the sole superpower. The country accounts for two-fifths of global military spending and is a leading economic, political, and cultural force in the world.
In 1507, German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere "America" after Italian explorer and cartographer Amerigo Vespucci. The former British colonies first used the country's modern name in the Declaration of Independence, the "unanimous Declaration of the thirteen united States of America" adopted by the "Representatives of the united States of America" on July 4, 1776. The current name was finalized on November 15, 1777, when the Second Continental Congress adopted the Articles of Confederation, which states, "The Stile of this Confederacy shall be 'The United States of America.'" The short form the United States is also standard. Other common forms include the U.S., the USA, and America. Colloquial names include the U.S. of A. and the States. Columbia, a once popular name for the United States, was derived from Christopher Columbus. It appears in the name "District of Columbia".
The standard way to refer to a citizen of the United States is as an American. Though United States is the formal adjective, American and U.S. are the most common adjectives used to refer to the country ("American values," "U.S. forces"). American is rarely used in English to refer to people not connected to the United States.
The phrase "the United States" was originally treated as plural—e.g., "the United States are"—including in the Thirteenth Amendment to the United States Constitution, ratified in 1865. It became common to treat it as singular—e.g., "the United States is"—after the end of the Civil War. The singular form is now standard; the plural form is retained in the idiom "these United States".
The land area of the contiguous United States is approximately 1.9 billion acres (770 million hectares). Alaska, separated from the contiguous United States by Canada, is the largest state at 365 million acres (150 million hectares). Hawaii, occupying an archipelago in the central Pacific, southwest of North America, has just over 4 million acres (1.6 million hectares). After Russia and Canada, the United States is the world's third or fourth largest nation by total area, ranking just above or below China. The ranking varies depending on how two territories disputed by China and India are counted and how the total size of the United States is calculated: the CIA World Factbook gives 3,794,101 square miles (9,826,675 km2), the United Nations Statistics Division gives 3,717,813 sq mi (9,629,091 km2), and the Encyclopædia Britannica gives 3,676,486 sq mi (9,522,055 km2). Including only land area, the United States is third in size behind Russia and China, just ahead of Canada.
The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountains divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest. The Mississippi–Missouri River, the world's fourth longest river system, runs mainly north–south through the heart of the country. The flat, fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast. The Rocky Mountains, at the western edge of the Great Plains, extend north to south across the country, reaching altitudes higher than 14,000 feet (4,300 m) in Colorado. Farther west are the rocky Great Basin and deserts such as the Mojave. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast. At 20,320 feet (6,194 m), Alaska's Mount McKinley is the tallest peak in the country and in North America. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands, and Hawaii consists of volcanic islands. The supervolcano underlying Yellowstone National Park in the Rockies is the continent's largest volcanic feature.
The United States, with its large size and geographic variety, includes most climate types. To the east of the 100th meridian, the climate ranges from humid continental in the north to humid subtropical in the south. The southern tip of Florida is tropical, as is Hawaii. The Great Plains west of the 100th meridian are semi-arid. Much of the Western mountains are alpine. The climate is arid in the Great Basin, desert in the Southwest, Mediterranean in coastal California, and oceanic in coastal Oregon and Washington and southern Alaska. Most of Alaska is subarctic or polar. Extreme weather is not uncommon—the states bordering the Gulf of Mexico are prone to hurricanes, and most of the world's tornadoes occur within the country, mainly in the Midwest's Tornado Alley.
The U.S. ecology is considered "megadiverse": about 17,000 species of vascular plants occur in the contiguous United States and Alaska, and over 1,800 species of flowering plants are found in Hawaii, few of which occur on the mainland. The United States is home to more than 400 mammal, 750 bird, and 500 reptile and amphibian species. About 91,000 insect species have been described. The Endangered Species Act of 1973 protects threatened and endangered species and their habitats, which are monitored by the United States Fish and Wildlife Service. There are fifty-eight national parks and hundreds of other federally managed parks, forests, and wilderness areas. Altogether, the government owns 28.8% of the country's land area. Most of this is protected, though some is leased for oil and gas drilling, mining, logging, or cattle ranching; 2.4% is used for military purposes.
The indigenous peoples of the U.S. mainland, including Alaska Natives, are most commonly believed to have migrated from Asia. They began arriving at least 12,000 and as many as 40,000 years ago. Some, such as the pre-Columbian Mississippian culture, developed advanced agriculture, grand architecture, and state-level societies. After Europeans began settling the Americas, many millions of indigenous Americans died from epidemics of imported diseases such as smallpox.
In 1492, Genoese explorer Christopher Columbus, under contract to the Spanish crown, reached several Caribbean islands, making first contact with the indigenous people. On April 2, 1513, Spanish conquistador Juan Ponce de León landed on what he called "La Florida"—the first documented European arrival on what would become the U.S. mainland. Spanish settlements in the region were followed by ones in the present-day southwestern United States that drew thousands through Mexico. French fur traders established outposts of New France around the Great Lakes; France eventually claimed much of the North American interior, down to the Gulf of Mexico. The first successful English settlements were the Virginia Colony in Jamestown in 1607 and the Pilgrims' Plymouth Colony in 1620. The 1628 chartering of the Massachusetts Bay Colony resulted in a wave of migration; by 1634, New England had been settled by some 10,000 Puritans. Between the late 1610s and the American Revolution, about 50,000 convicts were shipped to Britain's American colonies. Beginning in 1614, the Dutch settled along the lower Hudson River, including New Amsterdam on Manhattan Island.
In 1674, the Dutch ceded their American territory to England; the province of New Netherland was renamed New York. Many new immigrants, especially to the South, were indentured servants—some two-thirds of all Virginia immigrants between 1630 and 1680. By the turn of the century, African slaves were becoming the primary source of bonded labor. With the 1729 division of the Carolinas and the 1732 colonization of Georgia, the thirteen British colonies that would become the United States of America were established. All had local governments with elections open to most free men, with a growing devotion to the ancient rights of Englishmen and a sense of self-government stimulating support for republicanism. All legalized the African slave trade. With high birth rates, low death rates, and steady immigration, the colonial population grew rapidly. The Christian revivalist movement of the 1730s and 1740s known as the Great Awakening fueled interest in both religion and religious liberty. In the French and Indian War, British forces seized Canada from the French, but the francophone population remained politically isolated from the southern colonies. Excluding the Native Americans (popularly known as "American Indians"), who were being displaced, those thirteen colonies had a population of 2.6 million in 1770, about one-third that of Britain; nearly one in five Americans were black slaves. Though subject to British taxation, the American colonials had no representation in the Parliament of Great Britain.
Tensions between American colonials and the British during the revolutionary period of the 1760s and early 1770s led to the American Revolutionary War, fought from 1775 through 1781. On June 14, 1775, the Continental Congress, convening in Philadelphia, established a Continental Army under the command of George Washington. Proclaiming that "all men are created equal" and endowed with "certain unalienable Rights," the Congress adopted the Declaration of Independence, drafted largely by Thomas Jefferson, on July 4, 1776. That date is now celebrated annually as America's Independence Day. In 1777, the Articles of Confederation established a weak confederal government that operated until 1789.
After the British defeat by American forces assisted by the French, Great Britain recognized the independence of the United States and the states' sovereignty over American territory west to the Mississippi River. A constitutional convention was organized in 1787 by those wishing to establish a strong national government, with powers of taxation. The United States Constitution was ratified in 1788, and the new republic's first Senate, House of Representatives, and president—George Washington—took office in 1789. The Bill of Rights, forbidding federal restriction of personal freedoms and guaranteeing a range of legal protections, was adopted in 1791.
Attitudes toward slavery were shifting; a clause in the Constitution protected the African slave trade only until 1808. The Northern states abolished slavery between 1780 and 1804, leaving the slave states of the South as defenders of the "peculiar institution." The Second Great Awakening, beginning about 1800, made evangelicalism a force behind various social reform movements, including abolitionism.
Americans' eagerness to expand westward prompted a long series of Indian Wars and an Indian removal policy that stripped the native peoples of their land. The Louisiana Purchase of French-claimed territory under President Thomas Jefferson in 1803 almost doubled the nation's size. The War of 1812, declared against Britain over various grievances and fought to a draw, strengthened U.S. nationalism. A series of U.S. military incursions into Florida led Spain to cede it and other Gulf Coast territory in 1819. The United States annexed the Republic of Texas in 1845. The concept of Manifest Destiny was popularized during this time. The 1846 Oregon Treaty with Britain led to U.S. control of the present-day American Northwest. The U.S. victory in the Mexican–American War resulted in the 1848 cession of California and much of the present-day American Southwest. The California Gold Rush of 1848–49 further spurred western migration. New railways made relocation easier for settlers and increased conflicts with Native Americans. Over a half-century, up to 40 million American bison, or buffalo, were slaughtered for skins and meat and to ease the railways' spread. The loss of the buffalo, a primary resource for the plains Indians, was an existential blow to many native cultures.
Tensions between slave and free states mounted with arguments over the relationship between the state and federal governments, as well as violent conflicts over the spread of slavery into new states. Abraham Lincoln, candidate of the largely antislavery Republican Party, was elected president in 1860. Before he took office, seven slave states declared their secession—which the federal government maintained was illegal—and formed the Confederate States of America. With the Confederate attack upon Fort Sumter, the American Civil War began and four more slave states joined the Confederacy. Lincoln's Emancipation Proclamation declared slaves in the Confederacy to be free. Following the Union victory in 1865, three amendments to the U.S. Constitution ensured freedom for the nearly four million African Americans who had been slaves, made them citizens, and gave them voting rights. The war and its resolution led to a substantial increase in federal power.
After the war, the assassination of Lincoln radicalized Republican Reconstruction policies aimed at reintegrating and rebuilding the Southern states while ensuring the rights of the newly freed slaves. The resolution of the disputed 1876 presidential election by the Compromise of 1877 ended Reconstruction; Jim Crow laws soon disenfranchised many African Americans. In the North, urbanization and an unprecedented influx of immigrants from Southern and Eastern Europe hastened the country's industrialization. The wave of immigration, lasting until 1929, provided labor and transformed American culture. National infrastructure development spurred economic growth. The 1867 Alaska purchase from Russia completed the country's mainland expansion. The Wounded Knee massacre in 1890 was the last major armed conflict of the Indian Wars. In 1893, the indigenous monarchy of the Pacific Kingdom of Hawaii was overthrown in a coup led by American residents; the United States annexed the archipelago in 1898. Victory in the Spanish–American War the same year demonstrated that the United States was a world power and led to the annexation of Puerto Rico, Guam, and the Philippines. The Philippines gained independence a half-century later; Puerto Rico and Guam remain U.S. territories.
At the outbreak of World War I in 1914, the United States remained neutral. Most Americans sympathized with the British and French, although many opposed intervention. In 1917, the United States joined the Allies, helping to turn the tide against the Central Powers. After the war, the Senate did not ratify the Treaty of Versailles, which established the League of Nations. The country pursued a policy of unilateralism, verging on isolationism. In 1920, the women's rights movement won passage of a constitutional amendment granting women's suffrage. The prosperity of the Roaring Twenties ended with the Wall Street Crash of 1929 that triggered the Great Depression. After his election as president in 1932, Franklin D. Roosevelt responded with the New Deal, a range of policies increasing government intervention in the economy. The Dust Bowl of the mid-1930s impoverished many farming communities and spurred a new wave of western migration.
The United States, effectively neutral during World War II's early stages after Nazi Germany's invasion of Poland in September 1939, began supplying materiel to the Allies in March 1941 through the Lend-Lease program. On December 7, 1941, the Empire of Japan launched a surprise attack on Pearl Harbor, prompting the United States to join the Allies against the Axis powers. Participation in the war spurred capital investment and industrial capacity. Among the major combatants, the United States was the only nation to become richer—indeed, far richer—instead of poorer because of the war. Allied conferences at Bretton Woods and Yalta outlined a new system of international organizations that placed the United States and Soviet Union at the center of world affairs. As victory was won in Europe, a 1945 international conference held in San Francisco produced the United Nations Charter, which became active after the war. The United States, having developed the first nuclear weapons, used them on the Japanese cities of Hiroshima and Nagasaki in August. Japan surrendered on September 2, ending the war.
The United States and Soviet Union jockeyed for power after World War II during the Cold War, dominating the military affairs of Europe through NATO and the Warsaw Pact. The United States promoted liberal democracy and capitalism, while the Soviet Union promoted communism and a centrally planned economy. Both supported dictatorships and engaged in proxy wars. American troops fought Communist Chinese forces in the Korean War of 1950–53. The House Un-American Activities Committee pursued a series of investigations into suspected leftist subversion, while Senator Joseph McCarthy became the figurehead of anticommunist sentiment.
The 1961 Soviet launch of the first manned spaceflight prompted President John F. Kennedy's call for the United States to be first to land "a man on the moon," achieved in 1969. Kennedy also faced a tense nuclear showdown with Soviet forces in Cuba. Meanwhile, the United States experienced sustained economic expansion. A growing civil rights movement, symbolized and led by African Americans such as Rosa Parks, Martin Luther King, Jr., and James Bevel, used nonviolence to confront segregation and discrimination. Following Kennedy's assassination in 1963, the Civil Rights Act of 1964 and Voting Rights Act of 1965 were passed under President Lyndon B. Johnson. Johnson and his successor, Richard Nixon, expanded a proxy war in Southeast Asia into the unsuccessful Vietnam War. A widespread countercultural movement grew, fueled by opposition to the war, black nationalism, and the sexual revolution. Betty Friedan, Gloria Steinem, and others led a new wave of feminism that sought political, social, and economic equality for women.
As a result of the Watergate scandal, in 1974 Nixon became the first U.S. president to resign, to avoid being impeached on charges including obstruction of justice and abuse of power; he was succeeded by Vice President Gerald Ford. The Jimmy Carter administration of the late 1970s was marked by stagflation and the Iran hostage crisis. The election of Ronald Reagan as president in 1980 heralded a rightward shift in American politics, reflected in major changes in taxation and spending priorities. His second term in office brought both the Iran-Contra scandal and significant diplomatic progress with the Soviet Union. The subsequent Soviet collapse ended the Cold War.
Under President George H. W. Bush, the United States took a lead role in the UN–sanctioned Gulf War. The longest economic expansion in modern U.S. history—from March 1991 to March 2001—encompassed the Bill Clinton administration and the dot-com bubble. A civil lawsuit and sex scandal led to Clinton's impeachment in 1998, but he remained in office. The 2000 presidential election, one of the closest in American history, was resolved by a U.S. Supreme Court decision—George W. Bush, son of George H. W. Bush, became president.
On September 11, 2001, al-Qaeda terrorists struck the World Trade Center in New York City and The Pentagon near Washington, D.C., killing nearly three thousand people. In response, the Bush administration launched a "War on Terrorism". In late 2001, U.S. forces led an invasion of Afghanistan, removing the Taliban government and al-Qaeda training camps. Taliban insurgents continue to fight a guerrilla war. In 2002, the Bush administration began to press for regime change in Iraq on controversial grounds. Lacking the support of NATO or an explicit UN mandate for military intervention, Bush organized a Coalition of the Willing; coalition forces preemptively invaded Iraq in 2003, removing dictator Saddam Hussein. In 2005, Hurricane Katrina caused severe destruction along much of the Gulf Coast, devastating New Orleans. On November 4, 2008, amid a global economic recession, Barack Obama was elected president. He is the first African American to hold the office.
The United States is the world's oldest surviving federation. It is a constitutional republic and representative democracy, "in which majority rule is tempered by minority rights protected by law." The government is regulated by a system of checks and balances defined by the U.S. Constitution, which serves as the country's supreme legal document. In the American federalist system, citizens are usually subject to three levels of government, federal, state, and local; the local government's duties are commonly split between county and municipal governments. In almost all cases, executive and legislative officials are elected by a plurality vote of citizens by district. There is no proportional representation at the federal level, and it is very rare at lower levels.
The federal government is composed of three branches:
The House of Representatives has 435 voting members, each representing a congressional district for a two-year term. House seats are apportioned among the states by population every tenth year. As of the 2000 census, seven states have the minimum of one representative, while California, the most populous state, has fifty-three. The Senate has 100 members with each state having two senators, elected at-large to six-year terms; one third of Senate seats are up for election every other year. The president serves a four-year term and may be elected to the office no more than twice. The president is not elected by direct vote, but by an indirect electoral college system in which the determining votes are apportioned by state. The Supreme Court, led by the Chief Justice of the United States, has nine members, who serve for life.
The state governments are structured in roughly similar fashion; Nebraska uniquely has a unicameral legislature. The governor (chief executive) of each state is directly elected. Some state judges and cabinet officers are appointed by the governors of the respective states, while others are elected by popular vote.
All laws and governmental procedures are subject to judicial review, and any law ruled in violation of the Constitution is voided. The original text of the Constitution establishes the structure and responsibilities of the federal government and its relationship with the individual states. Article One protects the right to the "great writ" of habeas corpus, and Article Three guarantees the right to a jury trial in all criminal cases. Amendments to the Constitution require the approval of three-fourths of the states. The Constitution has been amended twenty-seven times; the first ten amendments, which make up the Bill of Rights, and the Fourteenth Amendment form the central basis of Americans' individual rights.
The United States has operated under a two-party system for most of its history. For elective offices at all levels, state-administered primary elections choose the major party nominees for subsequent general elections. Since the general election of 1856, the major parties have been the Democratic Party, founded in 1824, and the Republican Party, founded in 1854. Since the Civil War, only one third-party presidential candidate—former president Theodore Roosevelt, running as a Progressive in 1912—has won as much as 20% of the popular vote.
Within American political culture, the Republican Party is considered center-right or "conservative" and the Democratic Party is considered center-left or "liberal". The states of the Northeast and West Coast and some of the Great Lakes states, known as "blue states", are relatively liberal. The "red states" of the South and parts of the Great Plains and Rocky Mountains are relatively conservative.
The winner of the 2008 presidential election, Democrat Barack Obama, is the 44th U.S. president. All previous presidents were men of solely European descent. The 2008 elections also saw the Democratic Party strengthen its control of both the House and the Senate. In the 111th United States Congress, the Senate comprises 57 Democrats, two independents who caucus with the Democrats, and 41 Republicans; the House comprises 255 Democrats and 178 Republicans (two seats are vacant). There are 26 Democratic and 24 Republican state governors.
The United States is a federal union of fifty states. The original thirteen states were the successors of the thirteen colonies that rebelled against British rule. Early in the country's history, three new states were organized on territory separated from the claims of the existing states: Kentucky from Virginia; Tennessee from North Carolina; and Maine from Massachusetts. Most of the other states have been carved from territories obtained through war or purchase by the U.S. government. One set of exceptions comprises Vermont, Texas, and Hawaii: each was an independent republic before joining the union. During the American Civil War, West Virginia broke away from Virginia. The most recent state—Hawaii—achieved statehood on August 21, 1959. The states do not have the right to secede from the union.
The states compose the vast bulk of the U.S. land mass; the two other areas considered integral parts of the country are the District of Columbia, the federal district where the capital, Washington, is located; and Palmyra Atoll, an uninhabited but incorporated territory in the Pacific Ocean. The United States also possesses five major overseas territories: Puerto Rico and the United States Virgin Islands in the Caribbean; and American Samoa, Guam, and the Northern Mariana Islands in the Pacific. Those born in the territories (except for American Samoa) possess U.S. citizenship. American citizens residing in the territories have many of the same rights and responsibilities as citizens residing in the states; however, they are generally exempt from federal income tax, may not vote for president, and have only nonvoting representation in the U.S. Congress.
The United States exercises global economic, political, and military influence. It is a permanent member of the United Nations Security Council and New York City hosts the United Nations Headquarters. Almost all countries have embassies in Washington, D.C., and many have consulates around the country. Likewise, nearly all nations host American diplomatic missions. However, Cuba, Iran, North Korea, Bhutan, Sudan, and the Republic of China (Taiwan) do not have formal diplomatic relations with the United States.
The United States enjoys strong ties with the United Kingdom, Canada, Australia, New Zealand, Japan, South Korea, and Israel. It works closely with fellow NATO members on military and security issues and with its neighbors through the Organization of American States and free trade agreements such as the trilateral North American Free Trade Agreement with Canada and Mexico. In 2008, the United States spent a net $25.4 billion on official development assistance, the most in the world. As a share of gross national income (GNI), however, the U.S. contribution of 0.18% ranked last among twenty-two donor states. In contrast, private overseas giving by Americans is relatively generous.
The president holds the title of commander-in-chief of the nation's armed forces and appoints its leaders, the secretary of defense and the Joint Chiefs of Staff. The United States Department of Defense administers the armed forces, including the Army, Navy, Marine Corps, and Air Force. The Coast Guard is run by the Department of Homeland Security in peacetime and the Department of the Navy in time of war. In 2008, the armed forces had 1.4 million personnel on active duty. The Reserves and National Guard brought the total number of troops to 2.3 million. The Department of Defense also employed about 700,000 civilians, not including contractors.
Military service is voluntary, though conscription may occur in wartime through the Selective Service System. American forces can be rapidly deployed by the Air Force's large fleet of transport aircraft, the Navy's eleven active aircraft carriers, and Marine Expeditionary Units at sea with the Navy's Atlantic and Pacific fleets. Outside of the United States, the military operates 865 bases and facilities, with personnel deployed to more than 150 countries. The extent of this global military presence has prompted some scholars to describe the United States as maintaining an "empire of bases."
Total U.S. military spending in 2008, more than $600 billion, was over 41% of global military spending and greater than the next fourteen largest national military expenditures combined. The per capita spending of $1,967 was about nine times the world average; at 4% of GDP, the rate was the second-highest among the top fifteen military spenders, after Saudi Arabia. The proposed base Department of Defense budget for 2010, $533.8 billion, is a 4% increase over 2009 and 80% higher than in 2001; an additional $130 billion is proposed for the military campaigns in Iraq and Afghanistan. In September 2009 there were about 62,000 U.S. troops deployed to Afghanistan, and as of February 2010 there were 98,000 U.S. troops deployed to Iraq. As of October 9, 2009, the United States had suffered 4,349 military fatalities during the Iraq War, and 869 during the War in Afghanistan.
|Unemployment||9.7% (January 2010)|||
|GDP growth||5.9% (4Q 2009) [-2.4%(2009)]|||
|CPI inflation||2.6% (January 2009 – January 2010)|||
|Public debt||$12.303 trillion (January 5, 2010)|||
|Household net worth||$54.2 trillion (4Q 2009) [▲1.3% 2009]|||
The United States has a capitalist mixed economy, which is fueled by abundant natural resources, a well-developed infrastructure, and high productivity. According to the International Monetary Fund, the U.S. GDP of $14.4 trillion constitutes 24% of the gross world product at market exchange rates and almost 21% of the gross world product at purchasing power parity (PPP). The largest national GDP in the world, it was about 5% less than the combined GDP of the European Union at PPP in 2008. The country ranks seventeenth in the world in nominal GDP per capita and sixth in GDP per capita at PPP.
The United States is the largest importer of goods and third largest exporter, though exports per capita are relatively low. In 2008, the total U.S. trade deficit was $696 billion. Canada, China, Mexico, Japan, and Germany are its top trading partners. In 2007, vehicles constituted both the leading import and leading export commodity. China is the largest foreign holder of U.S. public debt. After an expansion that lasted just over six years, the U.S. economy has been in recession since December 2007. The United States ranks second in the Global Competitiveness Report.
In 2009, the private sector is estimated to constitute 55.3% of the economy, with federal government activity accounting for 24.1% and state and local government activity (including federal transfers) the remaining 20.6%. The economy is postindustrial, with the service sector contributing 67.8% of GDP, though the United States remains an industrial power. The leading business field by gross business receipts is wholesale and retail trade; by net income it is manufacturing. Chemical products are the leading manufacturing field. The United States is the third largest producer of oil in the world, as well as its largest importer. It is the world's number one producer of electrical and nuclear energy, as well as liquid natural gas, sulfur, phosphates, and salt. While agriculture accounts for just under 1% of GDP, the United States is the world's top producer of corn and soybeans. The New York Stock Exchange is the world's largest by dollar volume. Coca-Cola and McDonald's are the two most recognized brands in the world.
In the third quarter of 2009, the American labor force comprised 154.4 million people. Of those employed, 81% had jobs in the service sector. With 22.4 million people, government is the leading field of employment. About 12% of workers are unionized, compared to 30% in Western Europe. The World Bank ranks the United States first in the ease of hiring and firing workers. Between 1973 and 2003, a year's work for the average American grew by 199 hours. Partly as a result, the United States maintains the highest labor productivity in the world. In 2008, it also led the world in productivity per hour, overtaking Norway, France, Belgium and Luxembourg, which had surpassed the United States for most of the preceding decade. Compared to Europe, U.S. property and corporate income tax rates are generally higher, while labor and, particularly, consumption tax rates are lower.
According to the United States Census Bureau, the pretax median household income in 2007 was $50,233. The median ranged from $68,080 in Maryland to $36,338 in Mississippi. Using purchasing power parity exchange rates, the overall median is similar to the most affluent cluster of developed nations. After declining sharply during the middle of the 20th century, poverty rates have plateaued since the early 1970s, with 11–15% of Americans below the poverty line every year, and 58.5% spending at least one year in poverty between the ages of 25 and 75. In 2007, 37.3 million Americans lived in poverty.
The U.S. welfare state is now among the most austere in the developed world, reducing both relative poverty and absolute poverty by considerably less than the mean for rich nations. While the American welfare state does well in reducing poverty among the elderly, the young receive relatively little assistance. A 2007 UNICEF study of children's well-being in twenty-one industrialized nations ranked the United States next to last.
Despite strong increases in productivity, low unemployment, and low inflation, income gains since 1980 have been slower than in previous decades, less widely shared, and accompanied by increased economic insecurity. Between 1947 and 1979, real median income rose by over 80% for all classes, with the incomes of poor Americans rising faster than those of the rich. Median household income has increased for all classes since 1980, largely owing to more dual-earner households, the closing of the gender gap, and longer work hours, but growth has been slower and strongly tilted toward the very top (see graph). Consequently, the share of income of the top 1%—21.8% of total reported income in 2005—has more than doubled since 1980, leaving the United States with the greatest income inequality among developed nations. The top 1% pays 27.6% of all federal taxes; the top 10% pays 54.7%. Wealth, like income, is highly concentrated: The richest 10% of the adult population possesses 69.8% of the country's household wealth, the second-highest share among developed nations. The top 1% possesses 33.4% of net wealth.
The United States has been a leader in scientific research and technological innovation since the late 19th century. In 1876, Alexander Graham Bell was awarded the first U.S. patent for the telephone. Thomas Edison's laboratory developed the phonograph, the first long-lasting light bulb, and the first viable movie camera. Nikola Tesla pioneered alternating current, the AC motor, and radio. In the early 20th century, the automobile companies of Ransom E. Olds and Henry Ford promoted the assembly line. The Wright brothers, in 1903, made the first sustained and controlled heavier-than-air powered flight.
The rise of Nazism in the 1930s led many European scientists, including Albert Einstein and Enrico Fermi, to immigrate to the United States. During World War II, the Manhattan Project developed nuclear weapons, ushering in the Atomic Age. The Space Race produced rapid advances in rocketry, materials science, and computers. The United States largely developed the ARPANET and its successor, the Internet. Today, the bulk of research and development funding, 64%, comes from the private sector. The United States leads the world in scientific research papers and impact factor. Americans possess high levels of technological consumer goods, and almost half of U.S. households have broadband Internet access. The country is the primary developer and grower of genetically modified food; more than half of the world's land planted with biotech crops is in the United States.
Everyday personal transportation in America is dominated by the automobile. As of 2003, there were 759 automobiles per 1,000 Americans, compared to 472 per 1,000 inhabitants of the European Union the following year. About 40% of personal vehicles are vans, SUVs, or light trucks. The average American adult (accounting for all drivers and nondrivers) spends 55 minutes driving every day, traveling 29 miles (47 km).
The civil airline industry is entirely privately owned, while most major airports are publicly owned. The four largest airlines in the world by passengers carried are American; Southwest Airlines is number one. Of the world's thirty busiest passenger airports, sixteen are in the United States. It is also home to the busiest airport in the world, Hartsfield-Jackson Atlanta International Airport. While transport of goods by rail is extensive, relatively few people use rail to travel, within or between cities. Mass transit accounts for 9% of total U.S. work trips, compared to 38.8% in Europe. Bicycle usage is minimal, well below European levels.
The United States energy market is 29,000 terawatt hours per year. Energy consumption per capita is 7.8 tons of oil equivalent per year, compared to Germany's 4.2 tons and Canada's 8.3 tons. In 2005, 40% of this energy came from petroleum, 23% from coal, and 22% from natural gas. The remainder was supplied by nuclear power and renewable energy sources. The United States is the world's largest consumer of petroleum. For decades, nuclear power has played a limited role relative to many other developed countries, in part due to public perception in the wake of the 1979 Three Mile Island accident. In 2007, several applications for new nuclear plants were filed.
The United States population is projected by the U.S. Census Bureau to be 308,884,000, including an estimated 11.2 million illegal immigrants. The United States is the third most populous nation in the world, after China and India. Its population growth rate is 0.98%, compared to the European Union's 0.11%. The birth rate of 13.82 per 1,000, 30% below the world average, is higher than any European country's except Albania and Ireland. In fiscal year 2008, 1.1 million immigrants were granted legal residence. Mexico has been the leading source of new residents for over two decades; since 1998, China, India, and the Philippines have been in the top four sending countries every year. The United States is the only industrialized nation in which large population increases are projected.
The United States has a very diverse population—thirty-one ancestry groups have more than a million members. White Americans are the largest racial group; German Americans, Irish Americans, and English Americans constitute three of the country's four largest ancestry groups. African Americans are the nation's largest racial minority and third largest ancestry group. Asian Americans are the country's second largest racial minority; the two largest Asian American ethnic groups are Chinese American and Filipino American. In 2008, the U.S. population included an estimated 4.9 million people with some American Indian or Alaskan native ancestry (3.1 million exclusively of such ancestry) and 1.1 million with some native Hawaiian or Pacific island ancestry (0.6 million exclusively).
|Native American and Alaska Native||1.0%|
|Native Hawaiian and Pacific Islander||0.2%|
|Hispanic (of any race)||15.4%|
The population growth of Hispanic and Latino Americans (the terms are officially interchangeable) is a major demographic trend. The 46.9 million Americans of Hispanic descent are identified as sharing a distinct "ethnicity" by the Census Bureau; 64% of Hispanic Americans are of Mexican descent. Between 2000 and 2008, the country's Hispanic population increased 32% while the non-Hispanic population rose just 4.3%. Much of this growth is from immigration; as of 2007, 12.6% of the U.S. population was foreign-born, with 54% of that figure born in Latin America. Fertility is also a factor; the average Hispanic woman gives birth to three children in her lifetime. The comparable fertility rate is 2.2 for non-Hispanic black women and 1.8 for non-Hispanic white women (below the replacement rate of 2.1). Minorities (as defined by the Census Bureau, all those beside non-Hispanic, non-multiracial whites) constitute 34% of the population; they are projected to be the majority by 2042.
About 82% of Americans live in urban areas (as defined by the Census Bureau, such areas include the suburbs); about half of those reside in cities with populations over 50,000. In 2008, 273 incorporated places had populations over 100,000, nine cities had more than 1 million residents, and four global cities had over 2 million (New York City, Los Angeles, Chicago, and Houston). There are fifty-two metropolitan areas with populations greater than 1 million. Of the fifty fastest-growing metro areas, forty-seven are in the West or South. The metro areas of Dallas, Houston, Atlanta, and Phoenix all grew by more than a million people between 2000 and 2008.
|Leading population centers|
|Rank||Core city||Metro area pop.||Metropolitan Statistical Area||Region||
New York City
|1||New York||19,006,798||New York-Northern New Jersey-Long Island, NY-NJ-PA MSA||Northeast|
|2||Los Angeles||12,872,808||Los Angeles-Long Beach-Santa Ana, CA MSA||West|
|3||Chicago||9,569,624||Chicago-Naperville-Joliet, IL-IN-WI MSA||Midwest|
|4||Dallas||6,300,006||Dallas-Fort Worth-Arlington, TX MSA||South|
|5||Philadelphia||5,838,471||Philadelphia-Camden-Wilmington, PA-NJ-DE-MD MSA||Northeast|
|6||Houston||5,728,143||Houston-Sugar Land-Baytown, TX MSA||South|
|7||Miami||5,414,772||Miami-Fort Lauderdale-Pompano Beach, FL MSA||South|
|8||Atlanta||5,376,285||Atlanta-Sandy Springs-Marietta, GA MSA||South|
|9||Washington, D.C.||5,358,130||Washington-Arlington-Alexandria, DC-VA-MD-WV MSA||South|
|10||Boston||4,522,858||Boston-Cambridge-Quincy, MA-NH MSA||Northeast|
|based on 2008 U.S. Census Bureau estimates|
|English (only)||224.2 million|
|Spanish, incl. Creole||34.0 million|
|French, incl. Creole||2.0 million|
English is the de facto national language. Although there is no official language at the federal level, some laws—such as U.S. naturalization requirements—standardize English. In 2006, about 224 million, or 80% of the population aged five years and older, spoke only English at home. Spanish, spoken by 12% of the population at home, is the second most common language and the most widely taught second language. Some Americans advocate making English the country's official language, as it is in at least twenty-eight states. Both Hawaiian and English are official languages in Hawaii by state law. While neither has an official language, New Mexico has laws providing for the use of both English and Spanish, as Louisiana does for English and French. Other states, such as California, mandate the publication of Spanish versions of certain government documents including court forms. Several insular territories grant official recognition to their native languages, along with English: Samoan and Chamorro are recognized by American Samoa and Guam, respectively; Carolinian and Chamorro are recognized by the Northern Mariana Islands; Spanish is an official language of Puerto Rico.
The United States is officially a secular nation; the First Amendment of the U.S. Constitution guarantees the free exercise of religion and forbids the establishment of any religious governance. In a 2002 study, 59% of Americans said that religion played a "very important role in their lives," a far higher figure than that of any other wealthy nation. According to a 2007 survey, 78.4% of adults identified themselves as Christian, down from 86.4% in 1990. Protestant denominations accounted for 51.3%, while Roman Catholicism, at 23.9%, was the largest individual denomination. The study categorizes white evangelicals, 26.3% of the population, as the country's largest religious cohort; another study estimates evangelicals of all races at 30–35%. The total reporting non-Christian religions in 2007 was 4.7%, up from 3.3% in 1990. The leading non-Christian faiths were Judaism (1.7%), Buddhism (0.7%), Islam (0.6%), Hinduism (0.4%), and Unitarian Universalism (0.3%). From 8.2% in 1990, 16.1% in 2007 described themselves as agnostic, atheist, or simply having no religion.
American public education is operated by state and local governments, regulated by the United States Department of Education through restrictions on federal grants. Children are required in most states to attend school from the age of six or seven (generally, kindergarten or first grade) until they turn eighteen (generally bringing them through twelfth grade, the end of high school); some states allow students to leave school at sixteen or seventeen. About 12% of children are enrolled in parochial or nonsectarian private schools. Just over 2% of children are homeschooled. The United States has many competitive private and public institutions of higher education, as well as local community colleges with open admission policies. Of Americans twenty-five and older, 84.6% graduated from high school, 52.6% attended some college, 27.2% earned a bachelor's degree, and 9.6% earned graduate degrees. The basic literacy rate is approximately 99%. The United Nations assigns the United States an Education Index of 0.97, tying it for 12th in the world.
The United States life expectancy of 77.8 years at birth is a year shorter than the overall figure in Western Europe, and three to four years lower than that of Norway, Switzerland, and Canada. Over the past two decades, the country's rank in life expectancy has dropped from 11th to 42nd in the world. The infant mortality rate of 6.37 per thousand likewise places the United States 42nd out of 221 countries, behind all of Western Europe. U.S. cancer survival rates are the highest in the world. Approximately one-third of the adult population is obese and an additional third is overweight; the obesity rate, the highest in the industrialized world, has more than doubled in the last quarter-century. Obesity-related type 2 diabetes is considered epidemic by health care professionals. The U.S. adolescent pregnancy rate, 79.8 per 1,000 women, is nearly four times that of France and five times that of Germany. Abortion, legal on demand, is highly controversial. Many states ban public funding of the procedure and restrict late-term abortions, require parental notification for minors, and mandate a waiting period. While the abortion rate is falling, the abortion ratio of 241 per 1,000 live births and abortion rate of 15 per 1,000 women aged 15–44 remain higher than those of most Western nations.
The U.S. health care system far outspends any other nation's, measured in both per capita spending and percentage of GDP. The World Health Organization ranked the U.S. health care system in 2000 as first in responsiveness, but 37th in overall performance. The United States is a leader in medical innovation. In 2004, the nonindustrial sector spent three times as much as Europe per capita on biomedical research.
Unlike in all other developed countries, health care coverage in the United States is not universal. In 2004, private insurance paid for 36% of personal health expenditures, private out-of-pocket payments covered 15%, and federal, state, and local governments paid for 44%. In 2005, 46.6 million Americans, 15.9% of the population, were uninsured, 5.4 million more than in 2001. The main cause of this rise is the drop in the number of Americans with employer-sponsored health insurance. The subject of uninsured and underinsured Americans is a major political issue. A 2009 study estimated that lack of insurance is associated with nearly 45,000 deaths a year. In 2006, Massachusetts became the first state to mandate universal health insurance.
Law enforcement in the United States is primarily the responsibility of local police and sheriff's departments, with state police providing broader services. Federal agencies such as the Federal Bureau of Investigation (FBI) and the U.S. Marshals Service have specialized duties. At the federal level and in almost every state, jurisprudence operates on a common law system. State courts conduct most criminal trials; federal courts handle certain designated crimes as well as certain appeals from the state systems.
Among developed nations, the United States has above-average levels of violent crime and particularly high levels of gun violence and homicide. In 2007, there were 5.6 murders per 100,000 persons, three times the rate in neighboring Canada. The U.S. homicide rate, which decreased by 42% between 1991 and 1999, has been roughly steady since. Gun ownership rights are the subject of contentious political debate.
The United States has the highest documented incarceration rate and total prison population in the world. At the start of 2008, more than 2.3 million people were incarcerated, more than one in every 100 adults. The current rate is about seven times the 1980 figure. African American males are jailed at about six times the rate of white males and three times the rate of Hispanic males. In 2006, the U.S. incarceration rate was over three times the figure in Poland, the Organisation for Economic Co-operation and Development (OECD) country with the next highest rate. The country's high rate of incarceration is largely due to sentencing and drug policies.
Though it has been abolished in most Western nations, capital punishment is sanctioned in the United States for certain federal and military crimes, and in thirty-six states. Since 1976, when the U.S. Supreme Court reinstated the death penalty after a four-year moratorium, there have been more than 1,000 executions. In 2006, the country had the sixth highest number of executions in the world, following China, Iran, Pakistan, Iraq, and Sudan. In 2007, New Jersey became the first state to legislatively abolish the death penalty since the 1976 Supreme Court decision, followed by New Mexico in 2009.
The United States is a multicultural nation, home to a wide variety of ethnic groups, traditions, and values. Aside from the now small Native American and Native Hawaiian populations, nearly all Americans or their ancestors immigrated within the past five centuries. The culture held in common by most Americans—mainstream American culture—is a Western culture largely derived from the traditions of European immigrants with influences from many other sources, such as traditions brought by slaves from Africa. More recent immigration from Asia and especially Latin America has added to a cultural mix that has been described as both a homogenizing melting pot and a heterogeneous salad bowl in which immigrants and their descendants retain distinctive cultural characteristics.
According to Geert Hofstede's cultural dimensions analysis, the United States has the highest individualism score of any country studied. While the mainstream culture holds that the United States is a classless society, scholars identify significant differences between the country's social classes, affecting socialization, language, and values. The American middle and professional class has initiated many contemporary social trends such as modern feminism, environmentalism, and multiculturalism. Americans' self-images, social viewpoints, and cultural expectations are associated with their occupations to an unusually close degree. While Americans tend greatly to value socioeconomic achievement, being ordinary or average is generally seen as a positive attribute. Though the American Dream, or the perception that Americans enjoy high social mobility, plays a key role in attracting immigrants, some analysts find that the United States has less social mobility than Western Europe and Canada.
Women now mostly work outside the home and receive a majority of bachelor's degrees. In 2007, 58% of Americans age 18 and over were married, 6% were widowed, 10% were divorced, and 25% had never been married. Same-sex marriage is contentious. Some states permit civil unions in lieu of marriage. Since 2003, several states have permitted gay marriage as the result of judicial or legislative action, while voters in more than a dozen states have barred the practice via referendum.
The world's first commercial motion picture exhibition was given in New York City in 1894, using Thomas Edison's Kinetoscope. The next year saw the first commercial screening of a projected film, also in New York, and the United States was in the forefront of sound film's development in the following decades. Since the early 20th century, the U.S. film industry has largely been based in and around Hollywood, California. Director D. W. Griffith was central to the development of film grammar and Orson Welles's Citizen Kane (1941) is frequently cited as the greatest film of all time. American screen actors like John Wayne and Marilyn Monroe have become iconic figures, while producer/entrepreneur Walt Disney was a leader in both animated film and movie merchandising. The major film studios of Hollywood have produced the most commercially successful movies in history, such as Star Wars (1977) and Titanic (1997), and the products of Hollywood today dominate the global film industry.
Americans are the heaviest television viewers in the world, and the average viewing time continues to rise, reaching five hours a day in 2006. The four major broadcast networks are all commercial entities. Americans listen to radio programming, also largely commercialized, on average just over two-and-a-half hours a day. Aside from web portals and web search engines, the most popular websites are Facebook, YouTube, MySpace, Wikipedia, Craigslist, and eBay.
The rhythmic and lyrical styles of African American music have deeply influenced American music at large, distinguishing it from European traditions. Elements from folk idioms such as the blues and what is now known as old-time music were adopted and transformed into popular genres with global audiences. Jazz was developed by innovators such as Louis Armstrong and Duke Ellington early in the 20th century. Country music developed in the 1920s, and rhythm and blues in the 1940s. Elvis Presley and Chuck Berry were among the mid-1950s pioneers of rock and roll. In the 1960s, Bob Dylan emerged from the folk revival to become one of America's most celebrated songwriters and James Brown led the development of funk. More recent American creations include hip hop and house music. American pop stars such as Presley, Michael Jackson, and Madonna have become global celebrities.
In the eighteenth and early nineteenth centuries, American art and literature took most of its cues from Europe. Writers such as Nathaniel Hawthorne, Edgar Allan Poe, and Henry David Thoreau established a distinctive American literary voice by the middle of the 19th century. Mark Twain and poet Walt Whitman were major figures in the century's second half; Emily Dickinson, virtually unknown during her lifetime, is now recognized as an essential American poet. A work seen as capturing fundamental aspects of the national experience and character—such as Herman Melville's Moby-Dick (1851), Twain's The Adventures of Huckleberry Finn (1885), and F. Scott Fitzgerald's The Great Gatsby (1925)—may be dubbed the "Great American Novel."
Eleven U.S. citizens have won the Nobel Prize in Literature, most recently Toni Morrison in 1993. Ernest Hemingway, the 1954 Nobel laureate, is often named as one of the most influential writers of the 20th century. Popular literary genres such as the Western and hardboiled crime fiction developed in the United States. The Beat Generation writers opened up new literary approaches, as have postmodernist authors such as John Barth, Thomas Pynchon, and Don DeLillo.
The transcendentalists, led by Thoreau and Ralph Waldo Emerson, established the first major American philosophical movement. After the Civil War, Charles Sanders Peirce and then William James and John Dewey were leaders in the development of pragmatism. In the 20th century, the work of W. V. O. Quine and Richard Rorty brought analytic philosophy to the fore of U.S. academics. John Rawls and Robert Nozick led a revival of political philosophy.
In the visual arts, the Hudson River School was a mid-19th-century movement in the tradition of European naturalism. The 1913 Armory Show in New York City, an exhibition of European modernist art, shocked the public and transformed the U.S. art scene. Georgia O'Keeffe, Marsden Hartley, and others experimented with new styles, displaying a highly individualistic sensibility. Major artistic movements such as the abstract expressionism of Jackson Pollock and Willem de Kooning and the pop art of Andy Warhol and Roy Lichtenstein developed largely in the United States. The tide of modernism and then postmodernism has brought fame to American architects such as Frank Lloyd Wright, Philip Johnson, and Frank Gehry.
One of the first major promoters of American theater was impresario P. T. Barnum, who began operating a lower Manhattan entertainment complex in 1841. The team of Harrigan and Hart produced a series of popular musical comedies in New York starting in the late 1870s. In the 20th century, the modern musical form emerged on Broadway; the songs of musical theater composers such as Irving Berlin, Cole Porter, and Stephen Sondheim have become pop standards. Playwright Eugene O'Neill won the Nobel literature prize in 1936; other acclaimed U.S. dramatists include multiple Pulitzer Prize winners Tennessee Williams, Edward Albee, and August Wilson.
Though largely overlooked at the time, Charles Ives's work of the 1910s established him as the first major U.S. composer in the classical tradition; other experimentalists such as Henry Cowell and John Cage created an American approach to classical composition. Aaron Copland and George Gershwin developed a unique synthesis of popular and classical music. Choreographers Isadora Duncan and Martha Graham helped create modern dance, while George Balanchine and Jerome Robbins were leaders in 20th century ballet. Americans have long been important in the modern artistic medium of photography, with major photographers including Alfred Stieglitz, Edward Steichen, and Ansel Adams. The newspaper comic strip and the comic book are both U.S. innovations. Superman, the quintessential comic book superhero, has become an American icon.
Mainstream American culinary arts are similar to those in other Western countries. Wheat is the primary cereal grain. Traditional American cuisine uses ingredients such as turkey, white-tailed deer venison, potatoes, sweet potatoes, corn, squash, and maple syrup, indigenous foods employed by Native Americans and early European settlers. Slow-cooked pork and beef barbecue, crab cakes, potato chips, and chocolate chip cookies are distinctively American styles. Soul food, developed by African slaves, is popular around the South and among many African Americans elsewhere. Syncretic cuisines such as Louisiana creole, Cajun, and Tex-Mex are regionally important.
Characteristic dishes such as apple pie, fried chicken, pizza, hamburgers, and hot dogs derive from the recipes of various immigrants. French fries, Mexican dishes such as burritos and tacos, and pasta dishes freely adapted from Italian sources are widely consumed. Americans generally prefer coffee to tea. Marketing by U.S. industries is largely responsible for making orange juice and milk ubiquitous breakfast beverages. During the 1980s and 1990s, Americans' caloric intake rose 24%; frequent dining at fast food outlets is associated with what health officials call the American "obesity epidemic." Highly sweetened soft drinks are widely popular; sugared beverages account for 9% of the average American's caloric intake.
Since the late 19th century, baseball has been regarded as the national sport; American football, basketball, and ice hockey are the country's three other leading professional team sports. College football and basketball attract large audiences. Football is now by several measures the most popular spectator sport. Boxing and horse racing were once the most watched individual sports, but they have been eclipsed by golf and auto racing, particularly NASCAR. Soccer is played widely at the youth and amateur levels. Tennis and many outdoor sports are popular as well.
While most major U.S. sports have evolved out of European practices, basketball, volleyball, skateboarding, snowboarding, and cheerleading are American inventions. Lacrosse and surfing arose from Native American and Native Hawaiian activities that predate Western contact. Eight Olympic Games have taken place in the United States. The United States has won 2,301 medals at the Summer Olympic Games, more than any other country, and 253 in the Winter Olympic Games, the second most.
This article is for quotes about the United States of America, also known as the USA and the U.S.
UNITED STATES, The, the short title usually given to the great federal republic which had its origin in the revolt of the British colonies in North America, when, in the Declaration of Independence, they described themselves as The Thirteen United States of America. Officially the name is The United States of America, but The United States (used as a singular and not a plural) has become accepted as the name of the country; and pre-eminent usage has now made its citizens Americans, in distinctiofi from the other inhabitants of North and South America.
The area of the United States, as here considered, exclusive of Alaska and outlying possessions, occupies a belt nearly twenty degrees of middle latitude in width, and crosses Boundaries sad Area, North America from the Atlantic to the Pacific. The southern boundary is naturally defined on the east by the Gulf of Mexico; its western extension crosses obliquely over the western highlands, along an irregular line determined by aggressive Americans of Anglo-Saxon stock against Americans of Spanish stock. The northern boundary, after an arbitrary beginning, finds a natural extension along the Great Lakes, and thence continues along the 49th parallel of north latitude to the Pacific (see Bulletin 171, U.S. Geological Survey). The area thus included is 3,026,789 sq. m.
|New Hampshire (N.H.)|
|New Jersey (N.J.)|
|New Mexico (N. Mex.)|
|New York (N.Y.)|
|North Carolina (N.C.)|
|North Dakota (N. Dak.)|
|Rhode Island (R.I.)|
|South Carolina (S.C.)|
|South Dakota (S. Dak.)|
|West Virginia (W. Va.)|
|together with the
District of Columbia (D.C.)
|Table of contents|
A.-Beginnings of Self-government, 1578-1690.
The Atlantic coast of the United States is, with minor exceptions, low; the Pacific coast is, with as few exceptions, hilly or mountainous. The Atlantic coast owes its oblique N.E.S.W. trend to crustal deformations which in very early geological time gave a beginning to what later came to be the Appalachian mountain system; but this system had Its climax of deformation so long ago (probably in Permian time) that it has since then been very generally reduced to moderate or low relief, and owes its present altitude either to renewed elevations along the earlier lines or to the survival of the most resistant rocks as residual mountains. The oblique trend of the coast would be even more pronounced but for a comparatively modern crustal movement, causing a depression in the northeast, with a resulting encroachment of the sea upon the land, and an elevation. in the south-west, with a resulting advance of the land upon the sea. The Pacific coast has been defined chiefly by relatively recent crustal deformations, and hence still preserves a greater relief than that of the Atlantic. The minor features of each coast will be mentioned in connection with the lani districts of which the coast-line is only the border.
The low Atlantic coast and the hilly or mountainous Pacific coast foreshadow the leading features in the distribution of mountains within the United States. The Appalachian system, originally forest-covered, on the eastern side of the continent, is relatively low and narrow; it is bordered on the south-east and south by an important coastal plain. The Cordilleran system on the western side of the continent is lofty, broad and complicated, with heavy forests near the north-west coast, but elsewhere with trees only on the higher ranges below the Alpine region, and with treeless or desert intermont valleys, plateaus and basins, very arid in the south-west. Between the two mountain systems extends a great central area of plains, stretching from the Gulf of Mexico northward, far beyond the national boundary, to the Arctic Ocean. The~ rivers that drain the Atlantic slope of the Appalachians are comparatively short; those that drain the Pacific slope include only two, the Columbia and the Colorado, which rise far inland, near the easternmost members of the Cordilleran system, and flow through plateaus and intermont basins to the ocean. The central plains are divided by a hardly perceptible height of land into a Canadian and a United States portion; from the latter the great Mississippi system discharges southward to the Gulf of Mexico. The upper Mississippi and some of the Ohio basin is the prairie region, with trees originally only along the watercourses; the uplands towards the Appalachians were included in the great eastern forested area; the western part of the plains has so dry a climate that its herbage is scanty, and in the south it is barren. The lacustrine system of the St Lawrence flows eastward from a relatively narrow drainage area.
The aboriginal occupants of the greater part of North America were comparatively few in number, and except in Mexico were not advanced beyond the savage state, The geological processes that placed a much narrower ocean between North America and western Europe than between North America and eastern Asia secured to the New World the good fortune of being colonized by the leading peoples of the occidental Old World, instead of by the less developed races of the Orient. The transoceanic invasion progressed slowly through the 17th and ~8th centuries, delayed by the head winds of a rough ocean which was crossed only in slow sailing vessels, and by the rough backwoods of the Appalachians, which retarded the penetration of wagon roads and canals into the interior. The invasion was wonderfully accelerated through the I9th century, when the vast area of the treeless prairies beyond the Appalachians was offered to the settler, and when steam transportation on sea and land replaced sailing vessels and wagons. The frontier was then swiftly carried across the eastern half of the central plains, but found a second delay in its advance occasioned by the dry climate of the western plains. It was chiefly the mineral wealth of the Cordilleran region, first developed on the far Pacific slope, and later in many parts of the inner mountain ranges, that urged pioneers across the dry plains into the apparently inhospitable mountain region; there the adventurous new-corners rapidly worked out one mining district after another, exhausting and abandoning the smaller camps to early decay and rushing in feverish excitement to new-found river fields, but establishing important centres of varied industries in the more important mining districts. It was not until the settlers learned to adapt themselves to the methods of wide-range cattle raising and of farming by irrigation that the greater value of the far western interior was recognized as a permanent home for an agricultural population.
The purchase of Louisiana a great area west of the Mississippi river from the French in 1803 has sometimes been said to be the cause of the westward expansion of the United States, but the Louisiana purchase has been better interpreted as the occasion for the expansion rather than its cause; for, as Lewis Evans of Philadelphia long ago recognized (1749), whoever gained possession of the Ohio Valleythe chiet eastern part of the central plainswould inevitably become the masters of the continent.
The area of the United States may be roughly divided into the Appalachian belt, the Cordilleras and the central plains, as already indicated. These large divisions need physiographic subdivision, which will now be made, following the guide of structure, process and stage; that is, each subdivision or province will be defined as part of the earths crust in which some similarity of geological structure prevails, and upon which some process or processes of surface sculpture have worked long enough to reach a certain stage in the cycle of physiographic development.
The physiographic description of the Appalachian mountain system offers an especially good opportunity for the application of the genetic method based on structure, process and stage. This mountain system consists essentially of two belts: one on the south-east, chiefly of ancient and greatly deformed crystalline rocks, the other on the north-west, a heavy series of folded Palaeozoic strata; and with these it will be convenient to associate a third belt, farther north-west, consisting of the same Palaeozoic strata lying essentially horizontal and constituting the Appalachian plateau. The crystalline belt represents, at least in part, the ancient highlands from whose ruins the sandstones, shales and limestones of the stratified series were formed, partly as ~narine, partly as fluviatile deposits. The deformation of the Appalachianswas accomplished in two chief periods of compressive deformation, one in early Palaeozoic, the other about the close of Palaeozoic time, and both undoubtedly of long duration; the second one extended its effects farther northwest than the first. These were followed by a period of minor tilting and faulting in early Mesozoic, by a moderate upwarping in Tertiary, and by a moderate uplift in post-Tertiary time. The later small movements are of importance because they are related to the existing topography with which we are here concerned. Each of the disturbances altered the attitude of the mass with respect to the general base-level of the ocean surface; each movement therefore introduced a new cycle of erosion, which was interrupted by a later movement and the beginning of a later cycle.
Thus interpreted, the Appalachian forms of to-day may be ascribed to three cycles of erosion: a nearly complete Mesozoic cycle, in which most of the previously folded and faulted mountain masses were reduced in Cretaceous time to a peneplain or lowland of small relief, surmounted, however, in the north-east and in the south-west by monadnocks of the most resistant rocks, standing singly or in groups; an incomplete Tertiary cycle, initiated by the moderate Tertiary upwarping of the Mesozoic peneplain, and of sufficient length to develop mature valleys in the more resistant rocks of the crystalline belt or in the horizontal strata of the plateau, and to develop late mature or old valleys in the weaker rocks of the stratified belt, where the harder strata were left standing up in ridges; and a brief post-Tertiary cycle, initiated by an uplift of moderate amount and in progress long enough only to erode narrow and relatively immature valleys. Glacial action complicated the work of the latest cycle in the northern part of the system. In view of all this it is possible to refer nearly every element of Appalachian form to its appropriate cycle and stage of development. The more resistant rocks, even though dissected by Tertiary erosion, retain in their summit tiplands an indication of the widespread peneplain of Cretaceous tinie, now standing at the altitude given to it by the Tertiary upwarping and post-Tertiary uplift; and the most resistant rocks surmount the Cretaceous peneplain as unconsumed monadnocks of the Mesozoic cycle. On the other hand, the weaker rocks are more or less completely reduced to lowlands by Tertiary erosion, and are now trenched by the narrow and shallow valleys of the short post-Tertiary cycle. Evi-Jently, therefore, the Appalachians as we now see them are not the still surviving remnants of the mountains of late Palaeozoic deformation; they owe their present height chiefly to the Tertiary upwaroing and uoliftinr. and their form to the normal urocesses of sculpture which, having become nearly quiescent at the close,of the Mesozoic cycle, became active again in Tertiary and later times.
The belts of structure and the cycles of erosion thus briefly described are recognizable with more or less continuity from the Gulf of St Lawrence i 500 m. south-westward to Alabama, where the deformed mountain structures pass out of sight under nearly horizontal strata of the Gulf coastal plain. But the dimensions of the several belts and the strength of the relief developed by their later erosion varies greatly along the system. In a north-eastern section, practically all of New England is occupied by the older crystalline belt; the corresponding northern part of the stratified belt in the St Lawrence and Champlain-Hudson valleys on the inland side of New England is comparatively free from the ridge-making rocks which abound farther south; and here the plateau member is wanting, being replaced, as it were, by the Adirondacks, an outlier of the Laurentian highlands of Canada which immediately succeeds the deformed stratified belt west of Lake Champlain. In a middle section of the system, from the Hudson river in southern New York to the James river in southern Virginia, the crystalline belt is narrowed, as if by the depression of its south-eastern part beneath the Atlantic Ocean or beneath the strata of the Atlantic coastal plain which now represents the ocean; but the stratified belt is here broadly developed in a remarkable series of ridges and valleys determined by the action of erosion on the many alternations of strong and weak folded strata; and the plateau assumes full strength southward from the monochinal Mohawk valley which separates it from the Adirondacks. The linear ridges of this mIddle section are often called the Alleghany Mountains. In a south-western section the crystalline belt again assumes importance in breadth and height, and the plateau member maintains the strength that it had in the middle section, but the intermediate stratified belt again has fewer ridges, -because of the infrequence here of ridge-making strata as compared to their frequency in the middle section.
|The Middle Appala- chians|
The middle section of the Appalachians, rather arbitrarily limited by the Hudson and the James rivers, may be described first because it contains the best representation of the three longitudinal belts of which the mountain system as a whole is The Middle composed. The mountain-making compression of the ,4pialaheavy series of Palaeozoic strata has here produced a chians. marvellous series of rock folds with gently undulating axes, trending north-east and south-west through a belt 70 or 80 m. wide; no less wonderful is the form that has been produced by the processes of sculpture. The peculiar configuration of thr~ ridges may be apprehended as follows: The pattern of the folded ~trata on the low-lying Cretaceous peneplain must have resembled the pattern of the curved grain of wood on a planed board. When the peneplain was uplifted the weaker strata were worn down almost to a lowland of a second generation, while the resistant sandstones, of which there a1~- three chief members, retained a great part of their new-gained altitude in the form of long, narrow, even-crested ridges, well deserving of the name of Endless Motintains given them by the Indians, but here and there bending sharply in peculiar zigzags which give this Alleghany section of the mountains an unusual individuality. The postTertiary uplift, giving the present altitude of 1000 or 1500 ft. in Pennsylvania, and of 2500 or 3500 ft. in Virginia, has not significantly altered the forms thus produced; it has only incited the rivers t0 intrench themselves 100 or more feet beneath the lowlands of tertiary erosion. The watercourses to-day are, as a rule, longitudinal, following the strike of the weaker strata in paths that they appear to have gained by spontaneous adjustment during the long Mesozoic cycle; but now and again they cross from one longitudinal valley to another by a transverse course, and there they have cut down sharp notches or water-gaps in the hard strata that elsewhere stand up in the long even-crested ridges.
The transition from the strongly folded structure of the Alleghany ridges and valleys to the nearly horizontal structure of the Appala; chian plateau is promptly made; and with the change of structure comes an appropriate change of form. The horizontal strata of the plateau present equal ease or difficulty of erosion in any direction; the streams and the submature valleys of the plateau therefore ramify in every direction, thus presenting a pattern that has been called insequent, because it follows no apparent control. Further mention of the plateau is made in a later section.
The crystalline belt of the middle Appalachians, 60 or 80 m- wide, is to-day of moderate height because the Tertiary upwarping was there of moderate amotint. The height is greatest along the inner or north-western border of the belt, and here a sub-mountainous topography has been produced by normal dissection, chiefly in the Tertiary cycle; the valleys being narrow because the rocks are resistant. The relief is strong enough to make occupation difficult; the slopes are forested; the uplands are cleared and well occupied b farms and villages, but many of the valleys are wooded glens. Wit continued decrease of altitude south-eastward, the crystalline belt dips under the coastal plain, near a line marked by the Delaware river from Trenton to Philadelphia in Pennsylvania, and thence south-south-westward through Maryland and Virginia past the cities of Baltimore, Washington and Richmond.
The Pennsylvania portionof the crystalline belt is narrow, as has been said, because of encroachment upon it by the inward overlap of the coastal olain: it ~s low because of small Tertiary unlift: but.
still more, it is discontinuous, because of the inclusion of certain belts of weak non-crystalline rock; here the rolling uplands are worn down to lowland belts, the longest of which reaches from the southern corner of New York, across New Jersey, Pennsylvania and Maryland, into central Virginia.
The middle section of the Appalachians is further distinguished from the north-eastern and south-western sections by the arrangeDrain age. ment of its drainage: its chief rivers rise in the plateau belt and flow across the ridges and valleys of the stratified belt and through the uplands of the crystalline belt to the sea. The rivers which most perfectly exemplify this habit are the Delaware, Susquehanna and Potomac; the Hudson, the north-eastern boundary of the middle section, is peculiar in having headwaters in the Adirondacks as well as in the Catskills (northern part of the plateau); the James, forming the south-western boundary of the section, rises in the inner valleys of the stratified belt, instead of in the plateau. The generally transverse course of these rivers has given rise to the suggestion that they are of antecedent origin; but there are many objections to this over-simple, Gordian explanation. The south-east course of the middle-section rivers is the result of many changes from the initial drainage; the Mesozoic and Tertiary upwarprngs were probably very influential in determining the present general courses.
For the most part the rivers follow open valleys along belts of weak strata; but they frequently pass through sharp-cut notches in the na1row ridges of the stratified beltthe Delaware water-gap is one of the deepest of these notches; and in the harder rocks of the crystalline belt they have eroded steep-walled gorges, of which the finest is that of the Hudson, because of the greater height and breadth of the crystalline highlands there than at points where the other rivers cross it. The rivers are shallow and more or less broken by rapids in the notches; rapids occur also near the outer border of the crystalline belt, as if the rivers there had been lately incited to downward erosion by an uplift of the region, and had not yet had time to regrade their courses. This is well shown in the falls of the Potomac a few miles above Washington; in the rapids 01 the lower Susquehanna; and in the falls of the Schuylkill, a branch which joins the Delaware at Philadelphia, where the water-power has long been used in extensive factories. Hence rivers in the Appalachians are not navigable; it is only farther down-stream, where the rivers have been converted into estuaries and bayssuch as Chesapeake and Delaware baysby a slight depression of the coastal plain belt, that they serve the purposes of navigation. But the Hudson is strikingly exceptional in this respect; it possesses a deep and navigable tide-water channel all through its gorge in the highlands, a feature which has usually been explained as the result of depression of the land, but may also be explained by glacial erosion without change of land-level; a feature which, in connection with the Mohawk Valley, has been absolutely determinative of the metropolitan rank reached by New York City at the Hudson mouth.
|The North- Eastern Ap- palachians.|
The community of characteristics that is suggested by the association of six north-eastern states under the name New England The North- is in large measure warranted by the inclusion of easternA all these states within the broadened crystalline belt palachians of the north-eastern Appalachians, which is here 150 m. wide. The uplands which prevail through the centre of this area at altitudes of about iooo ft. rise to 1500 o~ 2000 ft. in the north-west, before descent is made to the lowlands of the stratified belt (St Lawrence-Champlain-Hudson valleys, described later on as part of the Great Appalachian valley), and at the same time the rising uplands are diversified with monadnocks of increasing number and height and by mature valleys cut to greater and greater depths; thus the interior of New England is moderately mountainous. When the central uplands are followed south-east or south to the coast, their altitude and their relief over the valleys gradually decrease; and thus the surface gradually passes under the sea. The lower coastal parts, from their accessibility and their smaller relief, are more densely populated; the higher and more rugged interior is still largely forested and thinly settled; there are large tracts of unbroken forest in northern Maine, hardly 150 m. from the coast. In spite of these contrasts, no physiographic line can be drawn between the higher and more rugged interior and the lower coastal border; one merges into the other. New England is a unit, though a diversified unit.
The Appalachian trends (N.E.S.W.) that are so prominent in the stratified belt of the middle Appalachians, and are fairly well marked in the crystalline belt of New Jersey and Pennsylvania, are prevailingly absent in New England. They may be seen on the western border, in the Hoosac range along the boundary of Massachusetts and New York; in the linear series of the Green Mountain summits (Mt Mansfield. 4364 ft., Killington Peak, 4241 ft.) and their (west) piedmont ridges farther north in Vermont; and in the ridges of northern Maine: these are all in synipathy with Appalachian structure: so also are certain open valleys, as the Berkshire (limestone) Valley in western Massachusetts and the correspondin Rutland (limestone and marble) Valley in western Vermont; an more particularly the long Connecticut Valley from northern New Hampshire across Massachusetts to the sea at the southern border of Connecticut, the populous southern third of which is broadly &roded along a belt of red Triassic sandstones with trap ridges.
But in general the dissection of the New England upland is as irregular as is the distribution of the surmounting monadnocks. The type of this class of forms is Mt Monadnock in south-western New Hampshire, a fine example of an isolated residual mass rising from an upland some 1500 ft. in altitude and reaching a summit height of 3186 ft. A still larger example is seen in Mt Katahdin (5200 ft.) in north-central Maine, the greatest of several similar isolated mountains that-are scattered over the interior uplands without apparent system. The White Mountains of northern New Hampshire may be treated as a complex group of rnonadnocks, all of subdued forms, except for a few cliffs at the head of cirque-like valleys, with Mt Washington, the highest of, the dome-like or low pyramidal summits, reaching 6293 ft., and thirteen other summits over 5000 ft. The absence of range-like continuity is here emphasized by the occurrence of several low passes or notches leading directly through the group; the best-known being Crawfords Notch (1900 ft.).
In consequence of the general south-eastward slope of the highlands and uplands of New England, the divide between the Atlantic rivers and those which flow northward an~j westward D ~t into the lowland of the stratified belt in Canada and r New York is generally close to the boundary of these two physiographic districts. The chief rivers all flow south or south-east:
The drainage of New England is unlike that of the middle and south-western Appalachians in the occurrence of numerous lakes and falls. These irregular features are wanting south of the limits of Pleistocene glaciation; there the rivers have had time, in the latest cycle of erosion into which they have entered, to establish themselves in a continuous flow, and as a rule to wear down their courses to a smoothly graded slope. In New England also a wellestablished drainage undoubtedly prevailed in preglacial times; but partly in consequence of the irregular scouring of the rock floor, and even more because of the very irregular deposition of unstratified and stratified drift in the valleys, the drainage is now in great disorder. Many lakes of moderate size and irregular outline have been formed where drift deposits formed barriers across former river courses; the lake outlets are more or less displaced from former river paths. Smaller lakes were formed by the deposition of washed drift around the longest-lasting ice remnants; when the ice finally melted away, the hollows that it left came to be occupied by ponds and lakes. In Maine lakes of both classes are numerous; the largest is Moosehead Lake, about 35 m. long and of a very irregular shore line.
The features of a coast can be appreciated only when it is perceived that they result from the descent of the land surface beneath the sea and from the work of the sea ,upon the shore line thus determined; and it is for this reason that through- Coast, out this article the coastal features are described in connection with the districts of which they are the border. The maturely dissected and recently glaciated uplands of New England are now somewhat depressed with respect to sea-level, so that the sea enters the valleys, forming bays and estuaries, while the interfiuve uplands and hills stand forth in headlands and islands. Narragansett Bay, with the associated headlands and islands on the south coast, is one of the best examples. Where drift deposits border the sea, the shore line has been cut back or built forward in beaches of submature expression, often enclosing extensive tidal marshes; but the great part of the shore line is rocky, and there the change from initial pattern due to submergence is as yet small. Hence the coast as a whole is irregular, with numerous embayments, peninsulas and islands; and in Maine this irregularity reaches a disadvantageous climax.
|The South- Western Ap- palachians.|
As in the north-east, so in the south-west, the crystalline belt widens and gains in height; but while New England is an indivisible unit, the southern crystalline belt must be subdivided The Southinto a higher mountain belt on the north-west, 60 m. western A wide where broadest, and a lower piedmont belt on the p,,Jachjan~ south-east, 100 m. wide, from southern Virginia to South Carolina. This subdivision is already necessary in Maryland, where the mountain belt is represented by the Blue Ridge, which is rather a narrow upland belt than a ridge proper where the Potomac cuts across it; while the piedmont belt, relieved by occasional monadnocks stretches from the eastern base of the Blue Ridge to the coastal plain, into which it merges. Farther south, the mountain belt widens and attains its greatest development, a true highland district, in North Carolina, where it includes several strong mountain groups. Here Mt Mitchell risesto 6711 ft., the highest of the Appalachians, and about thirty other summits exceed 6000 ft., while the valleys are usually at altitudes of about 2000 ft. Although the relief is strong, the mountain forms are rounded rather than rugged; few of the summits deserve or receive the name of peaks; some are called domes, from their broadly rounded tons, others are known as balds, becatise the widespread forest cover is replaced over their heads by a grassy cap.
The height and massiveness of the mountains decrease to the south-west, where the piedmont belt sweeps westward around them in western Georgia and eastern Alabama Some of the residual mountains hereabouts are reduced to a mere skeleton or framework by the retrogressive penetration of widening valleys between wasting spurs; the very type of vanishing forms, Certain districts within the mountains, apparently consisting of less resistant crystalline rocks, have been reduced to basin-like peneplains in the same time that served only to grade the slopes and subdue the summits of the neighboring mountains of more resistant rocks; the best example of this kind is the Asheville peneplain in North Carolina, measuring about 40 by 20 m. across; but in consequence of later elevation, its general surface, now standing at an altitude of 2500 ft is mattirely dissected by the French Broad river and its many branches in valleys 300 ft. deep; the basin floor is no longer a plain, but a hilly district in the midst of the mountains; Asheville on its southern border is a noted health resort.
The rivers of the mountain belt, normally dividing and subdividing in apparently fnsequent fashion between the hills and spurs, generally follow open valleys; there are few waterfalls, the streams being as a rule fairly well graded, though their current is rapid and their channels are set with coarse waste. The valley floors always join at accordant levels, as is the habit among normally subdued mountains; they thus contrast with glaciated mountains such as the Alps and the Canadian Rockies, where the laterals habitually open as hanging valleys in the side slope of the main valleys. It is a peculiar feature of the drainage in North Carolina that the headwaters lie to the east of the highest mountains, and that the chief rivers flow north-westward through the mountains to the broad valley lowland of the stratified belt and then through the plateau, as the members of the Mississippi system. It is probable that these rivers follow in a general way courses of much more ancient origin than those of the Atlantic rivers in the middle Appalachians.
The piedmont belt may be described as a maturely dissected peneplain over much of its extent; it is indeed one of the best examples of that class of forms. Its uplands are of fairly accordant altitude, which gradually decreases from 500 to 1000 ft. near the mountain belt to half that height along the coastal plain border. The uplands are here and there surmounted by residual monadnocks in the form of low domes and knobs; these increase in height and number towards the mountain belt, and decrease towards the coastal plain: Stone Mountain, near Atlanta, Georgia, a dome of granite surmounting the schists of the uplands, is a striking example of this class of forms. The chief rivers flow south-eastward in rather irregular courses through valleys from 200 to 500 ft. deep; the small branches ramify indefinitely in typical insequent arrangement; the streams are nearly everywhere well graded; rapids are rare and lakes are unknown.
The bofindary between the mountains and the piedmont belt is called the Blue Ridge all along its length; and although the nan:e is fairly appropriate in northern Virginia, it is not deserved in the Carolinas, where the ridge is only an escarpment descending abruptly 1000 or 1500 ft~ from the valleys of the mountain belt to the rolling uplands of the piedmont belt; and as such it is a form of unusual occurrence. It is not defined by rock structure, but appears to result from the retrogressive erosion of the shorter Atlantic rivers, whereby the highlands, drained by much longer rivers, are undercut. The piedmont belt merges south-eastward into the coastal plain, the altitudes of the piedmont uplands and of the coastal plain hills being about the same along their line of junction. Many of the rivers, elsewhere well graded, have rapids as they pass from the harder rocks of the piedmont to the semi-consolidated strata of the coastal plain.
There is one feature of the Appalachians that has greater continuity than any other; this is the Great Valley. Itis determined The Great structurally by a belt of topographically weak limestones VaJie and shales (or slates) next inland from the crystalline ~ uplands; hence, whatever the direction of the rivers which drain the belt, it has been worn down by Tertiary erosion to a continuous lowland from the Gulf of St Lawrence to central Alabama. Through all this distance of 1500 in. the lowland is nowhere interrupted by a transverse ridge, although longittidinal ridges of moderate heiyht occasionally diversify its surface. In the middle section, as already stated, the Great Valley is somewhat open on the east, by reason of the small height and broad interruptions of the narrow crystalline belt; on the west it is limited by the complex series of Alleghany ridges and valleys; in the north-east section the valley is strongly enclosed on the east by the New England uplands, and on the west by the Adirondacks and Catskills (see below); in the south-west section the valley broadens from the North Carolina highlands on the south-east almost to the Cumberland plateau on the north-west, for here also the ridge-making formations weaken, although they do not entirely disappear.
A strikin,g contrast between New England and the rest of the Appalachians is found in the descent of the New England uplands Th At! ~ to an immediate frontage on the sea; while to the south of New York harbour the remainder of the Appala Plain chians are set back from the sea by the interposition of a coastal plain, one of the most characteristic examples of this class of forms anywhere to be found. As in all such cases, the plain consists of marine (with some estuarine and flu viatile) stratified deposits, more or less indurated, which were laid down when the land stood lower and the sea had its shore line farther inland than to-day. An uplift, increasing to the south, revealed part of the shallow sea bottom in the widening coastal plain, from its narrow beginning at New York harbour to its greatest breadth of 110 or 120 m. in Georgia: there it turns westward and is continued in the Gulf coastal plain, described farther on. The coastal plain, however, is the result, not of a single recent uplift, but of movements dating back to Tertiary time and continued with many oscillations to the present; nor is its surface smooth and unbroken, for erosion began upon the inner part of the plain long before the outer border was revealed. Indeed, the original interior border of the plain has been well stripped from its inland overlap; the higher-standing inner part of the plain is now maturely dissected, with a relief of 200 to 500 ft., by rivers extended seaward from the older land anti by their inntimerable branches, which are often of insequent arrangement; while the seaward border, latest uplifted, is prevailingly low and smooth, with a hardly perceptible seaward slope of but a few feet in a mile; and the shallow sea deepens very gradually for many nules off shore.
South Carolina and Georgia furnish the broadest and most typical section of this important physiographic province: here the more sandy and hilly interior parts are largely occupied by pine forests, which furnish much hard or yellow pine lumber, tar and turpentine. Farther seaward, where the relief is less and the soils are richer, the surface is cleared and cotton is an important crop.
A section of the coastal plain, from North Carolina to southern New Jersey, resembles the plain farther south in general form and quality of soils, but besides being narrower, it is further characterized by several embayments or arms of the sea, caused by a slight depression of the land after mature valleys had been eroded in the plain. The coastal lowland between the sea arms is so flat that, although distinctly above sea-level, vegetation hinders drainage and extensive swamps or pocossins occur. Dismal Swamp, on the border of North Carolina and Virginia, is the largest example.
The small triangular section of the coastal plain in New Jersey north of Delaware Bay deserves separate treatment because of the development there of a pectiliar topographic feature, which throws light on the occurrence of the islands off the New England coast, described in the next paragraph. The feature referred to results from the occurrence here of a weak basal formation of clay overlaid by more resistant sandy strata; the clay belt has been stripped for a score or more of miles from its original inland overlap, and worn down in a longitudinal inner lowland, while the sandy belt retains a significant altitude of 200 or 300 ft. overlooking the inner lowland in a well-defined slope dissected by many inland-flowing streams, and descending from its broad crest very gently seaward, thus giving ri~e to what has been called a belted coastal plain, in which the relief is arranged longitudinally and the upland member, with its very unsymmetrical slopes, has sometimes been called a cuesta. This is a ferm of relief frequently occurring elsewhere, as in the Niagara cuesta of the Great Lake district of the northern United States and in the Cotswold and Chiltern hills of England, typical examples of the cuesta class. The Delaware river, unlike its southern analogues, which pursue a relatively direct course to the sea, turns south-westward along the inner lowland for some 50 m.,
There is good reason for believing that at least along the southern border of New England a narrow coastal plain was for a time added to the continental border; and that, as in the New Jersey section the plain was here stripped from a significant breadth of inland overlap and worn down so as to form an inner lowland enclosed by a longitudinal upland or cuesta; and that when this stage was reached a submergence, of the kind which has produced the many embayments of the New England coast, drowned the outer part of thy plain and the inner lowland, leaving only the higher parts of the cuesta as islands. Thus Long Island (fronting Connecticut, but belonging to New York state), Block Island (part of the small state of Rhode Island), Marthas Vineyard and Nantucket (parts of Massachusetts) may be best explained. Heavy terminal moraines and outwashed fluviatile plains have been laid on the cuesta remnants, increasing their height as much as 100 ft. and burying their seaward slope with gravel and sand. Moreover, the sea has worked on the shore line thus originated, reducing the size of the more exposed islands farther east, and even consuming some islands which are now represented by the Nantucket shoals.
The same Paiaeozoic formations that are folded in the belt of the Alleghany ridges lie nearly horizontal in the plateau district next north-west. The exposed strata are in large part resistant sandstones. While they have suffered active e dissection by streams during the later cycles of erosion, ~ the hilltops have retained so considerable an altitude ~
that the district is known as a plateau; it might be better described as a dissected plateau, inasmuch as its uplands are not contiQuous but are nearly everywhere interrupted by ramifying insequent valleys. The unity and continuity of the district, expressed in the name Appalachian plateau, is seldom recognized in local usage. Its iiorth-eastern part in eastern New York is known as the Catskill Mountains; here it reaches truly mountainous heights in great dome-like masses of full-bodied form, with two summits rising a little over 4000 ft. The border of this part of the plateau descends eastward by a single strong escarpment to the Hudson valley, from which the mountains present a fine appearance, and northward by two escarpments (the second being called the Helderberg Mountains) to the Mohawk Valley, north of which rise the Adirondacks; but to the south west the dissected highland continues into Pennsylvania and Virginia, where it is commonly known as the Alleghany plateau. A curious feature appears in northern Pennsylvania: here the lateral pressure of the Palaeozoic mountain-making forces extended its effects through a belt about fifty miles wider than the folded belt of the Hudson Valley, thus compressing into great rock waves a part of the heavy stratified series which in New York lies horizontal and forms the Catskills; hence one sees, in passing south-west from the horizontal to the folded strata, a beautiful illustration of the manner in which land sculpture is controlled by land structure. Altitudes of 1200 ft. prevail in Pennsylvania and increase in Virginia; then the altitude falls to about 1000 ft. in Kentucky and Tennessee, where the name Cumberland plateau is used for the highest portion, and to still less in northern Alabama, where the plateau, like the mountain belt, disappears under the Gulf coastal plain. Through all this distance of 1000 m. the border of the plateau on the south-east is an abrupt escarpment, eroded where the folded structure of the mountain belt reveals a series of weaker strata; but in the north-west the plateau suffers only a gradual decrease of height and of relief, until the prairie plains are reached in central Ohio and southern Indiana and Illinois, about 150 m. inland from the escarpment. Two qualifications must, however, be added. In certain parts of the plateau there are narrow anticlinal uplifts, an outlying effect of mountain-making compression; here a ridge rises if the exposed strata are resistant, as in Chestnut ridge of western Pennsylvania; but here a valley is excavated if the exposed strata are weak, as in Sequatchie Valley, a long narrow trough which cuts off a strip of the plateau from its greater body in Tennessee. Again, in Kentucky and Tennessee, there is a double alternation of sandstone and limestone in the plateau-making strata; and as the skyline of the plateau bevels across these formations, there are west-facing escarpments, made ragged by mature dissection, as one passes from the topographically strong sandstone to the topographically weak limestone.
In the north-east (New York and Pennsylvania) the higher parts of the plateau are drained by the Delaware and Susquehanna rivers directly to the Atlantic; farther west and south-west, the plateau is drained to the Ohio rrver and its branches. The submature or mature dissection of the plateau by its branching insequent streams results in giving it an excess of sloping surface, usually too steep for farming, and hence left for tree growth.
The Superior Oldland.An outlying upland of the Laurentian highlands of Canada projects into the United States west and south of Lake Superior. Although composed chiefly of crystalline rocks, which are commonly associated with a rugged landscape, and although possessing a greatly deformed structure, which must at some ancient period have been associated with strong relief, the upland as a whole is gently rolling, and the inter-stream surfaces are prevailing plateau-like in their evenness, with altitudes of 1400 to 1600 ft. in their higher areas. In this province, therefore, we find a part of one of those ancient mountain regions, initiated by crustal deformation, but reduced by long continued erosion to a peneplain of modern relief, with occasional surmounting monadnocks of moderate height not completely consumed during the peneplanation of the rest of the surface. The erosion of the region must have been far advanced, perhaps practically completed, in very ancient times, for the even surface of the peneplain is overlapped by fossiliferous marine strata of early geological date (Cambrian); and this shows that a depression of the region beneath an ancient sea took place after a long existence as dry land. The extent of the submergence and the area over which the Palaeozoic strata were deposited are unknown; for in consequence of renewed elevation without deformation, erosion in later periods has stripped off an undetermined amount of the covering strata. The valleys by which the uplands are here and there trenched to moderate depth appear to be, in part at least, the work of streams that have been superposed upon the perieplain through the now removed cover of stratified rocks. Glaciation has strongly scoured away the deeply-weathered soils that presumably existed here in preglacial time, revealing firm and rugged ledges in the low hills and swells of the ground, and spreading an irregular drift cover over the lower parts, whereby the drainage is often much disordered; here being detained in lakes and swamps (muskegs) and there rushing down rocky rapids. The region is therefore generally unattractive to the farmer, but it is inviting to the lumberman and the miner.
The Adirondack Mountains .T his rugged district of northern New York may be treated as an outlier in the United States of the Laurentian highlands of Canada, from which it is separated by the St Lawrence Valley. It is of greater altitude (Mt Marcy 5344 ft.) and of much greater relief than the Superior Oldland; its heights decrease gradually to the north, west and south, where it is unconformably overlapped by Palaeozoic strata like those of Minnesota and Wisconsin; it is of more broken structure and form on. the east, where the disturbances of the Appalachian system have developed ridges and valleys of linear trends, which are wanting or but faintly seen elsewhere. (See ADIRONDACKS.)
Region of tile Great LakesThe Palaeozoic strata, already mentioned as lapping on the southern slope of the Superior Olclland and around the western side of the Adirondacks- are but parts of a great area of similar strata, hundreds of feet in thickness, which dec]ine gently southward from the great oldland of the Laurentian highlands of eastern Canada. The strata are the deposits of an ancient sea, which in the earlier stage of geological investigation was thought to be part of the primeval ocean, while the Laurentian highlands were taken to be the first land that rose from the primeval waters. Inasmuch, however, as the floor on which the overlapping strata rest is, like the rest of the Laurentian and Superior Oldland, a worn-down mountain region, and as the lowest member of the sedimentary series usually contains pebbles of the oldiand rocks, the better interpretation of the relation between the two is that the visible oldiand area of to-day is but a small part of the primeval continent, the remainder of which is still buried under the Palaeozoic cover; and that the visible oldiand, far from being the first part of the continent to rise from the primeval ocean, was the last part of the primeval continent to sink under the advancing Palaeozoic seas. When the oldland and its overlap of stratified deposits were elevated again, the overlapping strata must have had the appearance of a coastal plain; but that was long ago; the strata have since then been much eroded, and to-day possess neither the area nor the smooth form of their initial extent. I-fence this district may be placed in the class of ancient coastal plains. As is always the case in the broad denudation of the gently inclined strata of such plains, the weaker layers are worn down in sub-parallel belts of lower land between the oldiand and the belts of more resistant strata, which rise in uplands.
Few better illustrations of this class of forms are to be found than that presented in the district of the Great Lakes. The chief upland belt or cuesta is formed by the firm Niagara limestone, which takes its name from the gorge and falls cut through the upland by the Niagara river. As in all such forms, the Niagara cuesta has a relatively strong slope or infacing escarpment on the side towards the oldland, and a long gentle slope on the other side. Its relief is seldom more than 200 or 300 ft., and is commonly of small measure, but its continuity and its contrast with the associated lowlands worn on the underlying and overlying weak strata suffice to sake it a feature of importance. The cuesta would be straight from east and west if the slant of the strata were uniformly to the south; but the strata are somewhat warped, and hence the course of the cuesta is strongly convex to the north in the middle, gently convex to the south at either end. The cuesta begins where its determining limcstone begins, in west-central New York; there it separates the lowlands that contain the basins of lakes Ontario and Erie; thence it curves to the north-west through the province of Ontario to the belt of islands that divide1 Georgian Bay from Lake Huron; then westward throtigh the land-arm between lakes Superior and Michigan, and south-westward into the narrow points that divide Green Bay from Lake Michigan, and at last westward to fade away again with the thinning out of the limestone; it is hardly traceable across the Mississippi river. The arrangement of the Great Lakes is thus seen to he closely synipathetic with the course of the lowlands worn on the two belts of weaker strata on either side of the Niagara cuesta; Ontario, Georgian Bay and Green Bay occupy depressions in the lowland on the inner side of the cuesta; Erie, Huron and Michigan lie in depressions in the lowland on the outer side. When the two lowlands are traced eastward they become confluent after the Niagara limestone has faded away in central New York, and the single lowland is continued under the name of Mohawk Valley, an east-west longitudinal depression that has been eroded on a belt of relatively weak strata between the resistant crystalline rocks of the Adirondacks on the north and the northern escarpment of the Appalachian plateau (Catskills-Helderbergs) on the south; forming a pathway of great historic and economic importance between the Atlantic seaports and the interior.
In Wisconsin the inner lowland presents an interesting feature in a knob of resistant quartzites, known as Baraboo Ridge, rising from the buried oldland floor through the partly denuded cover of lower Palaeozoic strata. This knob or ridge may be appropriately regarded as an ancient physiographic fossil, inasmuch as, being a monadnock of very remote origin, it has long been preserved from the destructive attack of the weather by burial under sea-floor deposits, and recently laid bare, like ordinary organic fossils of much smaller size, by the removal of part of its cover by normal erosion.
The occurrence of the lake basins in the lowland belts on either side of the Niagara cuesta is an abnormal feature, not to be explained by ordinary erosion, which can produce only valleys. The basins have been variously ascribed to glacial erosion, to obstruction of normal outlet valleys by barriers of glacial drift, and to crustal warping in connection with or independent of the presence of the glacial sheet. No satisfactory solution of this problem has been reached; but the association of the Great Lakes and other large lakes farther north in Canada with the great North American area of strong and repeated glaciation is highly suggestive.
Lake Superior is unlike the other lakes; the greater part of its basin occupies a depression. in the oldland area, independent of the overlap of Palaeozoic strata. The western half of the basin occupies a trough of synclinal structure; but the making of this syndine is so ancient that it cannot be directly connected with the occurrence of the lake to-day. A more reasonable explanation ascribes the lake basin to a geologically modern depression. within the Superior oldland area; but there is at present no direct evidence in favor of this hypothesis. The Great Lakes are peculiar in receiving the drainage of but a sma]l peripheral land area, enclosed by an ill-defined water-parting from the rivers that run to Hudson Bay or the Gulf of St Lawrence on the north and to the Gulf of Mexico on the south.
Large canals and locks on both sides of the Sault (pronounced Soo) Ste Marie in the outlet of Lake Superior are actively used except during three or four winter months. The three lakes of the middle group stand at practically the same level: Michigan and Huron are connected by the Strait of Mackinac (pronounced Mackinaw); Huron and Erie by the St Clair and Detroit rivers, with the small Lake St Clair between them. The navigable depth of these two short rivers is believed to be the result of a slow elevation of the land in the north-east, still in progress, whereby the, waters have risen on their former shores near Detroit. Niagara river, connecting lakes Erie and Ontario, with a fall of 326 ft. (160 ft. at the cataract) in 30 m, is manifestly a watercourse of very modern origin; for a large river would now have a thoroughly matured valley had it long followed its present course; the same is true of the St Lawrence, which in its several rapids and in its subdivision into many channels at the Thousand Islands, presents every sign of youth. Canals on the Canadian side of these unnavigable stretches admit vessels of a considerable size to lakes Ontario and Erie.
The Prairie States.The originally treeless prairies of the upper Mississippi basin began in Indiana and extended westward and north-westward until they merged with the drier region described Leyond as the Great Plains. An eastward extension of the same region, originally tree-covered, extended to central Ohio. Thus the prairies may be described as lying in a general way between the Ohio and Missouri rivers on the south and the Great Lakes on the north. Under the older-fashioned methods of treating physical geography, the prairies were empirically described as level prairies, rolling prairies, and so on. The great advance in the interpretation of land forms now makes it possible to introduce as thoroughly explanatory a description of these fertile plains as of forms earlier familiar, such as sand dunes, deltas and sea cliffs. The prairies are, in brief, a contribution of the glacial period; they consist for the most part of glacial drift, deposited unconformably on an underlying rock surface of moderate or small relief. The rocks here concerned are the extension of the same stratified Palaeozoic formations already described as occurring~in the Appalachian region and around the Great Lakes. They are usually fine-textured limestones and shales, lying horizontal; the moderate or small relief that they were given by mature preglacial erosion is now buried under the drift, but is known by numerous borings for oil, gas and water.
The greatest area of the prairies, from Indiana to North Dakota, consists of till plains, that is, sheets of unstratified drift, 30, 50 or even 100 ft. thick, which cover the underlying rock surface for thousands of square miles (except where postglacial stream erosion has locally laid it bare), and present an extraordinarily even surface. The till is presumably made in part of preglacial soils, but it is more largely composed of rock waste mechanically comminuted by the crccpiiig ice sheets; although the crystalline rocks from Canada and some of the more resistant stratified rocks south of the Great Lakes occur as boulders and stones, a great part of the till has been crushed and ground to a clayey texture. The till plains, although sweeping in broad swells of slowly changing altitude, are often level to the eye, and the view across them stretches to the horizon, unless interrupted by groves of trees along the watercourses, or by belts of low morainic hills. Here and there faint depressions occur, occupied by marshy sloughs, or floored with a rich black soil of pestglacial origin. It is thus by sub-glacial aggradation that the prairies have been leyelled up to a smooth surface, in contrast to the higher and non-glaciated hilly country next south.
The great ice sheets formed terminal moraines around their border at various halting stages; but the morainic belts are of small relief in comparison to the great area of the ice; they rise gently from the till plains to a height of 50, 100 or more feet; they may be one, two or three miles wide; and their hilly surface, dotted over with boulders, contains many small lakes in basins or hollows, instead of streams in valleys. The morainic belts are arranged in groups of concentric loops, convex southward, because the ice sheets advanced in lobes along the lowlands of the Great Lakes; neighboring morainic loops join each other in re-entrants (north-pointing cusps), where two adjacent glacial lobes came together and formed their moraines in largest volume. The discovery of this significant looped arrangement of the morainic belts is the greatest advance in interpretation of glacial phenomena since the first suggestion of a glacial period; it is also the strongest proof that the ice here concerned was a continuous sheet of creeping land ice, and not a discontinuous series of floating icebergs, as had been supposed. The moraines are of too small relief to be shown on any maps but those of the largest scale; yet small as they are, they are the chief relief of the prairie states, and, in association with the nearly imperceptible slopes of the till plains, they determine the course of many streams and rivers, which as a whole are consequent upon the surface form of the glacial deposits.
The complexity of the glacial period and its subdivision into several glacial epochs, separated by interglacial epochs of considerable length (certainly longer than the postglacial epoch) has a structural consequence in the superposition of successive till sheets, alternating with non-glacial deposits, and also a physiographic consequence in the very different amount of normal postglacial erosion suffered by the different parts of the glacial deposits. The southernmost drift sheets, as in southern Iowa and northern Missouri, have lost their initially plain surface and are now maturely dissected into gracefully rolling forms; here the valleys of even the small streams are well opened and graded, and marshes and lakes are wanting: hence these sheets are of early Pleistocene origin. Nearer the Great Lakes the till sheets are trenched only by the narrow valleys of the large streams; marshy sloughs still occupy the faint depressions in the till plains, and the associated moraines have abundant small lakes in their undrained hollows: hence these drift sheets are of late Pleistocene origin.
When the ice sheets fronted on land sloping southward to the Ohio, Mississippi and Missouri rivers, the drift-laden streams flowed freely away from the ice border; and as the streams, escaping from their subglacial channels, spread in broader channels, they ordinarily could not carry forward all their load; hence they acted not as destructive but as constructive agents, and aggraded their courses. Thus local sheets or aprons of gravel and sand are spread more or less abundantly along the outer side of the morainic belts; and long trains of gravel and sands clog the valleys that lead southward from the glaciated to the non-glaciated area. Later when the ice retreated farther and the unloaded streams returned to their earlier degrading habit, they more or less completely scoured out the valley deposits, the remains of which are now seen in terraces on either side of the present flood plains.
When the ice of the last glacial epoch had retreated so far that Its front lay on a northward slope, belonging to the drainage area of the Great Lakes, bodies of water accumulated in front of the ice margin, forming glacio-marginal lakes. The lakes were small at first, and each had its own outlet at the lowest depression in -the height of land to the south; but as the ice melted back, neighboring lakes became confluent at the level of the lowest outlet of the group; the outflowing streams grew in the same proportion and eroded a broad channel across the height of land and far down stream, while the lake waters built sand reefs or carved shore cliffs along their margin, and laid down sheets of clay on their floors. All of these features are easily recognized in the prairie region. The present site of Chicago was determined by an Indian portage or carry across the low divide between Lake Michigan and the headwaters of the Illinois river; and this divide lies on the floor of the former outlet channel of the glacial Lake Michigan. Corresponding outlets are known for the glacial lakes Erie, Huron and Superior, and for a very large sheet of water, named Lake Agassiz, which once overspread a broad till plain in northern Minnesota and North Dakota. The outlet of this glacial lake, called river Warren, eroded a large channel in which the Minnesota river, of to-day is an evident misfit.
Certain extraordinary features were produced when the retreat of the ice sheet had progressed so far as to open an eastward outlet for the marginal lakes along the depression between the northward slope of the Appalachian plateau in west-central New York and the southward slope of the melting ice sheet; for when this eastward outlet came to be lower than the south-westward outlet across the height of land to the Ohio or Mississippi river, the discharge of the marginal lakes was changed from the Mississippi system to the Hudson system. Many well-defined channels, cutting across the north-sloping spurs of the plateau in the neighborhood of Syracuse, NY., mark the temporary paths of the ice-bordered outlet river. Successive channels are found at lower and lower levels on the plateau slope, thus indicating the successive courses taken by the lake outlet as the ice melted farther and farther back. On some of these channels deep gorges were eroded heading in temporary cataracts which exceeded Niagara in height but not in breadth; the pools excavated by the plunging waters at the head of the gorges are now occupied by little lakes. The most significant stage in this series of changes occurred when the glacio-marginal lake wateis were lowered so that the long cuesta of Niagara limestone was laid bare in western New York; the previously confluent waters were then divided into two lakes; the higher one, Erie, supplying the outfiowing Niagara river, which poured its waters down the escarpment of the cuesta to the lower lake, Ontario, whose outlet for a time ran down the Mohawk Valley to the Hudson: thus Niagara falls began. (See NIAGARA.)
Many additional features associated with the glacial period might be described, but space can be given to four only. In certain districts the subglacial till was not spread out in a smooth plain, but accumulated in elliptical mounds, 100 or 200 ft. high, half a mile or a mile long, with axes parallel to the direction of the ice motion as indicated by striae on the underlying rock floor; these hills are known by the Irish name, drumlins, used for similar hills in north-western Ireland. The most remarkable groups of drumlins occur in western New York, where their number is estimated at over 6000, and in southern Wisconsin, where it is placed at 5000. They completely dominate the topography of their districts.
A curious deposit of an impalpably fine and unstratified silt, known by the German name bess, lies on the older drift sheets near the larger river courses of the upper Mississippi basin. It attains a thickness of 20 ft. or more near the rivers and gradually fades away at a distance of ten or more miles on either side. It is of inexhaustible fertility, being in this as well as in other respects closely like the bess in China and other parts of Asia, as well as in Germany. It contains land shells, and hence cannot be attributed to marine or lacustrine submergence. The best explanation suggested for bess is that, during certain phases of the glacial period, it was carried as dust by the winds from the flood plains of aggrading rivers, and slowly deposited on the neighboring grass-covered plains.
South-western Wisconsin and parts of the adjacent states of Illinois, Iowa and Minnesota are known as the driftless area, because, although bordered by drift sheets and moraines, it is free from glacial deposits. It must therefore have been a sort of oasis, when the ice sheets from the north advanced past it on the east and west and joined around its southern border. The reason for this exemption from glaciation is the converse of that for the southward convexity of the morainic loops; for while they mark the paths of greatest glacial advance along lowland troughs (lake basins), the driftless area is a district protected from ice invasion by reason of the obstruction which the highlands of northern Wisconsin and Michigan (part of the Superior oldland~ offered to glacial advance.
The course of the upper Mississippi river is largely consequent i upon glacial deposits. Its sources are in the morainic lakes in northern Minnesota; Lake Itasca being only one of many glacial lakes which supply the headwater branches of the great river. The drift deposits thereabouts are so heavy that the present divides between the drainage basins of Hudson Bay, Lake Superior and the Gulf of Mexico evidently stand in no very definite relation to the preglacial divides. The course of the Mississippi through Minnesota is largely guided by the form of the drift cover. Several rapids and the Falls of St Anthony (determining the site of Minneapolis) are signs of immaturity, resulting from superposition through the drift on the under rock. Farther south, as far as the entrance of the Ohio, the Mississippi follows a rock-walled valley 300 to 400 ft. deep, with a flood-plain 2 to 4 m. wide; this valley seems to represent the path of an enlarged early-glacial Mississippi, when much precipitation that is to-day discharged to Hudson Bay and the Gulf of St Lawrence was delivered to the Gtilf of Mexico, for the curves of the present river are of distinctly smaller raditis than the curves of the valley. Lake Pepin (30 m. below St Paul), a picturesque expansion of the river across its flood-plain, is due to the aggradation of the valley floor where the Chippewa river, coming from the north-east, brought an overload of fluvio-glacial drift. Hence even the father of waters, like so many other rivers in the Northern states, owes many of its features more or less directly to glacial action.
The fertility of the prairies is a natural consequence of their origin. During the mechanical comminution of the till no vegetation was present to remove the minerals essential to plant growth, as is the case in the soils of normally weathered and dissected peneplains, such as the Appalachian piedmont, where the soils, though not exhausted by the primeval forest cover, are by no means ~so rich as the till sheets of the prairies. Moreover, whatever the rocky understructure, the till soil has been averaged by a thorough mechanical mixture of rock grindings; hence the prairies are continuously fertile for scores of miles together.
The true prairies, when first explored, were covered with a rich growth of natural grass and annual flowering plants. To-day they are covered with farms. The cause of the treelessness has been much discussed. It does not seem to lie in peculiarities of temperature or of precipitation; for trees thrive where they are properly planted on the prairies; every town and farm to-day has its avenues and groves of trees; but it should be noted that west of the Mississippi river increasing aridity becomes an important factor, and is the chief cause of the treelessness of the Great Plains (see below). The treelessness of the prairies cannot be due to insufficient time for tree invasion since glacial evacuation; for forests cover the rocky uplands of Canada, which were occupied by ice for ages after the prairies were laid bare. A more probable cause is found in the fineness of the prairie soil, which is inimical to the growth of young trees in competition with the grasses and annual plants. Prairie fires, both of natural and artificial origin, are also a contributive cause; for young trees are exterminatedby fires, but annual plants soon reappear.
The Gulf Coastal Plain.The westward extension of the Atlantic coastal plain around the Gulf of Mexico carries with it a repetition of certain features already described, and the addition of several new ones. As in the Atlantic coastal plain, it is only the lower, seaward part of this region that deserves the name of plain, for there alone is the surface unbroken by hills or valleys; the inner part, initially a plain by reason of its essentially horizontal (gently seaward-sloping) structure, has been converted by mature dissection into an elaborate complex of hills and valleys, usually of increasing altitude and relief as one passes inland.
The special features of the Gulf Plain are the peninsular extension of the plain in Florida, the belted arrangement of relief and soils in Alabama and in Texas, and the Mississippi embayment or inland extension of the plain half-way up the course of the Mississippi river, with the Mississippi flood plain there included.
A broad, low crustal arch extends southward at the junction of the Atlantic and Gulf coastal plains; the emerged half of the arch, constitutes the visible lowland peninsula of Florida; the submerged half extends westward under the shallow Florida. overlapping waters of the Gtmlf of Mexico. The northern part of the peninsula is composed largely of a weak limestone; here much of the lowland drainage is underground, forming many sink-holes (swallOwholes). Many small lakes in the lowland appear to owe their basins to the solution of the limestones. Valuable phosphate deposits occur in certain districts. The southern part of the state includes the Everglades (qv.), a large area of low, flat, marshy land, overgrown with tall reedy grass, a veritable wilderness; thus giving Florida an unenvied first rank among the states in marsh area. The eastern coast is fringed by long-stretching sand reefs, enclosing lagoons so narrow and continuous that they are popularly called rivers. At the southern end of the peninsula is a series of coral islands, known as keys; they appear to be due to the forward growth of corals and other lime-secreting organisms towards the strong current of the Gulf Stream, by which their food is supplied:
the part of the peninsula composed of coral reefs is less than has been formerly supposed. The western coast has fewer and shorter off-shore reefs; much of it is of minutely irregular outline, which seems to be determined less by the work of the sea than by the forward growth of mangrove swamps in the shallow salt water.
A typical example of a belted coastal plain is found in Alabama and the adjacent part of Mississippi. The plain is here about 1.50 m. wide. The basal formation if chiefly a weak limestone, which has been stripped from its original Alabama. innermost extension and worn down to a flat inner lowland of rich black soil, thus gaining the name of the black belt. The lowland is enclosed by an upland or cuesta, known as Chunnenugga Ridge, sustained by partly consolidated sandy strata; the upland, however, is not continuous, and hence should be described as a maturely dissected cuesta. It has a relatively rapid descent toward the inner lowland, and a very gradual descent to the coast prairies, which become very low, flat and marshy before dipping under the Gulf waters, where they are generally fringed by off-shore reefs.
The coastal plain extends 500 m. inland on the axis of the Mississippi embayment. Its inner border affords admirable examples of topographical discordance where it sweeps north-westward square across the trend of the piedmont belt, the ridges and valleys, and the plateau of the Appalachians, which are all terminated by dipping gently beneath the unconformable cover of the coastal The, lain strata. In the same way the western side of the em- Mississippi ~ayment, trending south and south-west, passes along the Emba.vmeni.lower south-eastern side of the dissected Ozark plateau of southern Missouri and northern Arkansas, which in many ways resembles the Appalachian plateau, and along the eastern end of the Massern ranges of the Ouachita mountain system in central Arkansas, which in geological history and topographical form present many analogies with the ridges and valleys of the Appalachians; and as the coastal plain turns westward to Texas it borders the Arbuckle hills in Oklahoma, a small analogue of the crystalline Appalachian belt. In the embayment of the coastal plain some low cuesta-like belts of hills with associated strips of lowlands suggest the features of a beltedcoastal plain; the hillybeltordissected cuesta determined by the Grand Gulf formation in western Mississippi is the most distinct. Important salt deposits occur in the coastal plain strata near the coast. The most striking feature of the embayment is the broad valley which the Mississippi has eroded across it.
The lower Mississippi is the truck in which three large rivers Join; the chief figures (approximate only) regarding them are as follows: Drainage Area Percentage of (square miles). Total Discharge.
Upper Mississippi. 170,000 18
Ohio 210,000 31
Missouri 530,000 14
The small proportion of total water volume supplied from the great Missouri basin is due to the light precipitation in that region. The h L lower Mississippi receives no large tributary from the T e ower east, but two important ones come from the west; the Mississippi Arkansas drainage area being a little less than that River. of the Ohio, and the basin of the Red River of Louisiana being about half as large. The great river thus constituted drains an area of about 1,250,000 sq. m., or about one-third of the United States; and discharges 75,000 cub. yds. of water per second, or 785,190,000,000 cubic yds. per annum, which corresponds roughly to one quarter of the total precipitation on its drainage basin. Its load of land waste (see I. C. Russell, Rivers of North America) is as follows: In suspension.. 6,718,694,400 cub. ft. or 241 ft. deep over 1 sq. in.
Sweptalongbottom 750,000,000 ,, ,, 26 ,, ,, I
In soltition. -. 1,350,000,000 ,, ,, 45 ,, ,, I
Average annual removal of waste from entire basin, th in. or 1 ft. in 4000 years.
The head of the coastal plain embayment is near the junction of the Ohio and the Mississippi. Thence southward for 560 m. the great river flows through the semi-consolidated strata of the plain, in which it has eroded a valley, 40 or 50 in. wide, and 29,700 sq. m. in area, enclosed by bluffs one or two hundred feet high in the northern part, generally decreasing to the southward, but with local increase of height associated with a decrease in flood plain breadth on the eastern side where the Grand Gulf cuesta is traversed. This valley in the coastal plain, with the much narrower rock-walled valley of the upper river in the prairie states, is the true valley of the S3ississippi river; but in popular phrase the Mississippi valley is taken to include a large central part of the Mississippi drainage basin. The valley floor is covered with a flood plain of fine silt, having a southward slope of only half a foot to a mile. The length of the river itself, from the Ohio mouth to the Gulf, is, owing to its windings, about 1060 ni.; its mean fall is about 3 in. in a mile. On account of the rapid deposition of sediment near the main channel at times of overflow, the flood plain, as is normally the case on mature valley floors, has a lateral slope of as much as 5, 10, or even 12 ft. in the first mile from the river; but this soon decreases to a less amount. Hence at a short distance from the river the flood plain is often swampy, unless its surface is there aggraded by the tributary streams: for this reason Louisiana, Arkansas and Mississippi rank next after Florida in swamp area.
The great river receives an abundant load of silt from its tributaries, and takes up ano lays down silt from its own bed and banks with every change of velocity. The swiftest current te,-ids, by reason of centrifugal force, to follow the outer side of every significant curve in the channel; hence the concave bank, against which the rapid current sweeps, is worn away; thus any chance irregularity is exaggerated, and in time a series of large serpentines or meanders is developed,, the most-symmetrical examples at present being those near Greenville, Miss. The growth of the meanders tends to give the river continually increasing length; but this tendency is counteracted by the sudden occurrence of cut-offs from time to time, so that a fairly constant length is maintained.
The floods of the Mississippi usually occur in spring or aummer; Owing to the great size of the drainage basin, it seldom happens that the three upper tributaries are in flood at the same time; the coincident occurrence of floods in only two tributaries is of serious import in the lower river, which rises 30, 40, or occasionally 50 ft. The abundant records by the Mississippi River Commission and the United States Weather Bureau (by which accurate and extremely useful predictions of floods in the lower river course are made, on the basis of the observed rise in the tributaries) demonstrate a num~ bar of interesting features, of which the chief are as follows: the fall of the river is significantly steepened and its velocity isaccelerated down stream from the point of highest rise; conversely, the fall and the velocity are both diminished up stream from the same point.
The load of silt borne down stream by the river finally, after many halts on the way, reaches the waters of the Gulf, where the decrease of velocity, aided by the salinity of the sea water, causes the formation of a remarkable delta, leaving less aggraded areas as shallow lakes (Lake Pontchartrain on the east, and Grand Lake on the west of the river). The ordinary triangular form of deltas, due to the smoothing of the delta front by sea action, is here wanting, because of the weakness of sea action in comparison with the strength of the current in each of the four distributaries or passes into which the river divides near its mouth. (See MISSISSIPPI RIVER.)
After constriction from the Mississippi embayment to 250 m. in western Louisiana, the coastal plain continues south-westward with this breadth until it narrows to about 130 in. in The Texas southern Texas near the crossing of the Colorado river, ~
(of Texas); but it again widens to 300 m. at the ~ a national boundary as a joint effect of ernbayment up the valley of the Rio Grande and of the seaward advance of this rivers rounded delta front: these several changes take place in a distance of about 500 in., and hence include a region of over ioo,00o sq. m. less than half of the large state of Texas. A belted arrangement of relief s and soils, resulting from differential erosion on strata of unlike composition and resistance, characterizes almost the entire area of the coastal plain. Most of the plain is treeless prairie, but the sandier belts are forested; two of them are known as cross timbers, because their trend is transverse to the general course of the main consequent rivers. An inland extension from the coastal plain in north-central Texas leads to a large cuesta known as Grand Prairie (not structurally included in the coastal plain), upheld at altitudes of 1200 or 1300 ft. by a resistant Cretaceous limestone, which dips gently seaward; its scalloped inland-facing escarpment overlooks a denuded central prairie region of irregular structure and form; its gentle coastward slope (16 ft. to a mile) is dissected by many branching consequent streams; in its southernpart, as it ap~iroaches the Colorado river the cuesta is dissected into a belt of discontinuous hills. The western cross timbers follow a sandy belt along the inner base of the ragged escarpment of Grand Prairie; the eastern cross timbers follow another sandy belt in the lowland between the eastern~ slope of Grand Prairie and the pale western escarpment of the next eastward and lower Black Prairie cuesta. This cuesta is supported at an altitude of 700 ft. or less by a chalk formation, which gives an infacing slope some 200 ft. in height, while its gently undulating or rolling seaward slope (2 or 3 ft. in a mile), covered with marly strata and rich black soil, determines an important cotton district. Then comes the East Texas timber belt, broad in the north-east, narrowing to a point before reaching the Rio Grande, a low and thoroughly dissected cuesta of sandy Eocene strata; and this is followed by the Coast Prairie, a very young plain, with a seaward slope of less than 2 ft. in a mile, its smooth surface interrupted only by the still more nearly level flood plains of the shallow, consequent river valleys. Near the Colorado river the dissected cuesta of the Grand Prairie passes southward, by a change to a more nearly horizontal structure, into the dissected Edwards plateau (to be referred to again as part of the Great Plains), which terminates in a maturely dissected fault scarp, 300 or 400 ft. in height, the northern boundary of the Rio Grande embayment. From the Colorado to the Rio Grande, the Black Prairie, the timber belt and the Coast Prairie merge in a vast plain, little differentiated, overgrown with chaparral (shrub-like trees, often thorny), widening eastward in the Rio Grande delta, and extending southward into Meico.
Although the Coast Prairie is a sea bottom of very modern uplift, it appears already to have suffered a slight movement of depression, for its small rivers all enter embayments; the larger rivers, however, seem to have counteracted the encroachment of the sea on the land by a sufficiently active delta building, with a resulting forward growth of the land into the sea. The Mississippi has already been mentioned as rapidly building forward its digitate delta; the Rio Granide, next in size, has built its delta about 50 m. forward from the general coast-iine, but this river being much smaller than the Mississippi, its delta front is rounded by seashore agencies. In front of the Brazos and the Colorado, the largest of the Texan rivers, the coast-line is very gently bowed forward, as if by delta growth, and the sea touches the mainland in a nearly straight shore line. Nearly all the rest of the coast is fringed by off-shore reefs, built up by waves from the very shallow sea bottom; in virtue of weak tides, the reefs continue in long unbroken stretches between the few inlets.
The Great Plains.A broad stretch of country underlaid by nearly horizontal strata extends westward from the 97th meridian to the base of the Rocky Mountains, a distance of from 300 to 500 in., and northward from the Mexican ,boundary far into Canada. This is the province of the Great Plains. Although the altitude of plains increases gradually from,6oo or 1200 ft. on the east to 4000, 5000 or 6000 ft. near the mountains, the local relief is generally small; the sub-arid climate excludes tree growth and opens far-reaching views. The plains are by no means a simple unit; they are of diverse structure and of various stages of erosional development; they are occasionally interrupted by buttes and escarpments; they are frequently broken by valleys: yet on the whole a broadly extended surface of moderate relief so often prevails that the name, Great Plains, for the region as a whole is well deserved. The western boundary of the plains is usually well defined by the abrupt ascent of the mountains. The eastern boundary of the plains is more climatic than topographic. The line of 20 in. of annual rainfall trends a little east of northward near the 97th meridian, and if a boundary must be drawn where nature presents only a gradual transition, this rainfall line may be taken to divide the drier plains from the moister prairies. The plains may be described in northern, intermediate, central and southern sections, in relation to certain peculiar features.
The northern section of the Great Plains, north of latitude 44, including eastern Montana, north-eastern Wyoming and most of the Dakotas, is a moderately dissected peneplain, one of the best examples of its class. The strata here are Cretaceous or early Tertiary, lying nearly horizontal. The surface is shown to be a plain of degradation by a gradual ascent here and there to the crest of a ragged escarpment, the cuesta-remnant of a resistant stratum; and by the presence of lava-capped mesas and dike-ridges, surmounting the general level by 500 ft. or more and manifestly demonstrating the widespread erosion of the surrounding plains. All these reliefs are more plentiful towards the mountains in central Montana. The peneplain is no longer in the cycle of erosion that witnessed its production; it appears to have suffered a regional elevation, for the riversthe upper Missouri and its branchesno longer flow on the surface of the plain, but in well graded, maturely opened valleys, several hundred feet below the general level. A significant exception to the rule of mature valleys occurs, however, in the case of the Missouri, the largest river, which is broken by several falls on hard sandstones about 50 m. east of the mountains. This peculiar feature is explained as the result of displacement of the river from a better graded preglacial valley by the Pleistocene ice-sheet, which here overspread the plains from the moderately elevated Canadian highlands far on the north-east, instead of from the much higher mountains near by on the west. The present altitude of the plains near the mountain base is 4000 ft.
The northern plains are interrupted by several small mountain areas. The Black Hills, chiefly in western South Dakota, are the largest group: they rise like a large island from the sea, occupying an oval area of about 100 m. north-south by 50 m. east-west, reaching an altitude in Harney Peak of 7216 ft., and an effective relief over the plains of 2000 or 3000 ft. This mountain mass is of flat-arched, dome-like structure, now well dissected by radiating consequent streams, so that the weaker uppermost strata have been eroded down to the level of the plains where their upturned edges are evenly truncated, and the next following harder strata have been sufficiently eroded to disclose the core of underlying crystalline rocks in about half of the domed area.
In the intermediate section of the plains, between latitudes 44 and 42, including southern South Dakota and northern Nebraska, the erosion of certain large districts is peculiarly elaborate, giving rise to a minutely dissected form, known as bad lands, with a relief of a few hundred feet, This is due to several causes: first, the dry climate, which prevents the growth of a grassy turf; next, the fine texture of the Tertiary strata in the had land districts; and consequently the success with which every little nIl, at times of rain, carves its own little valley. Travel across the bad lands is very fatiguing because of the many small ascents and descents; and it is from this that their name, mauvaises terres pour traverser, was given by the early French voyageurs.
The central section of the Great Plains, between latitudes 42 and 36, occupying eastern Colorado and western Kansas, is, briefly stated, for the most part a dissected fluviatile plain; that is, this section was once smoothly covered with a gently sloping plain of gravel and sand that had been spread far forward on a broad denuded area as a piedmont deposit by the rivers which issued from the mountains; and since then it has been more or less dissected by the erosion of valleys. The central section of the plains thus presents a marked contrast to the northern section; for while the northern section owes its smoothness to the removal of local gravels and sands from a formerly uneven surface by the action of degrading rivers and their inflowing tributaries, the southern section owes its smoothness to the deposition of imported gravels and sands upon a previously I uneven surface by the action of aggrading rivers and their outgoing distributaries. The two sections are also unlike in that residual eminences still here and there surmount the peneplain of the northern section, while the fluviatile plain of the central section completely buried the pre-existent relief. Exception to this statement must be made in the south-west, close to the mountains in southern Colorado, where some lava-capped mesas (Mesa de Maya, Raton Mesa) stand several thousand feet above the general plain level, and thus testify to the widespread erosion of this region before it was aggraded.
The southern section of the Great Plains, between latitudes 351/2 and 2Q~ ~. lies in eastern Texas and eastern New Mexico: like the central section it is for the most part a dissected fluviatile plain, but the lower lands which surround it on all sides place it in so strong relief that it stands up as a table-land, known from the time of Mexican occupation as the Llano Estacado. It measures roughly Iso m. east-west and 400 m. north-south, but it is of very irregulal outline, narrowing to the south. Its altitude is 5500 ft. at the highest western point, nearest the mountains whence its gravels were supplied; and thence it slopes south-eastward at a decreasing rate, first about 12 ft., then about 7 ft. in a mile, to its eastern and southern borders, where it is 2000 ft. in altitude: like the High Plains farther north, it is extraordinarily smooth; it is very dry, except for occa sional shallow and temporary water sheets after rains. The Llano is separated from the plains on the north by the mature consequent valley of the Canadian river, and from the mountains on the west by the broad and probably mature valley of the Pecos river. On the east it is strongly undercut by the retrogressive erosion of the headwaters of the Red, Brazos and Colorado rivers of Texas, and presents a ragged escarpment, 500 to 800 ft. high, overlooking the central denuded area of that state; and there, between the Brazos and Colorado rivers, occurs a series of isolated outliers capped by a limestone which underlies both the Llano on the west and the Grand Prairies cuesta on the east. The southern and narrow part of the table-land, called the Edwards Plateau, is more dissected thanthe rest, and falls off to the south in a frayed-out fault scarp, as already mentioned, overlooking the coastal plain of the Rio Grande embayment. The central denuded area, east of the Llano, resembles the east-central section of the plains in exposing older rocks; between these two similar areas, in the space limited by the Canadian and Red rivers. rise the subdued forms of the Wichita MountaiIis in Oklahoma, the westernmost member of the Ouachita system.
The Cordilleran Region.From the western border of the Great Plains to the Pacific coast, there is a vast elevated area, occupied by mountains, plateaus and intermont plains. The intermont plains are at all altitudes from sea-level to 4000 ft.; the plateaus from 5000 to 10,000 ft.; and the mountains from 8000 to 14,000 ft. The higher mountains are barren from the cold of altitude; the timber line in Colorado stands at 11,000 to 12,000 ft.
The chief provinces of the Cordihleran region are: The Rocky Mountain system and its basins, from northern New Mexico northward, including all the mountains from the front ranges bordering on the plains to the Uinta and Wasatch ranges in Utah; the Pacific ranges including the Sierra Nevada of California, the Cascade range of Oregon and Washington, and the Coast range along the Pacific nearly to the southern end of California; and a great intermediate area, including in the north the Columbian lava plains and in the south the large province of the Basin ranges, which extends into Mexico and widens from the centre southward, so as to meet the Great Plains in eastern New Mexico, and to extend to the Pacific coast in southern California. There is also a province of plateaus between the central part of the Basin ranges and the southern part of the Rocky Mountains. An important geological characteristic of most of the Cordilferan region is that the Carboniferous strata, which in western Europe and the eastern United States contain many coal seams, are represented in the western United States by a marine limestone; and that the important unconformity which in Europe and the eastern United States separates the Palaeozoic and Mesozoic eras does not occur in the western United States, where the formations over a great area follow in conformable sequence from early Palaeozoic through the Mesozoic.
The Rocky Mountains begin in northern Mexico, where the axial crystalline rocks rise to 12,000 ft. between the horizontal structures of the plains on the east and the plateaus on the west. The Pocky The upturned stratified formations wrap around the Mountains. flanks of the range, with ridges and valleys formed on their eroded edges and drained southward by the Pecos river to the Rio Grande and the Gulf of Mexico. The mountains rapidly grow wider and higher northward, by taking on new complications of structure and by including large basins between the axes of uplift, tintil in northern Colorado and Utah a complex of ranges has a breadth of 300 m., and in Colorado alone there are 40 summits over 14,000 ft. in altitude, though none rises to 14,500. Then turning more to the north-west through Wyoming, the ranges decrease in breadth and height; in Montana their breadth is not more than 150 m .,and only seven summitsexceed 11,000 ft. (one reaching 12,834).
As far north as the gorge of the Missouri river in Montana, the Front range, facing the Great Plains, is a rather simple uplift, usually formed by upturning the flanking strata, less often by a fracture. Along the eastern side of the Front Range in Colorado most of the upturned stratified formations have been so well worn down that, except for a few low piedmont ridges, their even surface may now be included with that of the plains, and the crystalline core of the range is exposed almost to the mountain base. Here the streams that drain the higher areas descend to the plains through narrow canyons in the mountain border, impassable for ordinary roads and difficult of entrance even by railways; a well-known example is the gorge of Clear Creek east of the Georgetown mining district. The crystalline highlands thereabouts, at altitudes of 8000 to 10,000 ft., are of so moderate a relief as to suggest that the mass had stood much lower in a former cycle of erosion and had then been worn down to rounded hills; and that since uplift to the present altitude the revived streams of the current cycle of erosion have not entrenched themselves deep enough to develop strong relief. This idea is confirmed 80 m. farther south, where Pikes Peak (14,108 ft.), a conspicuous landmark far out on the plains, has every appearance of being a huge monadnock, surmounting a rough peneplain of 10,000 ft. in general elevation. The idea is still better confirmed farther north in Wyoming, where the Laramie Range, flanked with upturned strata on the east and west, is for the most part a broad upland at altitudes of 7000 or 8000 ft., with no strong surmounting summits, and as yet no deep carved valleys. Here the first of the Pacific railways chose its pass. When the summit is reached, the traveller is tempted to ask, Where are the mountains? so small is the relief of the upland surface. This low range turns westward in a curve through the Rattlesnake Mountains towards the high Wind River Mountains (Gannett Peak, 3,775 ft.), an anticlinal range within the body of the mountain system, with flanking strata rising well on the slopes. Flanking strata are even better exhibited in the Bighorn Mountains, the front range of northern Wyoming, crescentic in outline and convex to the northeast, like the Laramie Range, but much higher; here heavy sheets of limestone arch far up towards the range crest, and are deeply notched where consequent streams have cut down their gorges.
Farther north in Montana, beyond the gorge of the Missouri river, the structure of the Front Range is altogether different; it is here the carved residual of a great mass of moderately bent Palaeozoic strata, overthrust eastward upon the Mesozoic strata of the plains; instead of exposing the oldest rocks along the axis and the youngest rocks low down on the flanks, the younger rocks of the northern range follow its axis, and the oldest rocks outcrop along its eastern flanks, where they override the much younger strata of the plains; the harder strata, instead of lapping on the mountain flanks in great slab-like masses, as in the Bighorns, form out-facing scarps, which retreat into the mountain interior where they are cut down by outfiowing streams.
The structure of the inner ranges is so variable as to elude simple description; but mention should be made of the Uinta range of broad anticlinal structure in north-east Utah, with east-west trend, as if corresponding to the east-west Rattlesnake Mountains, already named. The \Vasatch Range, trending north-south in central Utah, is peculiar in possessing large east-West folds, which. are seen in cross-section in the dissected western face of the range, becatise the whole mass is there squarely cut off by a great north-south fault with down-throw to the Basin Range province, the fault face being elaborately carved.
Volcanic action has been restricted in the Rocky Mountains proper. West Spanish Peak (I~l,62o ft.), in the Front Range of southern Colorado, may be mentioned as a fine example of a deeply dissected volcano, originally of greater height, with many unusually strong radiating dike-ridges near its denuded flanks. Iii north-western Wyoming there are extensive and heavy lava sheets, uplifted and dissected, and crowned with a few dissected volcanoes. It is in association with this field of extinct volcanic activity that a remarkable group of geysers and hot springs has been developed, from which the Yellowstone river, a branch of the Missouri, flows northeastward, and the Snake river, a branch of the Columbia, flows south-westward. The geyser district is held as a national domain, the Yellowstone Park.
Travellers whose idea of picturesqueness is based upon the abnormally sharpened peaks of the ice-sculptured Alps are disappointed with the scenery of the central and southern ranges of the Rocky Mountains. It is true that many of these ranges are characterized by the rounded tops and the rather evenly slanting, waste-covered slopes which ncrmally result from the long-continued action of the ordinary agencies of erosion; that they bear little snow in summer and are practically wanting in glaciers; that forests are often scanty on the middle and lower slopes, the mord so because of devastation by fires; and that the general impression of great altitude is much weakened because the mountains are seen from a base which itself is 5000 or 6000 ft. above sea-level. Nevertheless the mountains are of especial interest to the physiographer who wishes to make a comparative study of land forms as affected by normal and by glacial sculpture, in order to give due attention to process as well as to structure and stage in the analysis and description of mountain topography. A journey along the range from south to north reveals most strikingly a gradual increase - in the share of sculpture due to Pleistocene glaciers. In New Mexico, if glaciers were formed at all in the high valleys, they were so small as not greatly to modify the more normal forms. In central Colorado and Wyoming, where the mountains are higher and the Pleistocene glaciers were larger, the valley heads were hollowed out in well-formed cirques, often holding small lakes; and the mountain valleys were enlarged into U-shaped troughs as far down as the ice reached, with hanging lateral valleys oii the way. Different stages of cirque development, with accompanying transformation of ioountain shape, are finely illustrated in several ranges around the headwaters of the Arkansas river in central Colorado, where the highest summit of the Ro~k~ Mountains is found (Mt Massive, 14,424 ft., in the Sawatch range); and perhaps even better in the Bighorn range of Wyoming. In this central region, however, it is only by way of exception that the cirques were so far enlarged by retrogressive glacial erosion as to sharpen the preglacial dome-like summits into acute peaks; and in no case did glacial action here extend down to the plains at the eastern base of the mountains; but the widened, trough-like glaciated valleys frequently descend to the level of the elevated intermont basins, where moraines were deployed forward on the basin floor. The finest examples of this kind are the moraines about Jackson Lake on the basin floor east of the Teton Range (Grand Teton, 13,747 ft.), a superb north-south range which lies close to the meridional boundary line between Wyoming and Idaho. Farther north in Montana, in spite of a decrease of height, there are to-day a few small glaciers with snowfields of good size; and, here the effects of sculpture by the much larger Pleistocene glaciers are seen in forms of almost alpine strength.
The intermont basins which so strongly characterize the Rocky Mountain system are areas which have been less uplifted than the enclosing ranges, and have therefore usually become the depositories of waste from the surrounding mountains.
Some of the most important basins may be mentioned. San Luis Valley is an oval basin about 60 m. long near the southern end of the mountain system in New Mexico and Colorado; its level, treeless floor, at an altitude of 7000 ft~. is as yet hardly trenched by the Rio Grande, which escapes through an impassable canyon south-, ward on its way to the Gulf of Mexico. The much smaller basin of the upper Arkansas river in Colorado is well known because the Royal (;orge, a very narrow cleft by which the river escapes through the Front Range to the plains, is followed by a railroad at riverlevel. South Park, directly west of Pikes Peak, is one of the highest basins (nearly 10,000 ft.), and gains its name from the scattered, park-like growth of large pine trees; it is drained chiefly by the South Platte river (Missouri-Mississippi system), through a deep gorge in the dissected mass of the plateau-like Front Range. The Lararnie Plains and the Green river basin, essentially a single structural basic between the east-west ranges of Rattlesnake Mountains on the north and the Uinta Range on the south, measuring roughly 260 m. east-west by Too m. north-south, is the largest intermont basin; it is well known from being traversed through its greatest length by the Union Pacific railway. Its eastern part is drained north-eastward through a gorge that separates the Laramie and Rattlesnake (Front) ranges by the North Platte river to the Missouri-Mississippi; its western part, where the basin floor is much dissected, often assuming a bad-land expression, is drained southward by the Green river, through a deep canyon in the Uinta Ran~e to the Colorado river and then to the Pacific. The Bighorn basin has a moderately dissected floor, drained north-eastward by Bighorn river through a deep canyon in the range of the same name to the Missouri. Several smaller basins occur in Montana, all somewhat dissected and drained through narrow gorges and canyons by members of the Missouri system.
The Plateau province, next west of the southern Rocky Mountains, is characterized for the most part by large-textured forms, developed on a great thickness of nearly horizontal Palaeozoic, The Plateau Mesozoic and Tertiary formations, and by a dry climate. provpee The province was uplifted and divided into great blocks by faults or monoclinal flexures and thus exposed to long-lasting denudation in a mid-Tertiary cycle of erosion; and then broadly elevated again, with renewed movement on some of the fault lines; thus was introduced in late Tertiary time the current cycle of erosion in which the deep canyons of the region have been trenched. The results of the first cycle of erosion are seen in the widespread exposure of the resistant Carboniferous limestone as a broad platform in the south-western area of greater uplift through central Arizona, where the higher formations were worn away; and in the development of a series of huge, south-facing, retreating escarpments of irregular outline on the edges of the higher formations farther north. Each escarpment stands forth where a resistant formation overlies a weaker one; each escarpment is separated from the next higher one by a broad step of weaker strata. A wonderful series of these forms occurs in southern Utah, where in passing northward from the Carboniferous platform one ascends in succession the Vermilion Cliffs (Triassic sandstones), the ViThite Cliffs (Jurassic sandstones, of remarkably cross-bedded structure, interpreted the dunes of an ancient desert), and finally the Pink Cliffs (Eocene strata of fluviatile and lacustrine origin) of the high, forested plateaus. Associated with these irregular escarpments are occasional rectilinear ridges, the work of extensive erosion on monoclinal structures, of whick Echo Cliffs, east of the Painted Desert (so called from its manycoloured sandstones and clays), is a good example.
With the renewal of uplift by which the earlier cycle of erosion was interrupted and the present cycle introduced, inequalities of surface due to renewed faulting were again introduced; these still appear as cliffs, of more nearly rectilinear front than the retreating escarpments formed in the previous cycle. These cliffs are peculiar in gradually passing from one formation to another, and in having a height dependent on the displacement of the fault rather than on the structures in the fault face; they are already somewhat battered and dissected by erosion. The most important line of cliffs of this class is associated with the western and southern boundary of the plateau province, where it was uplifted from the lower ground. The few rivers of the region must have reached the quiescence of old age iii the earlier cycle, but were revived by uplift to a vigorous youth in the current cycle; and it is to this newly introduced cycle of physiographic evolution that the deep canyons of the Plateau province are due. Thus the Virgin river, a northern branch of the Colorado, has cut a vertical slit, 1000 ft. deep, hardly wider at the top than at the bottom, in the heavy Triassic sandstones of southern Utah; but the most famous example is the Grand Canyon (qv.) of Arizona, eroded by the Colorado river across the uplifted platform of Carboniferous limestone.
During the current cycle of erosion, several of the faults, whose scarps had been worn away in the previous cycle, have been brought to light again as topographic features by the removal of the weak strata along one side of the fault line, leaving the harder strata on the other side in relief; such scarps are known as fault-line scarps, in distinction from the original fault scarps. They are peculiar in having their altitude dependent on the depth of revived erosion, instead of the amount of faulting, and they are sometimes topographically reversed, in that the revived scarp overlooks a lowland worn on a weak formation in the upheaved fault-block. Another consequence of revived erosion is seen in the occurrence of great landslides, where the removal of weak (Permian) clays has sapped the face of the Vermilion Cliffs (Triassic sandstone), so that huge slices of the cliff face have slid down and forward a mile or two, all shattered into a confused tumult of forms for a score or more of miles along the cliff base.
Volcanic features occur in abundance in the Plateau province. Some of the high plateaus in the north are capped with remnants of heavy lava flows of early eruption. A group of large volcanoes occurs on the limestone platform s6uth of the Grand Canyon, culminating in Mt San Francisco (12,794 ft.), a moderately dissected cone, and associated with many more recent smaller cones and freshlooking lava flows. Mt Taylor in western New Mexico is of similar age, but here dissection seems to have advanced farther, probably because of the weaker nature of the underlying rocks, with the result of removing the smaller cones and exposing many lava conduits or pipes in the form of volcanic necks or buttes. The Henry Mountains in south-western Utah are peculiar in owing their relief to the doming or blistering up of the plateau strata by the underground intrusion of large bodies or cisterns (laccolites) of lava, now more or less exposed by erosion.
The lava plains of the Columbia basin are among the most extensive volcanic outpourings in the world. They cover 200,000 sq. m. or more in south-eastern Washington, eastern Oregon and southwestern Idaho, and are known to be 4000 ft. deep in sonic river gorges. The lava completely buries the pre-existent land forms over most of its extent. The earlier supposition that these vast lava flows came chiefly from fissure eruptions has been made doubtful by the later discovery of flat-sloping volcanic cones from which much lava seems to have been poured out in a very liquid state. Some of the flows are still so young as to preserve their scoriaceous surface; here the shore-line of the lava contours evenly around the spurs and enters, bay-like, into the valleys of the enclosing mountains, occasionally isolating an outlying mass. Other~ parts of the lava flood are much older and have been more or less deformed and eroded. Thus the uplifted, dislocated and dissected lava sheets of the Yellowstone National Park in the Rocky Mountains on the east (about the headwaters of the Snake river) are associated with the older lavas,of the Columbian plains.
The Columbia river has entrenched itself in a canyon-like valley around the northern and Western side of the lava plains; Snake river has cut a deeper canyon farther south-east where the plains are higher and has disclosed the many lava sheets which build up the plains, occasionally revealing a buried mountain in which the superposed river has cut an even narrower canyon. One of the most remarkable features of this province is seen in the temporary course taken by the Columbia river across the plains, while its canyon was obstructed by Pleistocene glaciers that came from the Cascade Mountains on the north-west. The river followed the temporary course long enough to erode a deep gorge, known as Grande Coulee, along part of its length.
The lava plains are treeless and for the most part too dry for agriculture; but they support many cattle and horses. Along parts of their eastern border, where the rainfall is a little increased by the approach of the westerly winds to the Rocky Mountains, there is a belt of very deep, impalpably fine soil, supposed to be a dust deposit brought from the drier parts of the plains farther west; excellent crops of wheat are here raised.
The large province of the Basin ranges, an arid region throughout, even though it reaches the sea in southern California, involves some novel problems in its description. It is characterized The Basla by numerous disconnected mountain ranges trending north and south, from 30 to 100 in. in length, the higher V ranges reaching altitudes of 8000 or 10,000 ft., separated by broad, intermont desert plains or basins at altit,udes varying from sea-level (or a little less) in the south-west, to 4000 or 5000 ft. farther inland. Many of the intermont plainsthese chiefly in the north-appear to be heavily aggraded with mountain Waste; while others-these chiefly in the southare rock-floored and thinly veneered with alluvium. The origin of these forms is still in discussion; but the following interpretation is well supported. The ranges are primarily the result of faulting and uplifting of large blocks of the earths crust. The structure of the region previous to faulting was dependent on long antecedent processes of accumulation and deformation and the surface of the region then was dependent on the amount of erosion suffered in the prefaulting cycle. When, the region was broken into fault blocks and the blocks were uplifted and tilted, the back slope of each block was a part of the previously eroded surface and the face of the block was a surface of fracture; the present form of the higher blocks is more or less affected by erosion since faulting, while many of the lower blocks have been buried under the waste of the higher ones. In the north, where dislocations have invaded the field of the horizontal Columbian lavas, as in south-eastern Oregon and north-eastern California, the blocks are monoclinal in structure as well as in attitude; here the amount of dissection is relatively moderate, for some of the fault faces are described as ravined but not yet deeply dissected; hence these dislocations appear to be of recent date. In Western Utah and through most of Nevada many of the blocks exhibit deformed structures, involving folds and faults of relatively ancient (Jurassic) date; so ancient that the moun~ tains then formed by the folding were worn down to the lowland stage of old age before the block-faulting occurred. When this old-mountain lowland was broken into blocks and the blocks were tilted, their attitude, but not their structure, was monoclinal; and in this new attitude they have been so maturely re-dissected in the ne~v cycle of erosion upon which they have now entered as to have gained elaborately carved forms in which the initial form of the uplifted blocks can hardly be perceived; yet at least some of them still retain along one side the highly significant feature of a relatively simple base-line, transecting hard and soft structures alike, and thus indicating the faulted margin of a tilted block. Here the less uplifted blocks are now heavily aggraded with waste from the dissected ranges: the waste takes the form of huge alluvial fans, formed chiefly by occasional boulder-bearing floods from the mountains; each fan heads in a ravine at the mountain base, and becomes laterally confluent with adjacent fans as it stretches several miles forward with decreasing slope and increasing fineness of material.
In the southern part of the Basin Range province the ranges are well dissected and some of the intermont depressions have rock floors with gentle, centripetal slopes; hence it is suggested that the time since the last dislocation in this part of the province is relativel remote; that erosion in the current cycle has here advanced muc farther than in the central or northern parts of the province; and that, either by outwash to the sea or by exportation of wind-borne dust, the depressions-perhaps aggraded for a time in the earlier stages of the cyclehave now been so deeply worn down as to degrade the lower and weaker parts of the tilted blocks to an evenly sloping surface, leaving the higher and harder parts still in relief as residual ranges. If this be true, the southern district will furnish a good illustration of an advanced stage of the cycle of arid erosion, in which the exportation of waste from enclosed depressions by the wind has played an important part. In. such case the washing of the centripetal slopes of the depressions by occasional sheetfloods (widespreading sheets of turbid running water, supplied by heavy short-lived rains) has been efficient in keeping the rock floor at even grade toward a central basin, where the finest waste is collected while waiting to be removed by the winds.
Only a small part of the Basin Range province is drained to the sea. A few intermont areas in the north-west part of the province have outlet westward by Kla1nath river through the Cascade range and by Pitt river (upper part of the Sacramento) through the Sierra Nevada: a few basins in the south-east have outlet by the Rio Grande to the Gulf of Mexico; a much larger but still narrow medial area is drained south-westward by the Colorado to the head of the Gulf of California, where this large and very turbid river has formed an extensive delta, north of which the former head of the gulf is now cut off from the sea and laid bare by evaporation as a plain below sea-level. It is here that an irrigation project, involving the diversion of some of the river water to the low plain, led to disaster in 1904, when the flooded river washed away the canal gates at the intake and overflowed the plain, drowning the newly established farms, compelling a railway to shift its track, and forming a lake (Salton Sea) which would require years of evaporation to remove (see COLORADO RIvER). Many streams descend from the ravines only to wither away on the desert basin floors before uniting in a trunk river along the axis of a depression; others succeed in uniting in the winter season, when evaporation is much reduced, and then their trunk flows for a few score miles, only to disappear by sinking (evaporating) farther on. A few of the large streams may, when in flood, spr.ead out in a temporary shallow sheet qn a dead level of clay, or playa, in a basin centre, but the sheet of water vanishes in the warm season and the stream shrinks far up its course, the absolutely barren clay floor of the playa, impassable when wet, becomes firm enough for crossing when dry. One of the southwestern basins, with its floor below sea-level, has a plain of salt in its centre. A few of the basins are occupied by lakes without outlet, of which Great Salt Lake, in north-west Utah, is the largest. Several smaller lakes occur in the basins of western Nevada, next east of the Sierra Nevada. During Pleistocene times all these lacustrine basins were occupied by lakes of much greater depthand la~ger size; the outlines of the eastern (Lake Bonneville) and the western (Lake Lahontan) water bodies are well recorded by shore lines and deltas on the enclosing slopes, hundreds of feet above the present lake surfaces; the abandoned shore lines, as studied by G. K. Gilbert and I. C. Russell, have yielded evidence of past climatic changes second in importance only to those of the Pleistocene glaciated areas. The duration of the Pleistocene lakes was, however, brief as compared with the time since the dislocation of the faulted blocks, as is shown by the small dimensions of the lacustrine beaches compared to the great volume of the ravine-heading fans on which the beaches often lie.
Strong mountain ranges follow the trend of the Pacific coast, 150 or 200 m. inland. The Cascade Range enters from Canada, trending sotithward across the international boundary through ThePacifk Washington and Oregon to latitude 41; the Sierra Ranges. Nevada extends thence south-eastward through Cali fornia to latitude 35. The lower coast ranges, nearer the ocean, continue a little farther southward than the Sierra Nevada, before giving way to that part of the Basin Range province which reaches the Pacific in southernmost California.
The Cascade Range is in essence a maturely dissected highland, composed in part of upwarped Colombian lavas, in part of older rocks, and crowned with several dissected volcanoes, of which the chief are (beginning in the north) Mts Baker (Io,827 ft.), Rainier (14,363 ft.), Adams (12,470 ft.) and Hood (11,225 ft.); the first three in \Vashington, the last in northern Oregon- These bear snowfields and glaciers; while the dissected highlands, with ridges of very irregular arrangement, are everywhere sculptured in a fashion that strongly suggests the work of numerous local Pleistocene glaciers as an important supplement to preglacial erosion. Lake Chelan, long and narrow, deep set between spurless ridges with hanging lateral valleys, and evidently of glacial origin, ornaments one of the eastern valleys. The range is squarely transected by the Columbia river, which bears every appearance of antecedent origin:
the cascades in the river gorge are caused by a sub-recent landslide of great size from the mountain walls. Kiamath river, draining several lakes in the north-west part of the Basin Range province and traversing the Cascade Range to the Pacific, is apparently also an antecedent river.
The Cascade Mountains present a marked example of the effect of relief and aspect on rainfall; they rise across the path of the prevailing westerly winds not far inland from a great ocean; hence they receive an abundant rainfall (80 in. or more, annually) on the Westward or windward slope, and there they are heavily forested; but the rainfall is light on the eastward slope and the piedmont district is dry; hence the forests thin out on that side of the range and treeless lava plains follow next eastward.
The Sierra Nevada may be described, in a very general way, as a great mountain block, largely composed of granite and deformed metamorphosed rocks, reduced to moderate relief in an earlier (Cretaceous and Tertiary?) cycle of erosion, sub-recently elevated with a slant to the west, and in this position sub-maturely dissected. The region was by no means a peneplain before its slanting uplift; its surface then was hilly and in the south mountainous; in its central and still more in its northern part it was overspread with lavas which flowed westward along the broad open valleys from many vents in the eastern part: near the northern end of the range, eruptions have continued in the present cycle, forming many cones and young lava flows. The tilting of the mountain mass was presumably not a simple or a single movement; it was probably slow, for Pitt river (headwaters of the Sacramento) traverses the northern part of the range in antecedent fashion; the tilting involved the subdivision of the great block into smaller ones, in the northern half of the range at least; Lake Tahoe (altitude 6225 ft.) near the range crest is explained as occupyilig a depression between two block fragments; and farther north similar depressions now appear as aggraded highland meadows. The tilting of the great block resulted in presenting a strong slope to the east, facing the deserts of the Basin Range province and in large measure determining their aridity; and a long moderate slope to the west. The altitudes along the upraised edge of the block, or range crest, are approximately 5000 ft. in the north and 11,000 ft. in the south. The mountains in the southern part of the block, which had been reduced to subdued forms in the former cycle of erosion, were thus given a conspicuous height, forming the High Sierra, and greatly sharpened by revived erosion, normal and glacial. In this way Mt Whitney (14,502 ft.) came to be the highest summit in the United States (excluding Alaska). The displacement of the mountain block may still be in progress, for severe earthquakes have happened in the depression next east of the range; that of Owens Valley in 1870 was strong enough to have been very destructive had there been anything in the desert valley to destroy. In the new altitude of the mountain mass, its steep eastern face has been deeply carved with short canyons; and on the western slope an excellent beginning of dissection has been made in the erosion of many narrow valleys, whose greatest depth lies between their headwaters which still flow on the highland surface, and their mouths at the low western base of the range. The highlands and uplands between the chief valleys are but moderately dissected; many small side streams still flow on the highland, and descend by steeply incised gorges to the valleys of the larger rivers. Some of the chief valleys are not cut in the floors of the old valleys of the former cycle, because the rivers were displaced from their former courses by lava flows, which now stand up as table mountains. Glacial erosion has been potent in excavating great cirques and small rock-basins, especially among the higher southern surmounting summits, many of which have been thus somewhat reduced in, height while gaining an Alpine sharpness of form; some of the short and steep canyons in the eastern slope have been converted into typical glacial troughs, and huge moraines have been laid on the desert floor below them. Some of the western valleys have also in part of their length beeIi converted into U-shaped troughs; the famous Yosemite Vailey, eroded in massive granite, with side cliffs 1000 or 2000 ft. in height, and the smaller Hetch-I-Ietchy Valley not far away, are regarded by some observers as owing their peculiar forms to glacial modifications of normal preglacial valleys.
The western slope of the Sierra Nevada hears fine forests similar to those of the Cascade Range and of the Coast Range, but of more open growth, and with the redwood exchanged for groves of big trees (Sequoia gigantea) of which the tallest examples reach 325 ft. The higher summits in the south are above the tree line and expose great areas of bare rock: mountaineering is here a delightful summer recreation, with camps in the highland forests and ascents to the lofty peaks. Gold occurs in quartz veins traversing various formations (some as young as Jurassic), and also in gravels, which were for the most part deposited previous to the uplift of the Sierra block. Some of the gravels then occurred as piedmont deposits along the western border of the old mountains; these gravels are now more or less dissected by new-cut valleys. Other auriferous gravels are buried under the upland lava flows, and are now reached by tunnels driven in beneath the rim of the table mountains. The reputed discovery of traces of early man in the lava-covered gravels has not been authenticated.
The northernmost part of the coast ranges, in Washington, is often given independent rank as the Olympic Range (Mt Olympus, 8150 ft.); it is a picturesque mountain group, bearing snowfields and glaciers, and suggestive of the dome-like uplift of a previously worn-down mass; but it is now so maturely dissected as to make the suggested origin uncertain. Farther south, through Oregon and northern California, many members of the coast ranges resemble the Cascades and the Sierra in offering well-attested examples of the uplift of masses of disordered structure, that had been reduced to a tame surface by the erosion of an earlier cycle, and that are now again more or less dissected.
Several of the ranges ascend abruptly from the sea; their base is cut back in high cliffs; the Sierra Santa Lucia, south of San Francisco, is a range of this kind; its seaward slope is almost uninhabitable. Elsewhere moderate re-entrants between the ranges have a continuous beach, concave seaward; such re-entrants afford imperfect harbourage for vessels; Monterey Bay is the most pronounced example of this kind. On still other parts of the coast a recent small elevatory movement has exposed part of the former sea bottom in a narrow coastal plain, of which some typical harbourless examples are found in Oregon. Most of the recent movements appear to have been upward, for the coast presents few embayments such as would result from the depression and partial submergence of a disse~ted mountain range; but three important exceptions must be made to this rule.
In the north, the Strait of Juan de Fuca and the intricately branching waterways of Puget Sound between the Cascade and the Olympic ranges occupy trough-like depressions which were filled by extensive glaciers in Pleistocene times; and thus mark the beginning of the great stretch of forded coast which extends northward to Alaska. rhe waterways here afford excellent harbours. The second important embayment is the estuary of the Columbia river; but theoccurrence of shoals at the mouth decreases the use that might otherwise be made of the river by ocean-going vessels. More important is San Francisco Bay, situated about midway on the Pacific coast of the United States, the result of a moderate depression whereby a transverse valley, formerly followed by Sacramento river through the outermost of the Coast ranges, has been converted into a narrow straitthe Golden Gate and a wider intermont longitudinal valley has been flooded, forming the expansion of the inner bay.
The Coast Range is heavily forested in the north, where rainfall is abundant in all seasons; but its lower ranges and valleys have a scanty tree growth in the south, where the rainfall is very light: here grow redwoods (Sequoia semperzirens) and live oaks (Quercus agrifolia). The chief metalliferous deposits of the range are of mercury at New Almaden, not far south of San Francisco. The open valleys between the spaced ranges offer many tempting sites for settlement, but in the south irrigation is needed for cultivation.
The belt of ielative depression between the inner Pacific ranges and the Coast range is dhided by the fine volcano Mt Shasta (14,380 ft.) in northern California into unlike portions. To the north, the floor of the depression is for the most part above baselevel, and hence is dissected by open valleys, partly longitudinal, partly transverse, among hills of moderate relief. This district was originally for the most part forested, but is now coming to be cleared and farmed.
South of Mt Shasta, the Valley of California is an admirable example of an aggraded intermont depression, about 400 m. long and from 30 to 70 m. wide. The floor of this depression being below baselevel, it has necessarily come to be the seat of the mountain waste brought down by the many streams from the newly uplifted Sierra Nevada on the east and the coast ranges on the west; each stream forms an alluvial fan of very gentle slope; the fans all become laterally confluent, and incline very gently forward to meet in a nearly level axial belt, where the trunk riversthe Sacramento from the north and the San Joaquin from the south-east--wander in braided courses; their tendency to aggradation having been increased in the last half century by the gravels from gold washing; their waters entering San Francisco Bay. Kings river, rising in the high southern Sieria near I~It Whitney, has built its fan rather actively, and obstructed the discharge from the part of the valley next farther south, which has thus come to be overflowed by the shallow waters of Tulare Lake, of flat, reedy, uncertain borders. A little north of the centre of the valley rise the Marysville Buttes, the remains of a maturely dissected volcano (2128 ft). Elsewhere the floor of the valley is a featureless, treeless plain. (W. M. D.)
All the great systems of rock formations are represented in the United States, though close correlation with the systems of Europe is not always possible. The general geological column for the country is shown in the following table:
Eras of Time. Periods of Time.
Groups of Systems. Systems of Rocks.
Transition (Arapahoe and Denver formations).
~ Upper Cretaceous.
Mesozoic -. - ~ Comanchean (Lower Cretaceous). I Jurassic.
Coal Measures, or Pennsylvanian.
Subcarboniferous, or Mississippian.
Proterozoic, Widespread unconformity.
Widespread ii nconformity, Lower Huronian.
~Great Granitoid Series (intru sive in the main, Laurentian).
Archeozoic - -. Archean Great Schist Series (Mona, Kitchi, Keewatin, Quinnissec; Lower Huronian of some L authors).
Archeozoic (Archean) Group.The oldest group of rocks, called the Archean, was formerly looked upon, at least in a tentative way, as the original crtist of the earth or its downward extension, much altered by the processes of metamorphism. This view of its origin is now known not to be applicable to the Archean as a whole, since this system contains some metamorphosed sedimentary rocks. In other words, if there was such a thing as an original crust, which may be looked upon as an open question, the Archean, as now defined, does not appear to represent it. The meta-sedimentary rocks of the Archean include metamorphosed limestone, and schists which carry carbonaceous matter in the form of graphite. The marble and graphite, as well as some other indirect evidence of life less susceptible of brief statement, have been thought by many geologists sufficient to warrant the inference that life existed before the close of the era when the Archean rocks were formed. Hence the era of their formation is called the Archeozoic era.
Most of tie Archean rocks fall into one or the other of two great series, a schistose series and a granitoid series, the latter being in large part intrusive in the former. The rocks of the granitoid series appear as great masses in the schist series, and in some places form great protruding bosses. They were formerly regarded as older thaii the schists and were designated on this account primitive, fundamental, &c. They have also been called Laurenlian, a name which is still sometimes applied to them.
Nearly all known sorts of schist are represented in the schistose nart of the system. Most of them are the metamorphic products of igneous rocks, among which extrusive rocks, many of them pyroelastic, predominate. Metamorphosed sedimentary rocks are widely distributed in the schistose series, but they are distinctly subordinate to the meta-ignecius rocks, and they are so highly metamorphic that stratigraphic methods are not usually applicable to them. In some areas, indeed, it is diffictilt to say whether the schists are metasedimentary or meta-igneous. The likeness of the Archean of one part of the country to that of another is one of its striking features.
The Archean appears at the surface in many parts of the United States, and in still larger areas north of the national boundary. It appears in the cores of some of the western mountains, in some of the deep canyons of the west, as in the Grand Canyon of the Colorado in northern Arizona, and over considerable areas in northern Wiscpnsin and Minnesota, in New England and the piedmont plateau east of the Appalachian Mountains, and in a few other situations. Wherever it comes to the surface it comes up from beneath younger rocks which are, as a rule, less metamorphic. By means of deep borings it is known at many points where it does not appear at the surface, antI is believed to be universal beneath younger systems.
Prolerozoic (Algonkian) Systems.The Proterozoic group of rocks (called also Algonkian) includes all formations younger than the Archean and older than the Palaeozoic rocks. The term Archean was formerly proposed to include these rocks, as well as those now called Archean, btit the subdivision here recognized has come to be widely approved.
The Proterozoic formations have a wide distribution. They appear at the surface adjacent to most of the outcrops of the Archean, and in some other places. In many localities the two groups have not been separated. In some places this is because the regions where they occur have net been carefully studied since the subdivision into Archeozoic and Proterozoic was made, and in others because of the inherent difficulty of separation, as where the Proterozoic rocks are highly metamorphosed. On the whole, the Proterozoic rocks are predominantly sedimentary and subordinately igneous. Locally both the sedimentary and igneous parts of the group have been highly metamorphosed; but as a rule the alteration of the sedimentary portions has not gone so far that stratigraphic methods are inapplicable to them, though in some places detailed study is necessary to make out their structure.
The Proterozoic formations are unconformable on the Archean in most places where their relations are known. The unconformity between these groups is therefore widespread, probably more so than any later unconformity. Not only is it extensive in area, but the stratigraphic break is very great, as shown by (I) the excess of metamorphism of the lower group as compared with the upper, and (2) the amount of erosion suffered by the older group before the deposition of the younger. The first of these differences between the two systems is significant of the dynamic changes suffered by the Archean before the beginning of that part of the Proterozoic era represented by known formations. The extent of the unconformity is usually significant of the geographic changes of the interval unrecorded by known Proterozoic rocks.
The Proterozoic formations have been studied in detail in few great areas. One of these is about Lake Superior, where the formations have attracted attention on account of the abundant iron ore which they contain. Four major subdivisions or systems of the group have been recognized in this region, as shown in the preceding table. These systems are separated one from another by unconformitics in most places, and the lower systems, as a rule, have sufferetl a greater degree of metamorphism than the upper ones, though this is not to be looked upon as a hard and fast rule. The commoner sorts of rock in the several Huronian systems are quartzite and slate (ranging from shale to schist); bi~t limestone is not wanting, and igneous rocks, both intrusive and extrtisive, some metamorphic and some not, abound. Iron ore occurs in the sedimentary part of the Huronian, especially in Minnesota, Michigan, Wisconsin and parts of Canada. The ore is chiefly haematite, and has been developeci from antecedent ferruginous sedimentary deposits, through concentration and purification by ground water.
The lower part of the Keweenawan system consists of a great succession of lava flows, of prodigious thickness.- This portion of the system is overlain by thick beds of sedimentary rock, mostly conglomerate and sandstone, derived from the igneous rocks beneath. A few geologists regard the sedimentary rocks here classed as Keweenawan as Palaeozoic; but they have yielded no fossils, and are unconformable beneath the Upper Cambrian, which is the oldest sedimentary formation of the region which bears fossils. The aggregate thickness of the Proterozoic systems in the Lake Superior region is several miles, as usually computed, but there are obvious difficulties in determining the thickness of such great systems, especially when they are mtich metamorphosed. The copper of the Lake Superior region is in the Keweenawaii system, chiefly in its sedimentary and amygdaloidal parts.
The Proterozoic formations in other parts of the continent cannot be correlated in detail with those of the Lake Superior region. The number of systems is not everywhere the same, nor are they everywhere alike, and their definite correlation with one another is not possible now, and may never be. The Proterozoic formations have yielded a few fossils in several places, especially Montana and northern Arizona; but they are so imperfect, their numbers, whether of individuals or of species, are so small, and the localities where they occur so few, that they are of little service in correlation throughout the United States. The carbon-bearing shales, slates and schists, and the limestone, are indications that life was relatively abundant, even though but few fossils are preserved. ,Among the known fossils are vermes, crustacea and probably brachiopods and pteropods The character of the sediments of the Proterozoic is such as to show that mature weathering affected the older rocks before their material was worked over into the Proterozoic formations. This mature weathering, resulting in the relatively complete separation of the quartz from the kaolin, and both from the calcium carbonate and other basic materials, implies conditions of rock decay comparable to those of the present time.
In all but a few places where their relations are known, the Proterozoic rocks are unconformable beneath the Palaeozoic Where conformity exists the separation is made on the basis of fossils, it having been agreed that the oldest rocks carrying the Olenellus fauna are to be regarded as the base of the Cambrian system.
The Palaeozoic and later formations are usually less altered, 115 110.14~ I/o ~ i~c ~
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more accessible, and better known than the Proterozoic and Archeozoic, and will be taken up by systems.
Cambrian System.The lower part of the Cambrian system, characterized by the Olenellus fauna, is restricted to the borders of the continent, where it rests on the older rocks unconformably in most places. The middle part of the system, characterized by the Paradoxides fauna, is somewhat more widespread, resting on the lower part conformably, but overlapping it, especially in the south and west. The upper part of the system, carrying the Dicellocephalus fauna, is very much more extensive; it is indeed one of the most widespread series of rocks on the continent. The lower, middle and upper parts of the system all contain marine fossils. This being the case, the distribution of the several divisions indicates that progressive submergence of the United States was in progress during the period, and that most of the country was covered by the sea before its close.
- The system is composed chiefly of clastic rocks, and their composition and structure show that the water in which they were deposited was shallow. In the interior, the upper part of the system, the Potsdam sandstone, is generally arenaceous. It is well exposed in New York, Wisconsin, Missouri and elsewhere, about the outcrops of older rocks. The system is also exposed in many of the western mountains or about their borders, especially about those the cores of which are of Archean or Proterozoic rock.
The thickness of the system has been estimated at 10,009 to 12,000 ft. in eastern New York, and almost as much in the southern Appalachian Mountains (Georgia and Alabama); but its average thickness is much less. In Wisconsin, where the Upper Cambrian only is present, the thickness is about Iooo ft. The greater thickness in the east appears to be due in part to the fact that an extensive area of land, Appalachia. lay east of the site of the Appalachian Mountains throughout the Palaeozoic era, and quantities of sediment from it Were accumulated where these mountains were to arise later. The greatness of the thickness, as it has been measured, is also due in part to the oblique position in which the beds of sediment were originally deposited.
The Cambrian formations have not been notably metamorphosed, except in a few regions where dynamic metamorphism has been effective. The system is without any notable amount of igneous rock. As in other parts of the world, the system here contains abundant fossils, among which trilobites, brachiopods and worms are the most abundant. The range of forms, however, is great.
Ordovician System.The succeeding Ordovician (Lower Silurian) system of rocks is closely connected with the Cambrian, geographically, stratigraphically and faunally. Its distribution is much the same as that of the Upper Cambrian, with which it is conformable in many places. The Ordovician system contains much more 9~ S~ ~ 1~
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limestone, and therefore much less elastic rock, than the Cambrian, pointing to clearer seas in which life abounded. The succession of beds in New York has become a sort of standard with which the system in other parts of the United States has been compared. The succession of formations in that state is as follows Upper Ordovician (or J and Indiana).
Cincinnatian) Lorraine beds.
1 Utica shales.
Middle Ordovician (or I Trenton limestone.
Ordovician Mohawkian) -~ Black River limestone.
Lower Ordovician (or I Chazy limestone.
Canadian) -~ Beekmantown limestone.
The classification in the right-hand column of this table is not applicable in detail to regions remote from New York.
There is in some places an unconformity between the Richmond beds (or their equivalent) and underlying formations, and this unconformity, together with certain palaeontological considerations, has raised the question whether the uppermost part of the system, as outlined above, should not be classed as Silurian (Upper Silurian). Over the interior the strata are nearly horizontal, but in the mountain regions of the east and west, as well as in the mountains of Arkansas and Oklahoma, they are tilted and folded, and locally much metamorphosed. The outcrops of the system appear for the most part in close association with the outcrops of the Cambrian system, but the system appears in a few places where the Cambrian does not, as in southern Ohio and central Tennessee. The thickness of the system varies from point to point, being greatest in the Appalachian Mountains, and much less in the interior.
The oil and gas of Ohio and eastern Indiana come from the middle portion of the Ordovician system. So also do the lead and zinc of south-western Wisconsin and the adjacent parts of Iowa and Illinois. The lead of south-eastern Missouri conies from about the same horizon.
The fossils of the Ordovician system show that life made great progress during the, period, in numbers both of individuals and of species. The life, like that of the later Cambrian, was singularly cosmopolitan, being in contrast with the provincial character of the life of the earlier Cambrian and of the early (Upper) Silurian which followed. Beside the expansion of types which abounded in the Cambrian, vertebrate remains (fishes) are found in the Ordovician. So, also, are the first relics of insects. The departure of the Ordovician life from that of the Cambrian was perhaps most pronounced in the great development of the molluscs and crinoids (including cystoids), but corals were also abundant for the first time, and graptolites came into prominence.
Siluriaii System.The Silurian system is much less widely distributed than the Ordovician. This and other corroborative facts imply a widespread emergence of land at the close of the Ordovician period. As a result of this emergence the stratigraphic break between the Ordovician and the Silurian is one of the greatest in the whole Palaeozoic group.
The classification of the system in New York is as follows:
Cayugan (Neo- or J Rondout waterlime.
Upper Silurian) ~ Cobleskill limestone.
Silurian -. Niagaran (Meso- or J Lockport limestone.
Middle Silurian) Rochester shale.
- Clinton beds.
Oswegan (Palaeo-or 1~1e~na sandstone.
Lower Silurian) ~ Oneida conglomerate.
The lower part of this system is chiefly elastic, and is known only in the eastern part of the continent. The middle portion contains much limestone, generally known as the Niagara limestone, and is mtich more widespread than the lower, being found very generally over the eastern interior, as far west as the Mississippi and in places somewhat beyond. The Niagara limestone contains the oldest known coral reefs of the continent. They occur in eastern Wisconsin and at other points farther east and south, It is over this limestone that the Niagara falls in the world-famous cataract. One member of the middle division of the system (Clinton beds) contains much iron ore, especially in the Appalachian Mountain region. The ore is extensively worked at some points, as at Birmingham, Alabama. The upper part of the system is more restricted than the middle, and includes the salt-bearing series of New York, Ohio and Pennsylvania, with its peculiar fauna. It is difficult to see how salt could have originated in this region except under conditions very different climatically from those of the present time.
In the interior the thickness of the system is less than 1000 ft. in many places, but in and near the Appalachian Mountains its thickness is much greatermore than five times as great if the maximum thicknesses of all formations be made the basis of calculation. In the Great Plains and farther west the Silurian has little known representation. Either this part of the continent was largely land at this time, or the Silurian formations here have been worn away or remain undifferentiated. Rocks of Silurian age, however, are known at some points in Arizona, Nevada and southern California.
Corals, echinoderms, brachiopods and all groups of molluscs abounded. Graptolites had declined notably as compared with the Ordovician, and the trilobites passed their climax before the end of the period. Certain other remarkable crustacea, however, had made their appearance, especially in connection with the Salina series of the east.
There are numerous outliers of the Silurian north of the United States, even tip to the Arctic regions. These outliers have a common fauna, which is closely related to that of the interior of the United States. They give some clue to the amount of erosion which the system has suffered, and also afford a clue to the route by which the animals whose fossils are found in the United States entered this country., Thus, the Niagara fauna of the interior of the United States has striking resemblances to the mid-Silurian fatinasof Sweden and Great Britain. It seems probable, therefore, that marine animals found migratory conditions between these regions, probably by way of northern islands. The fauna of the Appalachian region is far less like that of Europe, and indicates but slight connection with the fauna of the interior. Both the earlier and the later parts of the Silurian period seem to have been times when physical conditions were such as to favor the development of provincial faunas, while during the more widespread submergence of the middle Silurian the fauna was more cosmopolitan.
Devonian System.The Devonian system appears in some parts of New England, throughout most of the Appalachian region, over much of the eastern interior from New York to the Missouri River, in Oklahoma, and perhaps in Texas. It is absent from the Great Plains, so far as now known, and is not generally present in the Rocky Mountains, though somewhat widespread between them and the western coast. As a whole, the system is more-widespread than the Silurian, though not so widespread as the Ordovician. As in the case of the Ordovician and the Silurian, the New York section has become a standard with which the system in other parts of the country is commonly compared. This section is as follows: ~Chautauquan-Chemung (including CatI skill).
Upper - IPortage beds.
Devonian Senecan.. -~ Genesee shale.
~Erian.. Hamilton shale.
I Marcellus shale.
1) ni Middle ~ ~Onondaga (Corniferous ,evo an. Devonian I Ulsterian. limestone)
I. 1 Schoharie grit. I,Esopus grit.
Oriskanian Oriskany beds.
Lower. 1 HelderbergianJ Becraft limestone.
Devonian New Scotland beds.
The formations most widely recognized are the Helderberg limestone, the Onondaga limestone and the Hamilton shale.
The Catskill sandstone, found chiefly in. the Catskill Mountain region of New York, is one of the distinctive formations of the system. It has some similarity to the Old Red Sandstone of Great Britain. In part, at least, it is equivalent in time of origin to the Chemung formation; but the latter is of marine origin, while the Catskill formation appears to be of terrestrial origin.
No other system of the United States brings out more clearly the value of palaeontology to palaeogeography. The faunas of the early Devonian seem to have entered what is now the interior of the United States from the mid-Atlantic coast. The Onondaga fauna which succeeded appears to have resulted from the commingling of the resident lower Devonian fauna with new emigrants from Europe by way of the Arctic regions. The Hamilton fauna which followed represents the admixture of the resident Onondaga fauna with new types which are thought to have come from South America, showing that faunal connections for marine life had been made between the interior of the United States and the lands south of the Caribbean Sea, a connection of which, before this time, there was no evidence. The late Devonian fauna of the interior represents the commingling of the Hamilton fauna of the eastern interior with new emigrants from the north-west, a union which was not effected until toward the close of the period.
Like the earlier Palaeozoic systems, the Devonian attains its greatest known thickness in the Appalachian Mountains, where sediments from the lands of pre-Cambrian rock to the east accumulated in quantity. Here clastic rocks predominate, while limestone is more abundant in the interior, If the maximum thicknesses of all Devonian formations be added together, the total for the system is as much as 15,000 ft.; but such a thickness is not found in any one pluce.
The Devonian system yields much oil and gas in western Pennsylvania, south-western New York, West Virginia and Ontario; and some of the Devonian beds in Tennessee yield phosphates of commercial value. The Hamilton formation yields much flagstone.
Among the more important features of the marine life of the period were (1) the great development of the molluscs, especially of cephalopods; (2) theabundanceoflargebrachiopods; (3) theaberrant tendencies of the trilobites; (4) the profusion of corals; and (5) the abundance, size and peculiar forms of the fishes. The life of the land waters was also noteworthy, especially for the great deployment of what may be called the crustacean-ostracodermo-vertebrate group. The crustacea were represented by eurypterids, the ostracoderms by numerous strange, vertebrate-like forms (Cephalaspis, Gyathaspis, Trematopsis, Bothriolepss, &c.), and the vertebrates by a great variety of fishes, The land life of the period is represented more fully among the fossils than that of any preceding period. Gymnosperms were the highest types of plants.
The Devonian system is not set off from theMississippian by any marked break. On the other hand, the one system merges into the other, so that the plane of separation is often indistinct.
Mississippian SystemThe Mississippian system was formerly regarded as a part of the Carboniferous, and was described under the name of Lower Carboniferous, or Subcarboniferous, without the rank of a system. This older classification, which has little support except that which is traditional, is still adhered to by many geologists; hut the fact seems to be that the system is set off from the Pennsylvanian (Upper Carboniferous) more sharply than the Cambrian is from the Ordoviciao, the Silurian from the Devonian, or the Devonian from the Mississippian.
The system is well developed in the Mississippi Basin, whence its name, Its formations are much more widespread than those of any other system since the Ordovician. They appear at the surface in great areas in the interior, in the south-west and about many of the western mountains. In many places in the west they rest on what appear to be Ordovician beds, but without unconformity. The explanation of the apparent conformity of the strata from the Cambrian to the Pennsylvanian in some parts of the west, with no fossils defining with certainty any horizon between the Ordovician and the Mississippian, is one of the open problems in the geology of the United States.
The subdivision of the system for various regions in the eastern part of the United States is as follows:
Mississippi River States. Ohio. Pennsylvania. M~
4. Kaskaskia or Chester 7.7. Maxville 3. St Louis 6. Logan 3. Mf 2. Osage or Augusta (in- 5.5. Black Hand 2. Mauch Chunk cluding the Bur- 4. Cuyahoga 2. Gr lington, Keokuk 3. Sunbury and \Varsaw) 2. Berea grit 1. Kinderhook or Chou- 1. Bedford I. Pocono I. P0
teau In the interior the Kinderhook series has a distribution similar to that of the Devonian; the Osage series is more widespread, pointing to progressive submergence; and the St Louis is still more extensive. This epoch, indeed, is the epoch of maximum submerg,ence during the period, and the maximum since the Ordovician. Uefore its close the sea of the Great Basin which had persisted since the Devonian was connected with the shallow sea which covered much of the interior of the United States. The fourth series, the Kaskaskia or Chester, is more restricted, and points to the coming emergence of a large part of the United States. In the Mississippi Basin the larger part of the system is of limestone, though there is some clastic mateiial in both its basal and its upper parts. In Ohio the system contains much clastic rock, and in Pennsylvania little else. The Mauch Chunk series (shale and sandstone) is now believed to be largely of terrestrial origin.
The system ranges in thickness from nearly 5000 ft. maximum in Pennsylvania to 1500 ft. in the vicinity of the Mississippi river. In ~Vest Virginia some 2000 ft. of limestone are assigned to this system. The zinc and lead of the Joplin district of Missouri are in the limestone of this system, and the corresponding limestone in some parts of Colorado, as at Leadville, is one of the horizons of rich ore.
The end of the period was marked by the widespread emergence of the continent, and parts of it were never again submerged, so far as is known. Certainly there is no younger marine formation of comparable extent in the continent. When deposition was renewed in the interior of the continent, the formations laid down were largely non-marine, and, over great areas, they rest upon the Mississippian unconformably.
From the conditions outlined it is readily inferred that the faunas of the system were cosmopolitan. All types of life to which shallow, clear sea-water was congenial appear to have abounded in the interior. It was perhaps at this time that the crinoids, as a class, reached their climax, and most forms of lime-carbonate-secreting life seem to have thriven. Where the seas were less clear, as in Ohio, the conditions are reflected in the character of the fossils. Marine fishes had made great progress before the close of the period. Amphibia appeared before its close, and plant life was abundant and varied, though the types were not greatly in advance of those of the Devonian. The time of stich widespread submergence was hardly the time for the great development of land vegetation.
Pennsylvanian SystemThe Pennsylvanian or Upper Carboniferous system overlics the Mississippian unconformably over a large part of the United States. In the eastern half of the country the system consists of shales and sandstones chiefly, btit there is some limestone, and coal enough to be of great importance economically, though it makes but a small part of the system quantitatively. The larger part of the system in this part of the country is not of marine origin; yet the sea had access to parts of the interior more than once, as shown by the marine fossils in some of the beds. The dominantly terrestrial formations of the eastern half of the country are in contrast with the marine formations of the west. The line separating the two phases of the system is a little east of the 1 ooth meridian. West of the Mississippi the Coal Measures are subdivided into two series, the Des Moines below and the Missouri above. In the eastern part of the country (Pennsylvania, Ohio, &c.) the system is divided into four principal parts:
~ 4. Monongahela formation (or series)Upper Productive Coal Measures.
J 3 Conemaugh formation (or series)Lower Pennsylvanian. - Barren Coal Measures.
2. Allegheny formation (or series)Lower Prodtictive Coal Measures.
1. Pottsville formation (or series).
The Pottsville formation is chiefly clastic, and corresponds roughly to the Millstone Grit of England. The Allegheny and Monongahela series contain most of the coal, though it is not wanting in the other subdivisions of the system. Productive coal beds are found in five principal fields. These are (1) the Anthracite field in eastern Pennsylvania, nearly 500 sq. m. in extent; (2) the Appalachian field, having an area of about 71,000 sq. m. (75% being productive), and extending from Pennsylvania to Alabama; (3) the northern interior field, covering an area of about 11,000 sq. m. in southern Michigan; (4) the eastern interior field in Indiana, Illinois and Kentucky, with an area of about 58,000 sq. m. (55% being productive); and (5) the western interior and southwestern field, some 94,000 sq. m. in extent, reaching from -~ Iowa on the north to Texas on the south. There I d is also a coalfield in Nova Scotia and New Brunswick, bryan. about 18,000 sq. os. in extent. Some of the well-known beds of coal are known to be continuous for several h Ch k thousands of square miles.
uc un Unlike the older systems of the Palaeozoic, the enbrier Pennsylvanian system has not its maximum thickness - in the Appalachian Mountains, but in Arkansas, in a region which was probably adjacent to high lands at that time. These lands perhaps lay in the present - position of the Ouachita Mountains.
______ The close of the Pennsylvanian period was marked by the beginning of profound changes, changes in geography and climate, and therefore changes in the amount and habitat of life, and in the sites of erosion and sedimentation. One of the great changes of this time was the beginning of the development of the Appalachian Mountain system. The site of these mountains had been, for the most part, an area of deposition throughout the Palaeozoic era, and the body of sediments which had gathered here at the western base of Appalachia, by the close of the Pennsylvanian period, was very great. At this time these sediments, together with some of Appalachia itself, began to be folded up into the Appalachian Mountains. These mountains have since been worn down, so that, in spite of their subsequent periods of growth, their height is not great.
The chief interest of the palaeontology of this system is in the plants, which were very like those of the Coal Measures of other parts of the earth and showed a high development ,of forms that are now degenerate. Among land animals the amphibia had great development at this time. So also had insects and some other forms, of land life.
Permian Period.The Permian system appears in smaller areas in the United States than any other Palaeozoic system. The Upper Barren Coal Measures of some parts of the east (Ohio, Pennsylvania, &c.) are now classed as Permian on the basis of their fossil plants. They represent but a part of the Permian period, and are commonly described under the name of the Dunkard series.
The system has much more considerable development west of the Mississippi than east of it, especially in Texas, Kansas, Nebraska and beyond. Some of the Permian beds of this region are marine, while others are of terrestrial origin. In this part of the country the Permian beds are largely red sandstone, often saliferous and gypsiferous. They are distinguished with difficulty from the succeeding Triassic, for the beds have very few fossils. The system has its maximum known thickness in Texas, where it is said to be 7000 ft. in maximum thickness. West of the Rocky Mountainf the Permian has not been very generally separated from overlying and underlying formations, though it has been differentiated in a few places, as in south-western Colorado and in some parts of Arizona. Perhaps the most remarkable feature of the palaeontology of the system is its paucity of fossils, especially in those parts of the system, such as the Red Beds, which are of terrestrial origin.
In the United States no direct evidence has been found of the low tensperaturewhich brought about glaciation in many other parts of the earth during this period. Salt and gypsum deposits, and other features of the Permian beds, together with the fewness of fossils, indicate that the climate of the Permian was notably arid in many regions.
Triassic SystemThis system has but limited representation in the eastern part of the United States, being known only east of the Appalachian Mountains in an area which was land throughout most of the Palaeozoic era, hut which was deformed when the eastern mountains were developed at the close of the Palaeozoic. In the troughs formed in its surface during this time of deformation, sediments of great thickness accumulated during the Triassic period. These sediments are now mostly in the form of red sandstone and shale, with conglomerate, black shale and coal in some places. These rocks do not represent the whole of the period. They are often known as the Newark series, and seem to be chiefly, if not wholly, of terrestrial origin. The sedimentary rocks are affected by many dikes and sheets of igneous rock, some of the latter being extrusive and some intrusive. The strata are now tilted and much faulted, though but little folded. In the western plains and in the western mountains the Triassic is not clearly separated from the Permian in most places. So far as the system is differentiated, it is a part of the Red Beds of that region. The tendency of recent years has been to refer more and more of these beds to the Permian. The Triassic system is well developed on the Pacific coast, where its strata are of marine origin, and they extend inland to the Great Basin region.
The climate of the period, at least in its earlier part, seems to have been arid like that of the Permian, as indicated both by the paucity of fossils and by the character of the sediments. The salt and gypsum constitute a positive argument for aridity. The character of some of the conglomerate of the Newark series of the east, and the widespread redness of the beds, so far as it is original, also point to aridity.
As in other parts of the earth, the Triassic was the age of gymnosperms, which were represented by diverse types. Reptiles were the dominant form of animals, and land reptiles (dinosaurs) gained over their aquatic allies.
Jurassic SystemThis system is not known with certainty in the eastern half of the United States, though there are some beds on the mid-Atlantic coast, along the inland border of the coastal plain, which have been thought by some, on the basis of their reptilian fossils, to be Jurassic. The lower and middle parts of the system are but doubtfully represented in the western interior. If present, they form a part of the Red Beds of that region. On the Pacific coast marine Jurassic beds reach in from the Pacific to about the same distance as the Triassic system. The Upper Jurassic formations are much more widely distributed. During the later part of the period the sea found entrance at some point north of the United States to a great area in the western part of the continent, developing a bay which extended far down into the United States from Canada. In this great bay formations of marine origin were laid down. At the same time marine sedimentation was continued on the Pacific coast, but the faunas of the west coast and the interior bay are notably unlike, the latter being more like that of the coast north of the United States. This is the reason for the belief that the bay which extended into the United States had its connection with the sea north of the United States.
The Jurassic faunas of the United States were akin to those of other continents. The great development of reptiles and cephalopods was among the notable features. At the close of the period there were considerable deformations in the west. The first notable folding of the Sierras that has been definitely determined dates from this time, and many other mountains of the west were begun or rejuvenated. The close of the period, too, saw the exclusion of the sea from the Pacific coast east of the Sierras, and the disappearance, so far as the United States is concerned, of the great north-western bay of the late Jurassic. Before the close of the period, the aridity which had obtained during the Permian, and at least a part of the Triassic, seems to have disappeared.
Comanchean System.This system was formerly classed as the lower part of the Cretaceous, but there are strong reasons for regarding it as a separate system. Its distribution is very different from that of the Upper Cretaceous, and there is a great and widespread unconformity between them. The faunas, too, are very unlike. The Comanchean formations are found (I) on the inland border of the coastal plain of the Atlantic (Potomac series) and Gulf coasts (Tuscaloosa series at the east and Comanchean at the west); (2) along the western margin of the Great Plains and in the adjacent mountains; and (3) along the Pacific coast west of the Sierras. In the first two of these positions, the formations show by their fossils that they are of terrestrial origin in some places, and partly of terrestrial and partly of marine origin in others. In the coastal plain the Comanchean beds are generally not cemented, but consist of gravel, sand and clay, occupying the nearly horizontal position in which they were originally deposited. Much plastic clay and sand are derived from them. In Texas, whence the name Comanchean comes, and where different parts of the system are of diverse origins, there is some limestone. This sort of rock increases in importance southward and has great development in Mexico. In the western interior there is difference of opinion as to whether certain beds rich in reptilian remains (the Morrison, Atlantosaurus, Como, &c.) should be regarded as Jurassic or Comanchean. On the western coast the term Shastan is sometimes applied to Lower Cretaceous. In the United States, marine Shastan beds are restricted to the area west of the Sierras, but they here have great thickness.
Widespread changes at the end of the period exposed the areas where deposition has been in progress during the period to erosion, and the (Upper) Cretaceous formations rest upon the Comanchean unconformably in most parts of the country. The Comanchean system contains the oldest known remains of netted-veined leaved plants, which mark a great advance in the vegetable world. Reptiles were numerous and of great size. They were the largest type of life, both on land and in the sea.
Cretaceous System.This system is much more extensively developed in the United States than any other Mesozoic system. It is found (1) on the Atlantic coastal plain, where it laps up on the Comanchean, or over it to older formations beyond its inland margin; (2) on the coastal plain of the Gulf region in similar relations; (3) over the western plains; (4) in the western mountains; and (5) along the Pacific coast. Unlike the Cornanchean, the larger part of the Cretaceous system is of marine origin. The distribution of the beds of marine origin shows that the sea crept upon the eastern and southern borders of the continent auring the period, covered the western plains, and formed a great mediterranean sea between the eastern and western lands of the continent, connecting the Gulf of Mexico on the south and the Arctic Ocean on the north. This widespread submergence, followed by the deposition of marine sediments on the eroded surface of Comanchean and older rocks, is the physical reason for the separation of the system from the Comanchean. This reason is reinforced by palaeontological considerations.
Both on the Atlantic and over the western plains, the system is divided into four principal subdivisions:
Atlantic Coast. Western Plains.
4. Manasquan formation. 4. Laramie.
I. Matawan formation. 2. Colorado: Niobrara; Benton.
The most distinctive feature of the Cretaceous of the Atlantic coastal plain is its large content of greensand marl (glauconite). The formations are mostly incoherent, and have nearly their original position. In the eastern Gulf states there is more calcareous material, represented by limestone or chalk, In the Texan region and farther north the limestone becomes still more important. In the western plains, the first and last principal subdivisions of the system (Dakota and I,aramie) are almost wholly non-marine. The Dakota formation is largely sandstone, which gives rise to hogbacks where it has been tilted, indurated and exposed to erosion along the eastern base of the Rocky Mountains. The Colorado series contains much limestone, some of which is in the form of chalk. This is par excellence the chalk formation of the United States. That the chalk was deposited in shallow, clear seas is indicated both by the character of the fossils other than foraminifera and by the relation of the chalk to the elastic portions of the series. The Montana series, most of which is marine, was deposited in water deeper than that of the Colorado epoch, though the series is less widespread than the preceding. The Laramie is the great coalbearing series of the west, and corresponds in its general physical make-up and in its mode of origin to the Coal Measures of the east. The coal-bearing lands of the Laramie have been estimated at not less than 100,000 sq. m. On the Pacific coast the Cretaceous formations are sometimes grouped together under the name of Chico. The distribution of the Chico formations is similar to that of the Comanchean system in this region.
The Cretaceous system is thick. If maximum thicknesses of its several parts in different localities, as usually measured, are added together, the total would approach or reach 25,000 ft.; but the strata of any one region have scarcely more than half this thickness, and the average is much less.
The close of the period was marked by very profound changes which may be classed under three general headings: (1) the emergence of great areas which had been submerged until the closing stages of the period; (2) the beginning of the development of most of the great mountains of the west; (3) the inauguration of a protracted period of igneous activity, stimulated, no doubt, by the crustal and deeper-seated movements of the time. These great changes in the relation of land and water, and in topography, led to correspondingly great changes in life, and the combination marks the transition from the Mesozoic to the Cainozoic era.
Tertiary Systems.The formations of the sevefl Tertiary peripds have many points of similarity, but in some respects they are sharply differentiated one from another. They consist, in most parts of the country, of unconsolidated sediments, consisting of gravel, sand, clay, &c., together with large quantities of tuff, volcanic agglomerate, &c. Some of the sedimentary formations are of marine, some of brackish water, and some of terrestrial origin. In the western part of the country there are, in addition, very extensive flows of lava covering in the aggregate some 200,000 sq. m. Terrestrial sedimentation was, indeed, a great feature of the Tertiary. This was the result of several conditions, among them the recent development, through warping and faulting and volcanic extrusion, of high lands with more or less considerable slopes. From these high lands sediments were borne down to lodge on the low lands adjacent. The sites of deposition varied as the period progressed, for the warping and faulting of the surface, the igneous extrusions, and the deposition of sediments obliterated old basins and brought new ones into existence. The marine Tertiary formations are confined to the borders of the continent, appearing along the Atlantic, Gulf and Pacific coasts. The brackish water formations occur in some parts of the same general areas, while the terrestrial formations are found in and about the western mountains. As in other parts of the world, the chiefest palaeontological interest of the Tertiary attaches to the mammalian fossils.
The Eocene beds are unconformable, generally, upon the Cretaceous, and unconformable beneath the Miocene. On the Atlantic coast they are nearly horizontal, but dip gently seaward. E~eene On this coast they are nowhere more than a few system. hundred feet thick. In the Gulf region the system is more fully represented, and attains a greater thicknessI7oo ft. at least. In the Gulf region the Eocene system contains not a little non-marine material. Thus the lower Eocene has some lignite in the eastern Gulf region, while in Teias lignite and saliferous and gypsiferous sediments are found, though most of the system is marine and of shallow water origin. The Eocene of the western Gulf region is continued nor,h as far as Arkansas. The classification of the Eocene (and Oligocene) formations in the Gulf region, especially east of the Mississippi, is as follows:
4. Jacksonian Upper Eocene.
3. Claibornian Middle Eocene.
2. Chickasawan ?~ Lower Eocene.
1. i\Iidwayan The Jacksonian is sometimes regarded as Oligocene. This classification is based almost wholly on the fossils, for there seems to be little physical reason for the differentiation of the Oligocene anywhere on the continent.
On the Pacific coast the marine Eocene lies west of the Sierras, and between it and the Cretaceous there is a general, and often a great, unconformity. The system has been reported to have a thickness of more than 7000 ft. in some places, and locally (e.g. the Pescadero formation) it is highly metamorphic. The Eocene of southern California carries gypsum enough to be of commercial value. It is also the source of much oil. The system is wanting in northern California and southern Oregon, but appears again farther north, and has great development in Oregon, where its thickness has been estimated at more than 10,000 ft. As in other comparable cases, this figure does not make allowance for the oblique attitude in which the sediments were deposited, and should not be construed to mean the vertical thickness of the system.
In \Vashington the Eocene is represented by the Puget series of brackish water beds, with an estimated thickness exceeding that of the marine formations of Oregon. Workable coal beds are distributed through 3000 ft. of this series. The amount of the coal is very great, though the coal is soft.
Terrestrial Eocene formationseolian, fluvial, pluvial and lacustrineare widespread in the western part of the United States, both in and about the mountains. By means of the fossils, several more or less distinct stages of deposition have been recognized. Named in chronological order, these are:
I. The Fort Union stage, when the deposition was widespread about the eastern base of the northern part of the Rocky Mountains, and at some points in Colorado (Telluride formation) and New Mexico (Puerco beds), where volcanic ejecta entered largely into the formation. The Fort Union stage is closely associated with the Laramie, and their separation has not been fully effected.
2. The Wasatch stage, when deposition was in progress over much of Utah and western Colorado, parts of Wyoming, and elsewhere.
3. The Bridger stage, when deposition was in progress in the -\Vind River basin, north of the mountain of that name, and in the basin of Green river.
~. The Uinta stage, when the region south of the mountains of that name, in Utah and Colorado, was the site of great deposition.
More or less isolated deposits of some or all of these stages are found at numerous points in the western mountain region. The present height of the deposits, in some places as much as 10,000 ftgives some suggestion of the changes in topography which have taken place since the early Tertiary. The thickness of the system in the west is great, the formations of each of the several stages mentioned above running into thousands of feet, as thicknesses are commonly measured.
The Miocene system, generally speaking, has a distribution similar to that of the Eocene. The principal formation of the Mi Atlantic coastal plain is the Chesapeake formation, ~ ~ largely of sand. In Florida the system contains Y calcium phosphate of commercial value. The Miocene of the Atlantic and Gulf regions nowhere attains great thickness. The oil of Texas and Louisiana is from the Miocene (or possibly Oligocene) dolomite. On the Pacific coast the system has greater development. It contains much volcanic material, and great bodies of siliceous shale, locally estimated at 4000 ft. thick and said to be made up largely of the secretions of organisms. Such thicknesses of such material go far to modify the former opinion that the Tertiary periods were short. The Miocene of California is oilproducing. The terrestrial Miocene formations of the western part of the country are similar in kind, and, in a general way, in distribution, to the Eocene of the same region. The amount of volcanic material, consisting of both pyroclastic material and lava flows, is great.
At the close of the Miocene, deformative movements were very widespread in the Rocky Mountains and between the principal development of the Coast ranges of California and Oregon, and mountain-making movements, new or renewed, were somewhat general in the west. At the close of the period the topography of the western part of the country must have been comparable to that of the present time. This, however, is not to be interpreted to mean that it has remained unmodified, or but slightly modified since that time. Subsequent erosion has changed the details of topography on an extensive scale, and subsequent deformative movements have renewed large topographic features where erosion had destroyed those developed by the close of the Miocene. But in spite of these great changes since the Miocene, the great outlines of the topography of the present were probably marked out by the close of that period. Volcanic activity and faulting on a large scale attended the deforijiation of the closing stages of the Miocene.
The Pliocene system stands in much the same stratigraphic relation to the Miocene as the Miocene does to the Eocene. The marine Pliocene has but trifling development on the Atlantic Piior~ne coast north of Florida, and somewhat more extensive System. development in the Gulf region. The marine Pliocene of the continent has its greatest development in California (the Merced series, peninsula of San Francisco), where it is assigned a maximum thickness of nearly 6000 ft., and possibly as much as 13,000 ft. This wide range is open to doubt as to the correlation of some of the beds involved. Thicknesses of several thousand feet are recorded at other points in California and elsewhere along the coast farther north. Marine Pliocene beds are reported to have an altitude of as much as 5000 ft. in Alaska. The position of these beds is significant of the amount of change which has taken place in the west since the Pliocene period. The non-marine formations of the Pliocene are its most characteristic feature. They are widely distributed in the western mountains and ,on the Great Plains. In origin and character, and to some extent in distribution, they are comparable with the Eocene and Miocene formations of the same region, and still more closely comparable with deposits now making. In addition to these non-marine formations of the west, there is the widespread Lafayette formation, which covers niuch of the Atlantic and Gulf coastal plain, reaching far to the north from the western Gulf regio,1, and having uncertain limits, so far as now worked out, in various directions. The Lafayette formation has been the occasion of much difference of opinion, but is by many held to be a non-marine formation, made up of gravels, sands and clays, accumulated on land, chiefly through the agency of rain and rivers. Its deposition seems to have followed a time of deformation which resulted in an increase of altitude in the Appalachian Mountains, and in an accentuation of the contrast between the highlands and the adjacent plains. Under these conditions sediments from the high lands were washed out and distributed widely over the plains, giving rise to a thin but widespread formation of ill-assorted sediment, without marine fossils, and, for the most part, without fossils of any kind, and resting unconformably on Cretaceous, Eocene and Miocene formations. To the seaward the non-marine phase of the formation doubtless grades into a marine phase along the shore of that time, but the position of this shore has not been defined. The marine-part of the Lafayette is probably covered by sediments of later age.
In earlier literature the Lafayette formation was described under the name of Orange Sand, and was at one time thought to be the southern equivalent of the glacial drift. This, however, is now known not to be the case, as remnants of the formation, isolated by erosion, lie under the old glacial drift in Illinois, and perhaps elsewhere. It seems probable that the Lafayette formation of the Gulf coastal plain is continuous northward and westward with gravel deposits on the Great Plains, washed out from the Rocky Mountains to the west. The careful study of these fluvial formations is likely to throw much light on the history of the deformative movements and changes in topography in the United States during the late stages of geological history.
Deformative movements of the minor sort seem to have been in progress somewhat generally during the Tertiary periods, especially in the western part of the country, but those at the close of the Pliocene seem to have exceeded greatly those of the earlier stages. They resulted in increased height of land, especially in the west, and therefore in increased erosion. This epoch of relative uplift and active erosion is sometimes called the Sierran or Ozarkian epoch. The details of the topography of the western mountains are largel of post-Pliocene development. The summits of some of the big mountains, such as the Cascades, appear to be remnants of a peneplain developed in post-Miocene time. If so, the mountains themselves must be looked upon as essentially post-Pliocene. Deformative movements resulting in close folding were not common at this time, but such movements affected some of the coast ranges of California. This epoch of great deformation and warping marks the transition from the Tertiary to the Quaternary.
Quaternary Formations.The best-known formations of the Quaternary period are those deposited by the continental glaciers which were the distinguishing feature of the period ~
and by the waters derived from them. The glacial ac drift covers something like half of the continent, though much less than half of the United States. Besides the drift of the icesheets, there is much drift in the western mountains, deposited by local glaciers. Such glaciers existed in all the high mountains of the west, even down to New Mexico and Arizona.
The number of glacial epochs now recognized is five, trot eounting minor episodes. Four defined zones of interglacial deposits are detected, all of which are thought to represent great recessions of the ice, or perhaps its entire disappearance. The climate of some of the interglacial epochs was at least as warm as that of the present time in the same regions. The glacial epochs which have been differentiated are the following, numbered in chronological order:
(5) Wisconsin, (4) Iowan, (3) Illinoian, (2) Kansan, (I) SubAftonian, or Jerseyan. Of these, the Kansan ice-sheet was the most extensive, and the later ones constitute a diminishing series.
Essentially all phases of glacial and aqueo-glacial drift are represented. The principal terminal moraines are associated with the ice of the Wisconsin epoch. Terminal moraines at the border of the Illinoian drift are generally feeble, though widely recognizable, and such moraines at the margin of the Iowan and Kansan drift sheets are generally wanting. The edge of the oldest drift sheet is buried by younger sheets of drift in most places.
Loess is widespread in the Mississippi River basin, especially along the larger streams which flowed from the ice. Most of the bess is now generally believed to have been deposited by the wind. The larger part of it seems to date from the closing stages of the Iowan epoch, but bess appears to have come into existence after other glacial epochs as well. Most of the fossils of the bess are shells of terrestrial gastropods, but bones of land mammals are also found in not a few places. Some of the bess is thought to have been derived by the wind from the surface of the drift soon after the retreat of the ice, before vegetation got a foothold upon the new-made deposit; but a large part of the bess, especially that associated with the main valleys, appears to have been blown up on to the bluffs of the valleys from the flood plains below. As might be expected under these conditions, it ranges from fine sand to silt which approaches clay in texture. Its coarser phases are closely associated with dunes in many places, and locally the bess makes a considerable part of the dune material.
Much interest attaches to estimates of time based on data afforded by the consequences of glaciation. These estimates are far apart, and must be regarded as very uncertain, so far as actual numbers are concerned. The most definite are connected with estimates of the time since the last glacial epoch, and are calculated from the amount and rate of recession of certain falls, notably those of the Niagara and Mississippi (St Anthony Falls) rivers. The estimate of the time between the first and last glacial epochs is based on changes which the earlier drift has undergone as compared with those which the younger drift has undergone. Some of the estimates make the lapse of time since the first glacial epoch more than a million years, while others make it no more than one-third as long. The time since the last glacial epoch is but a fraction of the time since the first probably no more than a fifteenth or a twentieth.
Outside the region affected by glaciation, deposits by wind, rain, rivers, &c., have been building up the land, and sedimentation has N ~ been in progress in lakes and about coasts. The nontO ~ glacial deposits are much like the Tertiary in kind and gaca. distribution, except that marine beds have little representation on the land. On the coastal plain there is the Columbia series of gravels, sands and barns, made up of several members. Its distribution is similar to that of the Lafayette, though the Columbia series is, for the most part, confined to lower levels. Some of its several members are definitely correlated in time with some of the glacial epochs. The series is widespread over the lower part of the coastal plain. In the west the Quaternary deposits are not, in all cases, sharply separated from the late Tertiary, but the deposits of glacial drift, referable to two or more glacial epochs, are readily differentiated from the Tertiary; so, also, are certain lacustrine deposits, such as those of the extinct lakes Bonneville and Lahontan. On the Pacific coast marine Quaternary formations occur up to elevations of a few scores of feet, at least, above the sea.
Igneous rocks, whether lava flows or pyroclastic ejections, are less important in the Quaternary than in the Tertiary, though volcanic activity is known to have continued into the Quaternary. The Quaternary beds of lakes Bonneville and Lahontan have been faulted in a small way since they were deposited, and the old shore lines of these lakes have been deformed to the extent of hundreds of feet. So also have the shorelines of the Great Lakes, which came into existence at the close of the glacial period.
Much has been written and more said concerning the existence of man in the United States before the last glacial epoch. The present state of evidence, however, seems to afford no warrant for the conclusion that man existed in the United States before the end of the glacial period. Whatever theoretical reasons there may be for assuming his earlier existence, they must be held as warranting no more than a presumptive conclusion, which up to the present time lacks confirmation by certain evidence.
The following sections from selected parts of the country give some idea of the succession of beds in various type regions. The thicknesses, especially where the formations are metamorphosed, are uncertain.
WEST CENTRAL MASSACHUSETTS
Chicopee shale 200 ft. (?)
Granby tuff 580,,
Blackrock diabase (cones and dikes) -
Longmeadow sandstone 1000,,
Sugarboaf arkose 4660
Mount Toby conglomerate.
Beroardston series 2950 ft.
Leyden argillite 300 ft.
Conway schist Amherst schist - ~.-5ooo (~)
Brinfield fibrolite-schist J
Goshen schist 2000 ,, (?)
Hawley schist 2000 ft. (?)
Savoy schist 5000 ,, ?)
Chester amphibolite 3000 ,, (?)
Rowe schist 4000 ,, (?)
Hoosic schist 1500 ,, (?)
Becket gneiss 2000 ft.(?)
Washington gneiss 2000 ft.(?)
(Base not exposed.)
The above section is fairly representative for considerable parts of New England.
WEST VIRGINIA, &C.
(Top of system removed by erosion.)
Braxton formation 700 ft.
Upshur sandstone 300 500
Pugh formation 300 450,,
Pickens sandstone 400 500,,
Greenbrier limestone 350 400
Pocono sandstone 70 90,,
Jennings formation 3000-3800
Romney shale 1000f 300
Monterey sandstone 50 200 ft.
Lewiston limestone 5501050 ft.
Rockwood formation 100 800
Cacapon sandstone 100 630,,
Tuscarora quartzite 30 300
Junjata formation 2051250
Martinsburg shale 8ooi8oo ft.
Middle and Upper Cambrian.
Shenandoah limestone 2400 ft.
(Base not exposed.)
This section is fairly representative for the Appalachian Mountain tract, though the Cambrian is often more fully represented.
Dunkard formation C. 25 ft.
Monongahela formation 200 250 ft.
Conemaugh formation 400 500
Alleghany formation 165 300,,
Pottsville conglomerate 250
Maxville limestone C. 25 ft.
Waverley series Logan group 100 150 ft.
Black Hand conglomerate, 50 500
Cuyahoga shale 250 300
Sunbury shale 5 30,,
Berea grit 5_ 175
Bedford shale 50 150 ,,
Ohio shale 3002600 ft.
Olentangy shale 20 35
Delaware limestone 30 40
Columbus limestone 110 ,,
Monroe formation 50 600 ft.
Niagara group 150 350
Clinton limestone, 10 50 ,,
Medina shales (?) - 50 150
Saluda beds 20* ft.
Richmond formation 300 *
Lorraine formation 300*
Eden (Utica) shale 250
Trenton limestone 130
Benton formation 0 150 ft.
Dakota formation 50 100,,
Missouri formation 1500 It.
Des Moines formation 250 400
St Louis limestone 100 ft.
Osage (Augusta) formation 200 300,,
Kinderhook formation 150 200,,
Lime Creek formation 80 ft.
State Quarry beds 20 40
Sweetland Creek shales 20 40
Cedar Valley limestone 250 300 ft.
\Vapsipinicon formation (Independence, Fayette, Davenport) 100 150
Anamosa limestone 50 75 ft.
Le Claire limestone 50
Delaware stage 200,,
Maquoketa shales 175 ft.
Galena-Trenton limestone 290 ft.
St Peters sandstone 100,, Oneota formation (includes Shakopee, New Richmond and Oneota proper). .. 300,, Cambrian.
St Croix sandstone (~ Potsdam)... 1000 ft.
Sioux quartzite (?)
This section is fairly representative for much of the central Mississippi Basin.
(Summit removed by erosion.)
Seminole conglomerate 50 ft.
Holdenville shale 260
Wewaka formation 700
Wetumka shale 120
Calvin sandstone 145 240
Senora formation 140 485
Stuart shale 90 280
Thurman sandstone 80 260,,
Boggy shale 2000-2600
Savannah sandstone 7501100
McAlester shale 1150-1500
Hartshorne sandstone 150 200,,
Atoka formation (Chickahoc chert lentil) - 3200,,
Wapanucka limestone 100 150
Caney shale 1500 ft.
\Voodford chert fioo ft.
Hunton limestone i6o ft.
Sylvan shale (upper part) 50 100
Sylvan shale (lower part) 250 ft.
Viola limestone 750
Simpson series 1600,,
Arbuckle limestone 4000--6000,,
Regan sandstone. 50 100 ft.
Tishomingo granite (?)
Composite section. The upper part is taken from vicinty of Coalgate, the lower part from the vicinity of Atoka.
WEST CENTRAL CoLoRADo Eocene or later.
Ruby formation 2500 ft.
Ohio formation (local only) 200 ft.
Laramie formation 2000 ft.
Montana formation 2800
Niobrara formation 100 200.,
Benton formation 150 300
Dakota formation 40 300 Jurassic.
Gunnison formation 350 500 ft.
Maroon conglomerate 4500 ft.
Weber limestone 100 550 ft.
Leaciville limestone 400 525 ft.
Yule limestone 350 450 ft. Upper Cambrian.
Sawatch quartzite 50 350 ft.
THE BIGHORN MOUNTAINS OF WYOMING
Dc Smet formation (shale and sandstone) 4000 ft.
Kingsbury conglomerate 01500,,
Piney formation (shale and sandstone) - 2500,,
Parkman sandstone 350,,
Pierre shale I5003500
Colorado formation 1050-1700
Cloverly formation (upper part may be Cretaceous) 30- 300 ft.
Morrison formation (may be Jurassic). 100 300,, Jurassic.
Sundance formation 250 350 ft. Unconformity.
Triassic and Permian.
Chugwater formation 7501200 ft.
Tensleep sandstone 30 150 ft.
Amsden sandstone 150 350,,
Madison limestone 1000 ft.
Bighorn limestone 300 ft.
Deadwood formation 900 ft.
This section is fairly representative for the Rocky Mountains.
Terrace deposits and dune sand.
Paso Robles formation 1000 +ft.
Pismo formation (in south part of area). 3000 *ft. Santa Margarita (in north part of area). 1550 * Unconformity.
Vaquero sandstone 0 500
Toro formation (Knoxville) 3000* ft.
San Luis formation (Franciscan). .. 1000 ~ ft.
This section is representative of the southern Pacific coast.
SECTION IN CENTRAL WASHINGTON
Howson andesite 250 ft.
Keechelus andesite series 4000 ft.
Guye formation (sedimentary beds with some lava flows) 3500 ~ ft.
Roslyn formation (sandstone and shale; coal) C. 3000 ft.
Teanaway basalt 4000
Kachess rhyolite 02000
Swauk formation (clastic rocks with some tufT, &c.) 2005000
Igneous and metamorphic rocks.
This section is representative of the north-west part of the country. BIBLIOGRAPHYA detailed bibliography for North American geology from 1732 to 1891, inclusive, is given in U.S. Geological Survey Bulletin 527 (1896); for I8921900 in Bulletin z88 (1902); for1901-1905in Bull. 301 (1906); for1906-1907in Bull. 372 (1909);
for 1908 in Bull. 409 (1909), &c. A few of the more important and available publications are enumerated below.
General Treatises.T. C. Chamberlin and R. D. Salisbur Geologic Processes (New York) and Earth History (2 vols., New York J. D. Dana, Manual of Geology (New York, 1862); W. B. Scott, Introduction to Geology (New York, 1897); and Joseph Le Conte, Elements of Geology (New York, 1878).
Official Reports.F. V. Hayden, Reports of the U.S. Geological and Geographical Survey of the Territories (12 vols., Washington, 1873I883); Clarence King, Geological Exploration of the Fortieth Parallel (~ vols. and atlas, Washington, 1870-1880); George M. Wheeler, Geographical and Geological Exploration and Surveys West of the iooth Meridian (7 vols. and 2 atlases, Washington, 1877-1879); and Reports of the U.S. Geological Survey (since 1880): (I) Monographs on special topics and areas, about 50 in number; (2) Professional Papersmonographic treatment of somewhat smaller areas and lesser topics, about 60 in number; (3) Bulletins, between 300 and 400 in number; and (4) Annual Reports (previous to 1903) containing many papers of importance, of the sort now published as Professional Papers. Reports of state geological surveys have been published by most of the states east of the Missouri river, and some of those farther west (California, Washington, Kansas, Nebraska and Wyoming) and south (Arkansas, Texas and Louisiana). Among the more important periodicals are the Bulletin of the Geological Society of America (Rochester, N.Y., 1889 seq.); the American Journal of Science (New Haven, Conn., 1818 seq.); the American Geologist (Minneapolis, i888 seq.); Journal of Geology (Chicago, 1893 seq.); Economic Geology (Lancaster, Pa., 1905 seq.). Occasional articles of value are to be found in the American Naturalist and Science, and in the Transactions and Proceedings of various state and municipal academies of science, societies, &c. (R. D. S.; T. C. C.)
The chief features of the climate of the United States may be best apprehended by relating them to the causes by which they are controlled. Two leading features, from which many others follow, are the intermediate value of the mean annual temperatures and the prevalence of westerly winds, with which drift the areas of high and low pressurecyclonic and anticyclonic areascontrolling the short-lived, non-periodic weather changes. The first of these features is determined by the intermediate position of the United States between the equator and the north pole; the second by the equatorial-polar temperature contrast and the eastward rotation of the planet. Next, dependent on the inclination of the earths axis, is the division of the planetary year into the terrestrial seasons, with winter and summer changes of temperature, wind-strength and precipitation: these seasonal changes are not of the restrained measure that is characteristic of the oceanic southern temperate zone, but of the exaggerated measure appropriate to the continental interruptions of ~the northern land-and-water zone, to which the term temperate is so generally inapplicable. The effects of the continent are already visible in the mean annual temperatures, in which the poleward temperature gradient is about twice as strong as it is on the neighboring oceans; this being a natural effect of the immobility of the land surface, in contrast to the circulatory movement of the ocean currents, which thus lessen the temperature differences due to latitude: on the continent such differences are developed in full force. Closely associated with the effect of continental immobility are the effects dependent on the low specific heat and the opacity of the lands, in contrast with the high specific heat and partial transparence of the ocean waters. In virtue of these physical characteristics, the air over the land becomes much warmer in summer and much colder in winter than the air over the oceans in corresponding latitudes; hence the seasonal changes of temperature in the central United States are strong; the high temperatures appropriate to the torrid zone advance northward to middle latitudes in summer, and the low temperatures appropriate to the Arctic regions descend almost to middle latitudes in winter. As a result, the isotherms of July are strongly convex poleward as they cross the United States, the isotherm of 70 Sweeping up to the northern boundary in the north-west, and the heat equator leaping to the overheated deserts of the south-west, where the July mean is over 90. Conversely, the isotherms of January are convex southward, with a monthly mean below 32 in the northern third of the interior, and of zero on the mid-northern boundary. The seasonal bending of the isotherms is, however, unsymmetrical for several reasons. The continent being interrupted on its eastern side by the Gulf of Mexico and Hudson Bay, with the Great Lakes between these two large water bodies, the northward bending of the July isotherms is most pronounced in the western part of the United States. Indeed the contrast between the moderate temperatures of the Pacific coast and the overheated areas of the next interior deserts is so great that the isotherms trend almost parallel to the coast, and are even overturned somewhat in southern California, where the most rapid increase of temperatures in July is found not by moving southward over the ocean toward the equator, but north-eastward over the land to the deserts of Nevada and Arizona. So strong is the displacement of the area of highest interior temperatures westward from the middle of the continent that the Gulf of California almost rivals the Red Sea as an ocean-arm under a desert-hot atmosphere. In the same midsummer month all the eastern half of the United States is included between the isotherms of 66 and 82; the contrast between Lake Superior and the coast of the Gulf of Mexico, 1200 m. to the south, is not so great as between the coast of southern California and the desert 15o m. inland to the north-east. In January the northern water areas of the continent are frozen and snow-covered; Hudson Bay becomes unduly cold, and the greatest southward bending of the isotherms is somewhat east of the continental axis, with an extension of its effects out upon the Atlantic; but the southward bending isotherms are somewhat looped back about the unfrozen waters of the lower Great Lakes. In the midwinter month, it is the eastern half of the country that has strong temperature contrasts; the temperature gradients are twice as strong between New Orleans and Minneapolis as on the Pacific coast, and the contrast between Jacksonville, Fla., and Eastport, Me., is about the same as between San Diego, Cal., and the Aleutian Islands.
The strong changes of temperature with the seasons are indicated also by the distribution of summer maxima and winter minima; summer temperatures above 112 are known in the south-western deserts, and temperatures of 100 are sometimes carried far northward on the Great Plains by the hot winds nearly to the Canadian boundary; while in winter, temperatures of 40 occur along the mid-northern boundary and freezing winds sometimes sweep down to the border of the Gulf of Mexico. The temperature anomalies are also instructive: they rival those of Asia in value, though not in area, being from 15 to 20 above the mean of their latitude in the northern interior in summer, and as much below in winter. The same is almost true of the mean annual range (mean of July to mean of January), the states of the northern prairies and plains having a mean annual range of 70 and an extreme range of 135. In this connection the effect of the prevailing winds is very marked. The equalizing effects of a conservative ocean are brought upon the Pacific coast, where the climate is truly temperate, the mean annual range being only 10 or 12, thus resembling western Europe; while the exaggerating effects of the continental interior are carried eastward to the Atlantic coast, where the mean annual range is 40 or 50.
The prevailing winds respond to the stronger poleward temperature gradients of winter by rising to a higher velocity and a more frequent and severer cyclonic storminess; and to the weaker gradients of summer by relaxing to a lower velocity with fewer and weaker cyclonic storms; but furthermore the northern zone occupied by the prevailing westerlies expands as the winds strengthen in winter, and shrinks as they weaken in summer; thus the stormy westerlies, which impinge upon the north-western coast and give it plentiful rainfall all through the year, in winter reach southern California and sweep across part of the Gulf of Mexico and Florida; it is for this reason that southern California has a rainy winter season, and that the states bordering on the Gulf of Mexico are visited in winter by occasional intensified cold winds, inappropriate to their latitude. In summer the stormy westerly winds withdraw from these lower latitudes, which are then to be more associated with the trade winds. In California the effect of the strong equatorward turn of the summer winds is to produce a dry season; but in the states along the Gulf of Mexico and especially in Florida the withdrawal of the stormy westerlies in favor of the steadier trade winds (here turned somewhat toward the continental interior, as explained below) results in an increase of precipitation. The general winds also are much affected by the changes of pressure due to the strong continental changes of temperature. The warmed air of summer produces an area of low pressure in the west-central United States, which interrupts the belt of high pressure that planetary conditions alone would form around the earth about latitude 30; hence there is a tendency of the summer winds to blow inward from the northern Pacific over the Cordilleras toward the continental centre, and from the trades of the torrid Atlantic up the Mississippi Valley; conversely in winter time, the cold air over the lands produces a large area of high pressure from which the winds tend to flow outward; thus repelling the westerly winds of the northern Pacific and greatly intensifying the outflow southward to the Gulf of Mexico and eastward to the Atlantic. As a result of these seasonal alternations of temperature and pressure there is something of a monsoon tendency developed in the winds of the Mississippi Valley, southerly infiowing winds prevailing in summer and northerly outfiowing winds in winter; but the general tendency to inflow and outflow is greatly modified by the relief of the lands, to which we next turn.
The climatic effects of relief are seen directly in the ascent of the higher mountain ranges to altitudes where low temperatures prevail, thus preserving snow patches through the summer on the high summits (over 12,000 ft.) in the south, and maintaining snowfields and moderate-sized glaciers on the ranges in the north. With this goes a general increase of precipitation with altitude, so that a good rainfall map would have its darker shades very generally along the mountain ranges. Thus the heaviest measured rainfall east of the Mississippi is on the southern Appalachians; while in the west, where observations are as yet few at high level stations, the occurrence of forests and pastures on the higher slopes of mountains which rise from desert plains clearly testifies to the same rule. The mountains also introduce controls over the local winds; diurnal warming in summer suffices to cause local ascending breezes which frequently become cloudy by the expansion of ascent, even to the point of forming local thunder showers which drift away as they grow and soon dissolve after leaving the parent mountain. Conversely, nocturnal cooling produces well-defined descending breezes which issue from the valley mouths, sometimes attaining an unpleasant strength toward midnight.
The mountains are of larger importance in obstructing and deflecting the course of the general winds. The Pacific ranges, standing transverse to the course of the prevailing westerlies near the Pacific Ocean, are of the greatest importance in this respect; it is largely by reason of the barrier that they form that the tempering effects of the Pacific winds are felt for so short a distance inland in winter, and that the heat centre is displaced in summer so far towards the western coast. The rainfall from the stromy westerly winds is largely deposited on the western slopes of the mountains near the Pacific coast, and arid or desert interior plains are thus found close to the great ocean. The descending winds on the eastern slopes of the ranges are frequently warm and dry, to the point of resembling the Fhn winds of the Alps; such winds are known in the Cordilleran region as Chinook winds. The ranges of the Rocky Mountains in their turn receive some rainfall from the passing winds, but it is only after the westerlies are reinforced by a moist indraft from the Gulf of Mexico and the Atlanticthe result of summer or of cyclonic inflowthat rainfall increases to a sufficient measure on the lower lands to support agriculture without irrigation. The region east of the Mississippi is singularly favored in this way; for it receives a good amount of rainfall, well distribu ted through the year, and indeed is in this respect one of the largest regions in the temperate zones that are so well watered. The Great Plains are under correspondingly unfavourable conditions, for their scanty rainfall is of very variable amount. Along the transition belt between plains and prairies the climate is peculiarly trying as to rainfall; one series of five or ten years may have sufficient rainfall to enable the farmers to gather good crops; but the next series following may be so dry that the crops fail year after year.
The cyclonic inflows and anticyclonic outflows, so characteristic of the belt of westerly winds the world over, are very irregular in the Cord illeran region; but farther eastward they are typically developed by reason of the great extent of open country. Although of reduced strength in the summer, they still suffice to dominate weather changes; it is during the approach of a low pressure centre that hot southerly winds prevail; they sometimes reach so high a temperature as to wither and blight the grain crops; and it is almost exclusively in connection with the cloudy areas near and south-east of these cyclonic centres that violent thunderstorms, with their occasional destructive whirling tornadoes, are formed. With the passing of the low pgessure centre, the winds shift to west or northwest, the temperature falls, and all nature is relieved. In wintertime, the cyclonic and anticyclonic areas are of increased frequency and intensity; and it is partly for this reason that many meteorologists have been disposed to regard them as chiefly driven by the irregular flow of the westerly winds, rather than as due to convectional instability, which should have a maximum effect in summer. One of the best indications of actual winter weather, as apart from the arrival of winter by the calendar, is the development of cyclonic disturbances of such strength that the change frcm their warm, sirocco-like southerly inflow hi front of their centre, to the cold wave of their rear produces lion-periodic temperature changes strong enough to overcome the weakened diurnal temperature changes of the cold season, a relation which practically never occurs in summer time. A curious feature of the cyclonic storms is that, whether they cross the interior of the country near the northern or southern boundary or along an intermediate path, they converge towards New England as they pass on toward the Atlantic; and hence that the north-eastern part of the United States is subjected to especially numerous and strong weather changes. (W. M. D.)
Fauna.Differences of temperature have produced in North America seven transcontinental life-zones or areas characterized by relative uniformity of both fauna and flora; they are the Arctic, Hudsonian and Canadian, which are divisions of the Boreal Region; the Transition, Upper Austral and Lower Austral, which are divisions of the Austral Region, and the Tropical. The Arctic, Hudsonian and Canadian enter the United States from the north and the Tropical from the south; but the greater part of the United States is occupied by the Transition, Upper Austral and Lower Austral, and each of these is divided into eastern and western subzones by differences in the amount of moisture. The Arctic or ArcticAlpine zone covers in the United States only the tops of a few mountains which extend above the limit of trees, such as Mt Katahdin in Maine, Mt Washington and neighboring peaks in the White Mountains of New Hampshire, and the loftier peaks of the Rocky, Cascade and Sierra Nevada Mountains. The larger animals are rare on these mountain-tops and the areas are too small for a distinct fauna. The Hudsonian zone covers the upper slopes of the higher mountains of New England, New York and North Carolina and larger areas on the elevated slopes of the Rocky and Cascade Mountains; and on the western mountains it is the home of the mountain goat, mountain sheep, Alpine flying-squirrel, nutcracker, evening grosbeak and Townsends solitaire. The Canadian zone crosses from Canada into northern and northwestern Maine, northern and central New Hampshire, northern Michigan, and north-eastern Minnesota and North Dakota, covers the Green Mountains, most of the Adirondacks and Catskills, the higher slopes of the mountains in Pennsylvania, West Virginia, Virginia, western North Carolina and eastern Tennessee, the lower slopes of the northern Rocky and Cascade Mountains, the upper slopes of the southern Rocky and Sierra Nevada Mountains, and a strip along the Pacific coast as far south as Cape Mendocino, interrupted, however, by the Columbia Valley. Among its characteristic mammals and birds are the lynx, marten, porcupine, northern red squirrel, Beldings and Kennicotts ground squirrels, varyin and snowshoe rabbits, northern jumping mouse, white-throate sparrow, Blackburnian warbler, Audubon. warbler, olive-backed thrush, three-toed woodpecker, spruce grouse, and Canada jay; within this zone in the North-eastern states are a few moose and caribou, but farther north these animals are more characteristic of the Hudsonian zone. The Transition zone, in which the extreme southern limit of several boreal species overlaps the extreme northern. limit of numerous austral species, is divided into an eastern humid or Alleghanian area, a western arid area, and a Pacific coast humid area. The Alleghanian area comprises most of the lowlands of New England. New York and Pennsylvania, the north-east corner of Ohio, most of the lower peninsula of Michigan, nearly all of Wisconsin, more than half of Minnesota, eastern North Dakota, north-eastern South Dakota, and the greater part of the Appalachian Mountains from Pennsylvania to Georgia. It has few distinctive species, but within its borders the southern mole and cotton-tail rabbit of the South meet the northern star-nosed and Brewers moles and the varying hare of the North, and the southern bobwhite, Baltimore oriole, bluebird, catbird, chewink, thrasher and wood thrush are neighbors of the bobolink, solitary vireo and the hermit and Wilson s thrushes. The Arid Transition life-zone comprises the western part of the Dakotas, north-eastern Montana, and irregular areas in Washington, Oregon, Idaho, Wyoming, California, Nevada, Utah, Colorado, Arizona, New Mexico and western Texas, covering for the most part the eastern base of the Cascade and Sierra Nevada Mountains and the higher parts of the Great Basin and the plateaus. Its most characteristic animals and birds are the white-tailed jack-rabbit, pallid vole, sage hen, sharp-tailed grouse and greentailed towhee; the large Columbia ground-squirrel (Spermophflus columbianus) is common in that part of the zone which re west of the Rocky Mountains, but east of the Rockies it is replaced by another species (Cynomys) which closely resembles a small prairie dog. The Pacific Coast Transition life-zone comprises the region between the Cascade and Coast ranges in Washington and Oregon, parts of northern California, and most of the California coast region from Cape Mendocino to Santa Barbara. It is the home of the Columbia black-tail deer, western raccoon, Oregon spotted skunk, Douglas red squirrel, Townsends chipmunk, tailless sewellel (Haplodcn rufus), peculiar species of pocket gophers and voles, Pacific coast forms of the great-horned, spotted, screech and pigmy owls, sooty grouse, Oregon ruffed grouse, Stellers jay, chestnutbacked chickadee and Pacific winter wren. The Upper Austral zone is divided into an eastern humid (or Carolinian) area and a western arid (or Upper Sonoran) area. The Caiolinian area extends from southern Michigan to northern Georgia and from the Atlantic coast to Western Kansas, comprising Delaware, all of Maryland except the mountainous Western portion, all of Ohio except the north-east corner, nearly the whole of Indiana, Illinois, Iowa and Missouri, eastern Nebraska and Kansas, south-eastern South Dakota, western central Oklahoma, northern Arkansas, middle and eastern Kentucky, middle Tennessee and the Tennessee valley in eastern Tennessee, middle Virginia and North Carolina, western \Vest Virginia, north-eastern Alabama. northern Georgia, western South Carolina, the Connecticut Valley in Connecticut, the lower Hudson Valley and the Erie basin in New York, and narrow belts along the southern and Western borders of the lower peninsula of Michigan. It is the northernmost home of the opossum, grey fox, fox squirrel, cardinal bird, Carolina wren, tufted tit, gnat catcher, summer tanager and yellow-breasted chat. The Upper Sonoran life-zone comprises south-eastern Montana, central, eastern and north-eastern Wyoming, a portion of south-western South Dakota, western Nebraska and Kansas, the western extremity of Oklahoma, north-western Texas, eastern Colorado, south-eastern New Mexico, the Snake plains in Idaho, the Columbia plains in Washington, the Malheur and Harney plains in Oregon, the Great Salt Lake and Sevier deserts in Utah, and narrow belts in California, Nevada and Arizona. Among its characteristic mammals and birds are the sage cotton-tail, black-tailed jack-rabbit, Idaho rabbit, Oregon, Utah and Townsends ground squirrels, sage chipmunk, fivetoed kangaroo rats, pocket mice, grasshopper mice, burrowing owl, Brewers sparrow, Nevada sage sparrow, lazuli finch, sage thrasher, Nuttall s poor-will, Bullocks oriole and rough-winged swallow. The Lower Austral zone occupies the greater part of the Southern states, and is divided near the 98th meridian into an eastern humid or Austroriparian area and a western arid or Lower Sonoran area. The Austroriparian zone comprises nearly all the Gulf States as far West as the mouth of the Rio Grande, the greater part of Georgia, eastern South Carolina, North Carolina and Virginia, and extends up the lowlands of the Mississippi Valley acru_~s western Tennessee and Kentucky into southern Illinois andlndiana and across eastern and southern Arkansas and eastern Oklahoma into south-eastern Missouri and Kansas. It is the home of the southern fox-squirrel, Cotton rat, ricefield rat, wood rat, free-tailed bat, mocking bird, painted bunting, prothonotary warbler, red-cockaded woodpecker, chuckwills-widow, and the swallow-tailed and Mississippi kites. A southern portion of this zone, comprising a narrow strip along the Gulf Coast from Texas to Florida and up the Atlantic coast to South Carolina, is semi-tropical, and is the northernmost habitation of several small mammals, the alligator (Alligator mississippiensis), the ground dove, white-tailed kite, Florida screech owl and Chapman s night-hawk. The Lower Sonoran zone comprises the most arid parts of the United States: south-western Texas, south-western Arizona and a portion of northern Arizona, southern Nevada and a large part of southern California. Some of its characteristic mammals and birds are the long-eared desert fox, four-toed kangaroo rats, Sonoran pocket mice, big-eared and tiny white-haired bats, road runner, cactus wren, canyon wren, desert thrashers, hooded oriole, black-throated desert sparrow, Texas night-hawk and Gambels quail. It is the northernmost home of the armadillo, ocelot, jaguar, red and grey cats, and the spiny pocket mouse, and in southern Texas especially it is visited by several species of tropical birds. There is some resemblance to the Tropical life-zone at the south-eastern extremity of Texas, but this zone in the United States is properly restricted to southern Florida and the lower valley of the Colorado along the border of California and Arizona, and the knowledge of the latter is very imperfect. The area in Florida is too small for characteristic tropical mammals, but it has the true crocodile (Crocodilus americanus) and is the home of a few tropical birds. Most of the larger American mammals are not restricted to any one faunal zone. The bison, although now nearly extinct, formerly roamed over nearly the entire region between the Appalachian and the Rocky Mountains. The black bear and beaver were also widely distributed. The Virginia deer still ranges from Maine to the Gulf states and from the Atlantic coast to the Rocky Mountains. The grizzly bear, cougar, coyote, prairie dog and antelope are still found in several of the Western states, and the grey wolf is common in the West and in northern Minnesota, \Visconsin and Michigan.
Flora.The Alpine flora, which is found in the United States only on the tops of those mountains which rise above the limit of trees, consists principally of a variety of plants which bloom as soon as the snow melts and for a short season make a brilliant display of colors. The flora of the Hudsonian and the Canadian zone consists largely of white and black spruce, tamarack, canoe-birch, balsam-poplar, balsam-fir, aspen and grey pine. In the Alleghanian Transition zone the chestnut, walnut, oaks and hickories of the South are interspersed among the beech, birch, hemlock and sugar maple of the North. In the Western Arid Transition zone the flora consists largely of the true sage brush (A rtemisia trident ata), but some tracts are covereci with forests of yellow or bull pine (Pinus ponderosa). The Pacific coast Transition zone is noted for its forests of giant conifers, principally Douglas fir, Sitka spruce, Pacific cedar and Western hemlock, Here, too, mosses and ferns grow in profusion, and the sadal (Gaultheria shailon), thimble berry (Rubus nootkamus), salmon berry (Rubus spectabilis) and devils club ,(Fatsia horr-ida) are characteristic shrubs. In the Carolinian zone the tulip tree, sycamore, sweet gum, rose magnolia, short-leaf pine and sassafras find their northernmost limit Sage brush is common to both the western arid Transstion zone and the Upper Sonoran zone, but in suitable soils of the latter several greasewoods (Artiplex confertifolia, A. canescens, A. nultalli, Tetradymia canescens, Sarcobatus vermiculatus and Gray-ia spinosa) are characteristic species, and on the mountain slopes are some nut pines (psif on) and junipers. The Austroriparian zone has the long-leaf and loblolly pines, magnolia and live oak on the uplands, and the bald cypress, tupelo and cane in the swamps; and in the semi-tropical Gulf strip are the cabbage palmetto and Cuban pine; here, too, Sea Island cotton and tropical fruits are successfully cultivated. The Lower Sonoran zone is noted for its cactuses, of which there is a great variety, and some of them grow to the height of trees; the mesquite is also very large, and the creosote bush, acacias, yuccas and agaves are common. The Tropical belt of southern Florida has the royal palm. coco-nut palm, banana, Jamaica dogwood, manchineel and mangrove; the Tropical belt in the lower valley of the Colorado has giant cactuses. desert acacias, palo-verdes and the Washington or fan-leaf palm. Almost all of the United States east of the 98th meridian is naturally a forest region, and forests cover the greater part of the Rocky Mountains, the Cascades, the Sierra Nevadas and the Coast Range, but throughout the belt of plains, basins and deserts west of the Rocky Mountains and on the Great Plains east of the Rocky Mountains there are few trees except along the watercourses, and the prevailing type of vegetation ranges from bunch grass to sage brush and cactuses according to the degree of aridity and the temperature. In the eastern forest region the number of species decreases somewhat from south to north, but the entire region differs from the densely forested region of the Pacific Coast Transition zone in that it is essentially a region of deciduous or hardwood forests, while the latter is essentially one of coniferous trees; it differs from the forested region of the Rocky Mountains in that the latter is not only essentially a region of coniferous trees, but one where the forests do not by any means occupy the whole area, neither do they approach in density or economic importance those of the eastern division of the country. Again, the forests of most of the eastern region embrace a variety of species, which, as a rule, are very much intermingled, and do not, unless quite exceptionally, occupy areas chiefly devoted to one species; while, on the other hand, the forests of the westincluding both Rocky Mountain and Pacific coast divisionsexhibit a small number of species, considering the vast area embraced in the region; and these species, in a number of instances, are extraordinarily limited in their range, although there are cases in which one or two species have almost exclusive possession of extensive areas.
BIBLIOGRAPHY.C. H. Merriam, Life Zones and Crop Zones of the United States, Bulletin No. 10 of the United States Department of Agriculture, Division of Biological Survey (Washington, 1898); I. C. Russell, North America (New York, 1904); W. T. Hornaday, American Natural History (New York, 1904); W. Stone and W. E. Cram, American Animals (New York, 1902); E. Coues, Key to North American Birds (Boston, 1896); Florence M. Bailey, Handbook of Birds of the Western United States (Boston, 1902); E. D. Cope, The Crocodilians, Lizards and Snakes of North America, in the Report of the United States National Museum for the year 1898 (Washington, 1900); L. Stejneger, The Poisonous Snakes of North America, ibid., 1893 (Washington, 1895). (N. D. M.)
The achievement of independence found the people of the United States owning the entire country between the Gulf and the Great Lakes, excepting only Florida, as far to the west as the Mississippi; but the actual settlements were, with a few minor exceptions, confined to a strip of territory along the Atlantic shore. The depth of settlement, from the coast inland, varied greatly, ranging from what would be involved in the mere occupation of the shore for fishing purposes to a body of agricultural occupation extending back to the base of the great Atlantic chain, and averaged some 250 m.i Westward, beyonc the general line of continuous settlement, were four extensions of population through as many gaps in the Appalachian barrier, constituting the four main paths along which migration westward first took place: the Mohawk Valley in New York, the upper Potomac, the Appalachian Valley, and around the southern base of the Appalachian system. Four outlying groups beyond the mountains, with perhaps a twentieth part of the total population of the nation, one about Pittsburg, one in West Virginia, another in northern Kentucky, and the last in. Ten.nessee: all determined in situalion by river highwaysbore witness to the qualities of strength and courage of the American pioneer. Finally, there were in 1790 about a score of small trading or military posts, mainly of French origin, scattered over the then almost unbroken wilderness of the upper Mississippi Valley and region of the Great Lakes.
Twelve decennial censuses taken since that time (18oo191o) have revealed the extraordinary spread of population over the present area of the country (see CENSUS: United StoJes). The large percentage of the population, particularly Continental United Populatin enumerated.
Total populatin. T,
Number of foreign ~ immi~rants Population Population ~ entennf in ~ensus within area within added. preceding ears. of 1790. area. Number. .8 ~ decide. Total.
1790 3,929,625 3,929,214 819,41
1800 5,247,355 61,128 5,308,483 35.1 819,41
1810 6,779,308 460,573 7,239,881 36~4 1,698,11
1820 8,293,869 1,344,584 9,638,453 33-I 250,000t I,752,3~
1830 10,240,232 2,625,788 I2,860,69~ 335 143,439 I,752,3~
1840 11,781,231 5,288,222 17,063,353 32.7 599,125 I,752,3~
1850 14,569,584 8,622,292 23,191,876 359 1,713,251 2,939,0~
r86o 17,326,157 14,117,164 31,443,321 356 2,598,214 2,97O,o~
1870 19,687,504 18,870,867 38,558,371 226 2,314,824 2,970,0
1880 23,925,639 26,263,570 50,155,783 30~I 2,812,191 2,970,0
1890 28,188,321 34,791,445 ~2,947,7f4 24.9 5,246,613 2,970,0,
1900 33,533,630 42,749,757 75,994,575* 20-7 3,844,420 2,970,1,
1910 91,972,266* 21O 7,753,8I6~
~ Total, 27,604,509, exclusive of at least some hundreds of thousands Louisiana purchase from France.
II Florida purchase from Spain; population counted first, 1830.
Annexation of Texas (385,926 sq. m.); peace cession from Me sq. rn).
of the great urban centres, that is established to-day in the river lowlands, reflects the role that water highways have played in the peopling of the country. The dwindlings and growths of Nevada down to the present day, and to not a slight degree the general history of the settlement of the states of the Rocky Mountain region, arc a commentary on the fate of mining industries. The initial settlement of the Pacific coast following the discovery of gold in California in 1848, and of the eastern base of the Rocky Mountains after the discovery of gold in 2859, ifiustrates the same factor. The Mormons settled Utah to insure social isolation, for the security of their theological system. A large part of the Great Plains to the east of the Rockies was taken up as farms in the decade 1880 1890; abandoned afterwards, because of its aridity, to stock grazing; and reconverted from ranches into farms when a system of dry farming had proved its tillage practicable. The negro more or less consciously moves, individufily, closer into the areas whose climate and crops most nearly meet his desires and capabilities as a farmer; and his race as i whole unconsciously is adjusting its habitat to the boundar es of the Austroriparian life zone. The countrys centre of population in 110 years moved more than 5oo m westward, almost exactly along the 39th parallel of latitude: 9.5 degrees of longitude, with an extreme variation. of less than 19 minutes of latitude.
Growth of tile Nation in Population.If the I9th century was remarkable with respect to national and urban growth the world over, it was particularly so in the growth of the United States. Malthus expressed the opinion that only in such a land of unlimited means of living could population. freely increase.
The total population increased from 1800 to 1900 about fourteen fold (1331.6%).i The rate of growth indicated in 1900 was still double the average rate of western Europe.2 In the whole world Argentina alone (1869-1895) showed equal (and greater) growth. At the opening of the century not only all the great European powers of to-day but also even Spain and Turkey exceeded the United States in numbers; at its close only Russia. At the census of 1910, while the continental United States population (excluding Alaska) was 91,972,266, the total, including Alaska, Hawaii and Porto Rico, but excluding the Philippine Islands, Guam, Samoa and the Canal Zone, was 93,402,151.
States, exclusive of Alaska, Areas (excluding water), in square miles.
tal area. Settled area.
Total area covered by Density of population.
Area Area with Estimated 8
acquired in not less than ,area of preceding two persons isolated o decade, per sq. m. settlements Total. s ~ ~, ~
beyond the, a general h,i~ 0 0
frontier. ~ si g. o a .~ ~
6 239,935 13,850 417,170 16.4 9.4 9.6
6 305,708 33,800 434,670 17-4 126 0-2 122
7 878,641f 407,945 25,100 556,010 177 16.3 o8 13-0
.7 54,24O~ 508,717 4,200 688,670 18-9 f99 24 13-9
7 632,717 4,700 877,170 20.3 24-5 4~3 14.5
7 807,292 2,150 1,183,870 2f~I 28.2 7.1 24.4
1 I,i86,674~f 979,249 38,375 1,519,170 23.7 34.9 5.3 15.2
,8 31,017* 1,194,754 107,375 1,951,520 26.3 41.5 5.7 16I
,8 1,272,239 131,910 2,126,290 303 47.2 7.6 13.4
8 1,569,565 260,025 2,727,454 32.0 57.4 Io6 184
8 1,947,280 2,974,159 32.2 67.6 13-6 19.2
8 100 1,925,590 2,974,159 395 80.4 16-7 25.5
2,974,159 309 Dad (5318 lfl 1830; 6100 in 1840; 91,219 in 1900).
of Canadians and Mexicans.
ico (520,068 sq. m.); extinction of British claims to Oregon (280,680
In 1790 there were about 600,000 white families in the United States. Speaking broadly, there were few very rich and few very poor. Food was abundant. Both social traditiolis and the religious beliefs of the people encouraged fecundity. The country enjoyed domestic tranquillity. All this time, too, the land was but partially settled. Mechanical labor was scarce, and even. upon the farm it was difficult to command hired service, almost the only farm laborers down to 185o, in the north, being young men who went out to work for a few years to get a little money to marry upon. A change was probably inevitable and came, apparently, between 1840 and 1850.
The accessions in that decade from Ireland and Germany were enormous, the total immigration rising to 1,713,251 against 599,125 during the decade preceding, and against only 143,439 from 2820 to 1830. These people came in condition to breed with unprecedented rapidity, under the stimulus of an abundance, 2According to Lavasseur and Bodio, 14.5% from 1860 to 1880;
2I~2% from 1880 to I9o0; from 1886-1900, 11.0%.
in regard to food, shelter and clothing, such as the most fortunate of them had never known. Yet in spite of these accessions, the population of the country realized a slightly smaller proportion of gain than when the foreign arrivals were almost insignificant.
For a time the retardation of the normal rate of increase among the native population was concealed from view by the extraordinary immigration. In the decade1850-1860it was seen that almost a seventh of the population of the country consisted of persons born abroad. From 1840 to 1860 there came more than four million. immigrants, of whom probably three and a half million, with probably as many children born in America, were living at the latter date.
The ten years from 1860 to 1870 witnessed the operation of the first great factor which reduced the rate of national increase, namely the Civil War. The superintendent of the Ninth Census, 1870, presented a computation 01 the effects of this causefirst, through direct losses, by wounds or disease, either in actual service of the army or navy, or in a brief term following discharge; secondly, through the retardation of the rate of increase in the colored element, due to the privations, exposures and excesses attendant upon emancipation; thirdly, through the check given to immigration by the existence of war, the fear of conscription, and the apprehension abroad of results prejudicial to the national welfare. The aggregate effect of all these causes was estimated a~ a loss, to the population of 1870 of 1,765 ,o00. Finally, the temporary reduction of the birth-rate, consequent upon the withdrawal of perhaps one-fourth of the national militia (males of 18 to 44 years) during two-fifths of the decade, may be estimated at perhaps 750,000.
The Tenth Census put it beyond doubt that economic and social forces had been at work, reducing the rate of multiplication. Yet no war had intervened; the industries of the land had flourished; the advance in accumulated wealth had been beyond all precedent; and immigration had increased.
It is an interesting question what has been the contribution of the foreign elements of the countrys population in the growth of the ggregate. This question is closely connected with a still more important one: namely, what effect, if any, has foreign immigration had upon the birth-rate of the native stock. In I850 the foreignborn whites (2,244,602 in number) were about two-thirds of the colored element and one-eighth of the native-white element; in 1870 the foreign-born whites (5,567,229) and the native whites of foreign parentage (5,324,786) each exceeded the colored. In 1900 the two foreign elements constituted one-third of the total population. The absolute numbers of the four elements were: native whites of native parents, 40,949,362; natives of foreign parents, 15,646,017; foreign-born whites, 10,213,817; colored, 8,833,994.
Separating from the total population of the country in 1900 the non-Caucasians (9,185,379), all white persons having both parents foreign (20,803,800), and one-half (2,541,365) of the number of persons having only one parent foreign, the remaining 43,555,250 native inhabitants comprised the descendants of the Americans of 1790, plus those of the few inhabitants of annexed territories, plus those in the third and higher generations of the foreigners who entered the country after 1790 (or for practical purposes, after 1800). The second element may be disregarded. For the exact determination of the last element the census affords no precise data, but affords material for various approximations, based either upon the elimination of the probable progeny of immigrants since 1790; on the known increase of the whites of the South, where the foreign element has always been relatively insignificant; on the percentage of natives having native grandfathers in Massachusetts in 1905; or upon the assumed continuance through the 19th century of the rate of native growth (one-third decennially) known to have prevailed down at least to 1820. The last is the roughest approximation and would indicate a native mass of 50,000,000 in 1900, or a foreign contribution of approximately half. The results of computations by the first two methods yield estimates of the contribution of foreign stock to the native element of 1900 varying among themselves by only 1.8%. The average by the three methods gives 8,539,626 as such contributiOn, making 31,884,791 the total number of whites of foreign origin in 1~oo; and this leaves 35,015,624 as the progeny of the original stock of 1790.1 Adding to the true native whites of 1900 (35,015,624) the native negroes (8,813,658), the increase of the native stock, white and black, since 1790 would thus be about 1091%, and of the whites of 1790 (3,172,006) alone about 1104%. It is evident that had the fecundity of the American stock of 1790 been equal only to that of Belgium (the most fertile population of western Europe in the 19th century) then the additions of foreign elementg to the American people would have been ,by I 900 in heavy preponderance over the original, mainly British., elements. A study of the family names appearing on the census rolls of two prosperous and typical American counties, one distinctively urban and the other rural, in 1790 and I900, has confirmed the popular impression that the British element is growing little, and that the fastest reproducers to-day are the foreign elements that have become large in the immigration current in very recent decades. In applying to the total population of 1790 the rate of growth shown since 1790 by the white people of the South, this rate, for the purpose of the above compirtations, is taken in its entirety only up to 1870, and thereafterin view of the notorious lesser birth-rate since that year in the North and Westonly one half of the rate is used. If, however, application be made of the rate in its entirety from 1790 to 1900, the result would be a theoretical pure native stock in 1900 equal to the then actually existing native and foreign stock combined.
In 1900 more than half of every 100 whites in New England and the Middle states (from New York to Maryland) were of foreign parentage (i.e. had one or both parents foreign), and in both sections the proportion is increasing with great rapidity. The Southern states, on the other hand, have shown a diminishing relative foreign element since 1870, and had in 1900 only 79 of foreign parentage in 1000 whites. Relatively to their share of the countrys aggregate population the North Atlantic states, and those upon the Great Lakesthe manufacturing and urbanized states of the Unionhold much the heaviest share of immigrant population.
The shares of different nationalities in the aggregate mass of foreigners have varied greatly. The family names on the re.~isters of the first census show that more than 90% of the white ulation was then of British stock, and more than 80 was Englis. The Germans were already near 6%. The entry of the Irish began on a great scale after 1840, and in 1850 they formed nearly half of all the foreign-born. In that year 85.6% of this total was made, up by natives of Great Britain and Gei~many. The latter took first place in 1880. In 1900 i~hese two countries represented of the total only 52.7%; add the Dutch, the Danes, Swedes, Norwegians and Swiss to the latter and the share was 65.1%. A great majority of all, of these elements except the British are settled in the states added to the original Unionthe Scandinavians- being the most typically agricultural element; while almost all the other nationalities are in excess, most of them heavily so, in the original states of 1790, where they land, and where they are absorbed into the lower grades of the industrial organization. Since 1880 Italians, Russians, Poles, Austrians, Bohemians and Hungarians have enormously increased in the immigrant population. Germans, Irish, British, Canadians, Scandinavians, Slays and Italians were the leading elements in 1900.
In 1790 the negroes were I9~3% of the countrys inhabitants;, in 1900 only ir6%. While the growth of the countrys aggregate population from 1790 to 1900 was 1833-9%, that of the whites was 2005.9%, and of the negroes only I o667%.
Certain generalizations respecting the South and the North, the East and the. West are essential to an understanding of parts of the history of the past, and of social conditions in the present. For the basis of such comparisons the country is divided by the census into five groups of states:
(I) the North Atlantic division~down to New Jersey and Pennsylvania; (2) the South Atlantic divisionfrom Delaware to Florida (including West Virginia); (3) the North Central divisionincluding the states within a triangle tipped by Ohio, Kansas and North Dakota; (4) the South Central division -covering a triangle tipped by Kentucky, Alabama and Texas; and (5) the Western divisionincluding the Rocky Mountains and Pacific states. The first and third lead to-day in manufacturing interests; the third in agricultural; the fifth in mining.
Groups 1 and 3 (with the western boundary somewhat inde~nite) are colloquially known as the North and 2 and 4 as the South. The two sections started out with population growths in the decade1790-1800very nearly equal (36.5 and 33.7%); but in every succeeding decade before the Civil War the growth of the North was greater, and that of the South less, than its increment in the initial decade. In the two twenty-year periods after 1860 the increases of the North were 61.9 and 48.7%; of the South, 48.4 and 48.5%. In 1790 the two sections were of almost equal population; in 1890, 1900 and 1910 the population of the North was practically double that of the South. In the decade1890-1900the increase of the South exceeded slightly that of the North for the same period owing to the rapid development in recent years of the Southern states west of the Mississippi, which only the Western group ,has exceeded since 1870.1 In general the increase of the two sections every 1000 in the South was as follows from 1790 to 1900
1004; 1025; 1092; 1f8i; 1253; 1455; 1562; 1769; 2057; 1930; 2005
since 1880 has been nearly equal. But while this growth was relatively uniform over the South, in the North there was a low (often a decreasing) rate of rural and a high rate of urban growth. Throughout the 19th century the rates of growth of the North Central division and that of the eastern half of the South Central division steadily decreased. It is notable that that of the South Atlantic group has grown faster since 1860 than ever before, despite the Civil War and the conditions of an. old settled region: a fact possibly due to the effects of the emancipation of the slaves.
Comparing now the population of the regions east and west of the Mississippi, we find that the population of the first had grown from 3,929,214 in 1790 to 55,023,513 in r~oo; and that of the second from 97,401 in f8ro to 20,971,062 in 1900. From 1860 to 1890 the one increased its numbers decennially by one half, and the other by under one fifth; but from 1890 to 1910 the difference in growth was slight, owing to a tremendous falling off in the rate of growth of much of the Western and the western states of the North Central divisions. Only an eighth of the countrys total population lived in I900 west of the 96th meridian, which divides the country into two nearly equal parts. Although, as already stated, the population of the original area of 1790 was passed in 1880 by that of the added area, the natives of the former were still in excess in 1900.
Urban and Rural Population.The five cities of the country that had 8000 or more inhabitants in 1790 had multiplied to 548 in 1900. Only one of the original six (Charleston) was in the true South, which was distinctly rural. The three leading colonial cities, Philadelphia, w York and Boston, grew six-fold in the I 8th century, and fiftyfo in the next. The proportion of the population living in cities seems to have been practically constant throughout the 18th century and up to 1820. The great growth of urban centres has been a result of industrial expansion since that time. This growth has been irregular, but was at a maximum about the middle of the century. On an average throughout the 110 years, the population in cities of 8000 considerably more than doubled every twenty years.i The rate of rural growth, on the other hand, fell very slowly down to 1860,2 and since then. (disregarding the figures of the inaccurate census of 1870) has been steady at about half the former rate. In Rhode Island, in 1900, eight out of every ten persons lived in cities of 8000 or more inhabitants; in Massachusetts, seven in ten. In New York, New Jersey and Connecticut the city element also exceeded half of the population. At the other extreme, Mississippi had only 3% of urban citizens. If the limit be drawn at a population of 2500 (a truer division) the urban. element of Rhode Island becomes 950%; of Massachusetts, 91.5; of Mississippi, 77. All the Southern states are still relatively rural, as well to-day as a hundred years ago. Ten states of the Union had a density in 1910 exceeding 100 persons to the square mile: Illinois (100.7), Delaware (103), Ohio (117), Maryland (130.3), Pennsylvania (171.3), New York (191.2), Connecticut (231.3), NewJersey (~3i~~3), Massachusetts (418.8) and Rhode Island (508.5).
There are abundant statistical indications that the line (be the ~fiuence that draws it economic or social) between urban centres of nly 2500 inhabitants and rural districts is much sharper to-day than was that between the country and cities of 8000 inhabitants (the largest had five times that number) in 1790. The lower limit is therefore a truer division line to-day. Classifying, then, as urban centres all of above 2500 inhabitants, three-tenths of the total population lived in the latter centres in 1880 and four-tenths (3o,583,4f 1) in i~oo; their population doubled in these twenty years. It one regards the larger units, they held naturally a little more of the total population of the countryjust a third (33.1%; ten times their proportion of the countrys total in 1790); and they grew a little faster. The same years, however, made apparent a rapid fall, general and marked, yet possibly only temporary, in the rate at which such urban centres, as well as larger ones, had been gaining upon the rural districts; this reaction being most pronounced in the South and least so in the North Atlantic states, whose manufacturing industries are concentrated in dense centres of population.
Interstate migratIon is an interesting element in American national life. A fifth of the total population of 1900 were living in other states than those of birth; and this does not take account of temporary nor of multiple migration. Every state numbers among its residents natives ot nearly every other state. This movement is complicated by that of foreign immigration. In 1900 the percentage of resident natives varied from 92.7% in South Carolina to 15% in Oklahoma; almost all of the Southern states having high percentages.
SexesThe percentages of males and females, of all ages, in the aggregate population of 1900, were 51.0 and 49.0 respectively. The corresponding figures for the main elements of the population were as follows: for native whites, 50.7 and 49~3; foreign whites, 54.0 and 46.0; negroes, 49.6 and 50.4. The absolute excess of males rn the aggregate population has been progressively greater at every successive census since 1820, save that of 1870Which followed the Civil War, and closed a decade of lessened immigration. The relative excess of males in each unit of population has not constantly progressed, but has been continuous. In densely settled regions females generally predominate; and males in thinly settled regions. In every 1000 urban inhabitants there were, in 1900, 23 (in 1890 only 19) more females than in 1000 rural inhabitants. In the rural districts, so far as there is any excess of females, it is almost solely in the Southern cotton belt, where negro women are largely employed as farm hands.
Vital Statistics, 1900.The median age of the aggregate population of 1900that is, the age that divides the population into halveswas 22.85 years. In 1800 it was 15.97 years. A falling birth-rate, a falling death-rate, and the increase in the number of adult immigrants, are presumably the chief causes of this difference. The median age of the foreign-born in 1900 was 38.42 years. The median age of the population of cities of 25,000 or more inhabitants was 355 years greater than that of the inhabitants of smaller urban centres and rural districts, owing probably in the main to the movement of middle-aged native and foreign adults to urban centres, and the higher birth-rate of the rural, districts. The median age of the aggregate population is highest in New England and the Pacific states, lowest in the South, and in the North Central about equal to the countrys average. The average age of the countrys population in 1900 was 262 years. The United States had a larger proportion (59.1%) within the productive age limits of 15 and 60 years than most European countries; this being due to the immigration of foreign adults (corresponding figure 80.3%), the productive group among the native whites (55.8%) being smaller than in every country of Europe. The same is true, however, of the population over 60 years of age.
The death-rate of the United States, though incapable of exact determination, was probably between 16 and 17 per 1000 in 1900; and therefore less than in most foreign countries.
Th~ following statement of the leading causes of death Death-rate. during the eleven years1890-1900in 83 cities of above 25,000 population, is given by Dr J. S. Billings: Average Annual Death- rate per Ioo,000 Popuia- Consum ti Pneumon Typhoid Diphtheria an tion for the ciues of the p on. a. Fever. croup.
New England.. 244 220 30 77
Middle states.. 259 268 32 101
Lake states.. 156 159 48 79
Southern states - 277 189 50 54
West North Central 183 142 38 61
Among the statistics of conjugal condition the most striking facts are that among the foreign-born the married are more than twice as numerous as the single, owing to the predominance of adults among the immigrants; and the native whites of foreign parents marry late and in much smaller proportion Ma~~
than do the native whites of native parentagethe age. explanation of which is probably to be found in the reaction of the first American generation caused on. one hand by the high American standard of living, and on the other by the relative economic independence of women. In 1900 1.0% of the males and 10.9% of the females from 15 to 19 years of age were married; from 20 to 24 years, 21.6% and 46.5% respectively. Of females above 15 years of age 31.2% were single, 56~9 married, II~2 widowed, 0.5 divorced; many of the last class undoubtedly reporting themselves as of the others. The corresponding figures for males were:
40.2, 54~5, 4.6 and 0.3%. In 1850 there were 56 persons (excluding the slave population) in an average American family; fifty years later there were only 4.7a decline, which was constant, of 16I %. In 1790, 5 persons was also the normal familyi.e. the greatest proportion (14%) of the total were of this size; but in F mill 1900 the model family was that of 3 persons by a more a es. decisive proportion (18%). The minimum state average of 1790, which was 5~4 in Georgia, was greater than the maximum of 1900. Within the area of 1790 there were twice as many families in 1900 as in 1790 consisting of 2 persons, and barely half as many consisting of 7 and upward; New England having shown the greatest and the South the least decrease. In 1790 about a third and in 1900 more than one half of all families had less than 5 members.
The data gathered by the Federal census have never made possible a satisfactory and trustworthy calculation of the birthrate, and state and local agencies possess no such data Birth-rate for any considerable area. But the evidence is on the whole cumulative and convincing that there was a remarkable falling off in the birth-rate during the 19th century. And it may be noted, because of its bearing upon the theory of General Francis A. Walker, that the Old South of 1790, practically unaided by immigration, maintained a rate of increase at least approximatin that attained by other sections of the country by native an foreign stock combined. Not a state of the Union as it existed in 1850 showed an increase, during the half-century following, in the ratio of white children under 16 to fooo white females over f6 years: the ratio declined for the whole country from 1600 to iioo; and it has fallen for the census area of 1790 from 1900 in that year to 1400 in 1850 and 1000 in 1900. On the other hand, elaborate colonial censuses for New York in 1703 and 1812 show Whites under 16 Years per boo Sections of the of Total Population.
Area of 1790 49 483 414 373 344
New England 470 443 358 309 291
Middle states 494 485 405 358 326
Old South 502 508 464 431 402
Added area ---526463 406 368
ratios of 1900 and 2000, and reinforce the suggestions of various other facts that the social, as well as the economic, conditions in colonial times were practically constant.
The decline in the proportion of children since 1860 has been decidedly less in the South (Southern Atlantic and South Central states as defined below) than in the North and West, but in the most recent decades the last section has apparently fast followed New England in having a progressively lesser proportion of children. In the North there was little difference in 1900 in the ratios shown by city and country districts, but in the South the ratio in the latter was almost twice that reported for the former.
The decades 1840-1850,1880-1890and1860-1870have shown much the ~reatest decreases in the percentage of children; and some have attri~uted this to the alleged heavier immigration of foreigners (largely adults)- in the case of the two former decades, and the effects of the Civil War in the third. So also the three decades immediately succeeding the above showed minimum decreases; and this has been attributed to a supposed greater birth-rate among the immiggants.
These uncertainties raise a greater one of much significance, viz. what has been the cause of the reduction in the national birth-rate indicated by the census figures? The question has been very differently judged. In the opinion of General Francis A. Walker, superintendent of the censuses of 1870 and 1880, the remarkable fact that such reduction coincided with a cause that was regarded as certain to quicken the increase of population, viz, the introduction of a vast body of fresh peasant blood from Europe, afforded proof that in this matter of population morals are far more potent than physical causes. The change, wrote General Walker, which produced this falling off from the traditional rate of increase of about 3% per annum, was that from the simplicity of the early times to comparative luxury; involving a rise in the standard of living, the multiplication of artificial necessities, the extension of a paid domestic service, the introduction of women into factory labor.2 In his opinion the decline in the birth-rate coincidently with the increase of immigration, and chiefly in those regions where immigration was greatest, was no mere coincidence; nor was such immigrant invasion due to a weakening native increase, or economic defence; but the decline of the natives was the effect of the increase of the foreigners, which was a shock to the principle of population among the native element. Immigration therefore, according to this theory, had amounted not to a reinforcement of our population, but to a replacement of native by foreign stock. That if the foreigners had not come, the native clement would long have filled the places the foreigners usurped, I entertain says General Walker not a doubt.
It is evident that the characteristics of the factory age to which reference is made above would have acted upon native British as upon any other stock; and that it has universally so acted there is abundant statistical evidence, in Europe and even in a land of such youth and ample opportunities as Australia. The assumption explicitly made by General Walker that among the immigrants no influence was yet excited in restriction of population, is also not only gratuitous, but inherently weak; the European peasant who landed (where the great majority have stayed) in the eastern industrial states was thrown suddenly under the influence of the forces just referred to; forces possibly of stronger influence upon him than upon native classes, which are in general economically and socially more stable, On the whole, the better opinion is probably that of a later authority on the vital statistics of the country, Dr John Shaw Billings,i that though the characteristics of modern life doubtless influence the birth-rate somewhat, by raising the average age of marriage, lessening unions, and increasing divorce and prostitution, their great influence is through the transmutation into necessities of the luxuries of simpler times; not automatically, but in the direction of an increased resort to means for the prevention of child-bearing.
Education.In the article EDucATIoN (United States), and in the articles on the -several states, details are given generally of the conditions of American education. Here the statistics of literacy need only be considered.
In 1900 illiterates (that is, persons unable to write, the 2 See his Discussions in Economics and Statistics, ii. 422, Immigration and Degradation, See the Forum (June, 1893), XV. 467.
majority of these being also unable to read) constituted nearly one-ninth (10.7%) of the population of at least ten years of age; but the greatest part of this illiteracy is due to the negroes and the foreign immigrants. Since 1880 the proportion of illiteracy has steadily declined for all classes, save the foreignborn between 1880 and 1890, owing to the beginning in these years, on a large scale, of immigration from southern Europe. Illiteracy is less among young persons of all classes than in the older age-groups, in which the foreign-born largely fall. This is due to the extension of primary education during the last half of the I 9th century. The older negroes (who were slaves) naturally, when compared with the younger, afford the most striking illustration of this truth. On the other hand, a notable exception is afforded by the native whites of native parents, particularly in the South, where child illiteracy (and child labor) is highest; the declining proportion of illiterates shown by the age~groups of this class up to 24 years is apparently due to a will to learn late in life.
The classification of the illiterate population (above 10 years of age) by races shows that the Indians (56.2%), negroes (44.5%), Chinese (29.0%), Japanese (18.3%), foreign white (13.0%), native white of native parentage (5.7%), and native whites of foreign parents (I6%), are progressively more literate. The advantage of the last as compared with native whites of native parentage is apparently owing to the lesser concentration of these in cities. The percentages of illiterate children for different classes in 1900 were as follows: negroes, 30 I; foreign whites, 56; native whites of foreign parentage, o~ native whites of native parentage, 4~4. There is a greater difference in the North than in the South between the child illiteracy of the Caucasian and non-Caucasian elements; also a ranking of the different sections of the country according to the child illiteracy of one and the other race shows that the negroes of the South stand relatively as high as do its whites. All differences are lessened if the comparison be limited to children, and still further lessened if also limited to cities. Thus, the illiteracy of non-Caucasians was 44.5%, of their children. 30.1%, and of such in cities of 25,000 inhabitants, 7.7%,
In the total population of 10 years of age and over the female sex is more illiterate than the male, but within the age-group 10 to 24 years the reverse is true. In 1890 females preponderated among illiterates only in the age-group 10 to 19 years. The excess of female illiteracy in the total population also decreased within the same period, from 20.3 to 108 illiterates in a thousand. The tendency is therefore clearly toward an ultimate higher literacy for females; a natural result where the two sexes enjoy equal facilities of schooling, and the females greater leisure. Among the whites attending school there was still in 1900 a slight excess of males; among the negro pupils females were very decidedly in excess. In all races there has been since 1890, throughout the country, a large increase in the proportion of girls among the pupils of each age-group; and this is particularly true of the group of 15 years and upwardthat is of the grammar school and high school age, in which girls were in 1900 decidedly preponderant. A similar tendency is marked iii college education.
Religious Bodies.According to the national census of religious bodies taken in 1906 there were then in the country 186 denominations represented by 212,230 organizations, 92.2% of which represented 164 bodies which in history and general character are identified more or less closely with the Protestant Reformation or its subsequent development. The Roman Catholic Church contributed 5.9% of the organizations. Among other denominations the Jewish congregations and the Latter Day Saints were the largest. The immigrant movement brings with it many new sects, as, for example, the Eastern. Orthodox churches (Russian, Servian, Syrian and Greek), which had practically no existence in 1890, the year of the last preceding census of religious bodies. But the growth of independent churches is most remarkable, having been sixfold since 1890.
The statistics of communicants or members are defective, and because of the different organization in this respect of different bcdies, notably of the Protestants and Roman Catholics, comparisons are more or less misleading. Disregarding, however, such incomparability, but excluding 15% of all Roman Catholics (for children under 9 years of age), the total number of church members was 32,936,445, of whom 61.6% were Protestants, 36.7% Roman Catholics and 1.7% members of other churches. The corresponding figures in 1890 were 680, 30-3 and 1.7%. For the reasons just given these figures do not accurately indicate the religious affiliations of the population of the United States. In this particular they very largely understate the number of Hebrews, whose communicants (0.3%) are heads of families only, and largely of the Protestants; whereas they represent practically the total Roman Catholic population above 9 years of age. In comparing the figures of 1890 with those of 1906 these cautions are not of force, since both census counts were taken by the same methods. The membership of the Protestant bodies increased in the interval 44-8%, while that of the Roman Catholic Church increased 93-5%. The immigration from Catholic countries could easily account for (though this does not prove that in fact it is the only cause of) this great increase of the Roman Catholic body.
Among the Protestants, the Mcthodists with 17.5% of the total membership, the Baptists with 17.2, the Lutherans with 64, the Presbyterians with 5.6 and the Disciples and Christians with 3~5 each of these bodies comprising more than a million members together include one-half of the total church membership of the country, and four-fifths (81.3%) of all Protestant members.
The Baptists and Methodists are much stronger in the South, relatively to other bodies, than elsewhere; the former constituting in the South Atlantic states 43~9 / of all church members, and in the South Central states 395%. Adding in the Methodists these proportions become 76-3 and 65-3%. The Lutherans are relativel~ strongest in the North Central division of the country (13.2%); the Presbyterians in the North Atlantic and Western divisions (6-0%); and the Disciples in the South Central division (6-f %). The Roman Catholics are strongest in the Western division and the North Atlantic division, with 49.2% in the former and 56.6% in the latter of all church members; their share in the North Central division is 36-9%. Thus the numerical superiority of the Baptists and Methodists in the two Southern divisions is complementary to that of the Roman Catholics in the other three divisions of the country. New York, Rhode Island, Massachusetts and New Hampshire in the eastern part of the country, Louisiana in the south, and New Mexico, Arizona, California and Montana in the western part are distinctively Roman Catholic states, with not less than 63% of these in the total church body. Racial elements are for the most part the explanation. So also the immigration of French Canadians and of Irish explains the fact that in every state of one-time Puritan New England the Roman Catholics were a majority over Protestants and all other churches. This was true in I89o of 12 states, while in one other the Roman Catholics held a plurality; in 1906 the corresponding figures were 16 and 20. The Protestant bodies are more widely and evenly distributed throughuut the country than are the Roman Catholics.
The total value of church property (almost in its entirety exempt from taxation) reported in 1906 was $1,257,575,867, of which $935,942,578 was reported for Protestant bodies, $292,638,786 for Roman Catholic bodies, and $28,994,502 for all other bodies.
Occupations.29,o73,233 persons 10 years or more of age nearly two-fifths (38-3%) of the countrys total population were engaged in gainful occupations in 1900. Occupations were reported first for free males in 1850, and sin.ce 1860 women workers have been separately reported. Five main occupation groups are covered by the census: (I) agriculture, (2) professional service, (3) domestic and personal service, (4) trade and transportation, (5) manufacture and mechanical pursuits. The percentage of all wage-earners engaged in these groups in 1900 was 357~ 4.3, 19.2, 164, and 24-4 respectively. Outside of these are the groups of mining and fishing.
Although manufactures have increased tremendously. of recent yearstheir products representing in 1905 a gross total of $14,802,147,087 as compared with $6,309,000,000 for those of farms (according to the U.S. Department of Agri cuiture)agriculture is still the predominant industry of the United States, employing nearly half of the workers, and probably giving subsistence to considerably more than half of the people of the country.
Turning to the factor of sex, it may be stated that the t umber of the gainfully employed in 1900 above give1~ included 8 / of all the men and boys, and 18-8% of all the women and gi in the country. The corresponding figures in 1880 were 78.7 and 4.7% The proportion of women workers is greatest in the North Atlantic group of states (22-1%) where they are engaged in manufacturing, and in the South (23.8) where negro women are engaged in agricultural operations. The percentage of such wage-earners is therefore increasing much more rapidly in the former region. But in all other parts of the country the increase is faster than in the South; since aside from agriculture, which has long been in a relatively stable condition, there is not by any means so strong a movement of women into professional services in city districts. The increase is universal. There is not a state that does not show it. The greatest increase for any section between 1880 and 1900 was that of the North Central division from 8-8 to 14-3%. Here too both factorsfarm-life, as in North Dakota, and manufacturing, as in illinoisshowed their plain influence.
Of all agricultural laborers 9.4%Were females in 1900 ~ in 1880); but in the South the proportion was much greaterI 6-5 in the South Atlantic and 14-9 in the South Central division. In professional service 34.2% (in 188o, 29.4) were females, the two northern sections showing the highest proportions. In the occupations of musicians and teachers of music, and of school-teachers and professors (which together account for seven-eighths of professional women) women preponderate. The same sex constituted only 37-5% (34.6 0/c, in 1880) of the wage-earners of the third group; the South also showing here, as is natural in view of its colored class, much the highest and the Wescern division of states much the lowest percentage. Women are in excess in the occupations of boarding and lodging house keepers, housekeepers, launderers, nurses and midwives, and servants and waiters. These account for almost all women in this group; servants and waitresses make up two-thirds of the total. Finally, in the fourth and fifth groups the percentage of women was 10-6 (3-4 in 1880) and 18-5 (16.7 in 1880). In manufactures the South Atlantic states show a higher percentage than the North Central, owing to the element of childlabour already indicated. In the third group women greatly preponderate in the occupation of stenographers and type-writers; and in those of book-keepers and accountants, clerks and copyists, packers and shippers, saleswomen (which is the largest class), and telegraph and telephone operators they have a large representation (13 to 34 ~ A great Variation exists in the proportion of the sexes employed in different manufacturing industries. Of dress-makers, milliners, seamstresses (which together niake up near half of the total in this occupation group) more than 96% are women. Of the makers of paper boxes, of shirts, collars and cuffs, of hosiery and knitting mill operatives, of glove-makers, silk mill operatives and book-binders they are more than half; so also of other textile workers, excluding wool and cotton mill operatives (these last the second largest group of women workers in manufactures), in which occupations males arc in a slight excess. The distribution of women wageearners in 1900 among the great occupation groups was as follows:
in agriculture, 18-4%; professional service, 8f %; domestic and personal service, 39,4%; trade and transportation, 9.4%; manufacturing and mechanical pursuits, 24-7%.
The proportion which children fo to 15 years of age engaged in gainful occupations bore to the whole number of such children was in 1880 24-4% for males, and 9.0% for females. Twenty years later the corresponding figures were 26f and I02%. In the North Atlantic and North Central states, notwithstanding their manufacturing industries, the proportions were much lower (17.1 and I 7O in 1900), and they increased very little in the period mentioned. In the Western group the increase was even less, and the total (10.9% in 1900) also. But in the South Atlantic and the South Central stateswhere agrictilture, mining and manufacturing have in recent decades become importantalthough the increase was very slight, the proportions were far above those of the other sections, both in 1880 and in 1900. In the former year the ratios were 40.2 and 41.5, in the latter 41-6 and 427%. In Alabama (70.8% in 1880), North and South Carolina, amid Arkansas the ratio exceeded 5o % in 1900.
National Wealth.Mulhall has estimated the aggregate wealth of the United States in 1790 at $620,000,000, assigning of this value $479,000,000 to lands and $141,000,000 to buildings and improvements. It is probable that this estimate is generous according to the values of that time. But even supposing $1,000,000,000 to be a juster estimate according to present-day values, it is probable that the increase of this since 1790 has been more than a hundredfold and since 1850 (since when such data have been gathered by the census) about fifteenfold. The value of farm property increased from $3,967,343,580 in 1850 to $20,439,901,164 in 1900. The gross value of manufactures rose in the same interval from $1,019,106,616 to $13,010,036,514; of farm products, from $2,212,540,927 in 1880 to $6,309,000,000 in 1900. The census estimate of the true value of property constituting the national wealth was limited in an enumeration of 1850 to taxable realty and privately held personalty; in 1900 it covered also exempt realty, government land, and corporation and ptiblic personalty. The estimate of the national wealth of 1850 was $7,I35,78o,228jj~ 1904 (made by the census office), $107,104,192,410. It may be added that the net ordinary revenue of the government was in 1850 $43,592,889, and in 1909 $662,324,445; that the value of imports rose from $7.48 ~er capita in 1850 to $14.47 in 1909; and of exports from $6.23 to $18.50. The public debt on the 1st of November 1909, less certificates and notes offset by cash in the Treasury, was $1,295,147,432o4.
In the colonial period there were beginnings in some lines of manufacturing, but the policy of the British government was generally hostile and the increase was insignificant. In the first decades after the establishment of independence the resources and energies of the nation were absorbed in the task of occupying the vacant spaces of a continent, and sub-, duing it to agriculture; and so long as land was so abundant that the spreading population easily sustained itself upon the fruits of the soil, and satisfied the tastes of a simple society with the products of neighborhood handicrafts, there was no incentive to any real development of a factory economy. This has been, for the most part, a development since the Civil War.
No attempt was made in the census enumerations of 1790 and 1800 to obtain statistics of manufactures. In 1810 Congress provided for such a report, but the results were so imperfect that there was never published any summary for the country, nor for any state. Nor were the data secured in 1820 and 1840 of much value. Since 1850, however, provision has been made on an ample scale for their collection, although the constant modifications of the schedules under which the statistics were arranged makes very difficult comparisons of the latest with the earlier censuses.
From 1850 to 1900 fairly full industrial statistics were gathered as a part of each decennial census. In 1905 was taken the first of a new series of special decennial censuses of manufactures, in which only true factoriesthat is, establishments producing standardized products intended for the general marketwere included, and mere neighborhood (local) establishments of the hand trades were excluded. Without corrections, therefore, the figures of earlier censuses are not comparable with those of the census of 1905. Thus of 512,254 establishments included in the reports of 1900, six-tenths, employing II ~2% of the total number of wage-earners and producing 123% of the total value of all manufactures, must be omitted as neighborhood establishments in order to make the following comparison of the results of the two enumerations of 1900 and 1905. The magnitude in 1905 of each of the leading items, and its increase since 1900, then appear as follows: number of factories, 216,262, increase 4.2%; capital invested, $12,686,265,673, increase 41.3% salaries, $574,761,231, increase 50.9%; total wages, $2,009,735,799, increase 29.9%; miscellaneous expenses, $1,455,019,473, increase 60-7%; cost of materials, $8,503,949,756, increase 29.3%; value of products, including custom work and repairing (in such factories), $14,802,147,087, being an increase of 29.7%. Of the last item $3,269,757,067 represented the value of the products of rural factories (that is, those in cities of under 8000 inhabitants). The increase of the different items during the five years was greater in every case in the rural than in the urban factories. There was a very slight decline in the number of child laborers both in city and country, their total number in 1905 being 159,899 and in 1900 161,276. The total wages paid to children under i6 years, however, which was in 1905 $27,988,207, increased both in the city and, especially, in the country, and was 13.9% greater in 1905 than five years earlier. In the same period there was an increase of 16.0% in the number and of 27.5% in the wages of women workers of 16 years (and upwards) of age.
Deducting from the total value of manufactured products in 1905 the cost of partially manufactured materials, including mill supplies; a net or true value of $9,821,205,387 remains. Partially manufactured articles imported for use in manufactures are not included. Deducting from this the cost of raw materials and adding the cost of mill supplies, the result$6,743,399,7f8
is the value added to materials by manufacturing processes.
The extent to which manufactures are controlled by large factories is shown by the fact that although in 1905 only II~2% of the total number reported products valued at $100,000 or over, these establishments controlled 81.5% of the capital, employed 7 ~6% of the wage earners, and produced 793% of the value of the products, of all establishments reported. 523% of the total number, employing 66.3% of all wage-earners, and producing 69.7% of the total product-value, were in urban centres.
Only six establishments in a thousand employed as many as 500 workers, and only two in a thousand employed as many as 1000 workers. Cotton mills are most numerous in the last class of establishments. The manufacture of lumber and timber gave employment to the largest total number of workers; and this industry, together with those of foundry and machine shops (including locomotives, stoves and furnaces), cotton goods (including small wares), railway car and repair shops, and iron and steel, were (in order) the five greatest employers of labor.
Measured by the gross value of products, wholesale slaughtering and meat packing was the most important industry in 1903. The products were valued at $801,757,137. In each of four other industries the products exceeded in value five hundred millions of dollars, namely, those of foundry and machine shops, flour and grist mills, iron and steel, and lumber and timber. In one other, cotton goods, the value was little less. These six industries contributed 27.2% of the value of all manufactured products. Both in 1905 and in 1900 the group of industries classed as of food and kindred products ranked first in the cost of materials used and the value of products; the group of iron and steel ranking first in capital and in wages paid; and textiles in the number of wage-earners employed.
The c-1n~e reltion of maniifnctiires i-n sarri,lfiire; rsflerterl in the fact that, of the raw materials used, 79.4% came from the farm. The remainder came from mines and quarries, 15.0%; forests, 5.2%; the sea, 0.4%.
Four statesNew York, Pennsylvania, Illinois and Massachusetts each manufactured in 1900 products valued at over $1,000,000,000; New York exceeding and Pennsylvania attaining almost twice that sum. The manufacture of some products is highly localized. Thus, of silk goods, worsteds, the products of blast furnaces, of rolling mills and steel works, glass, boots and shoes, hosiery and knit goods, slaughtering and meat products, agricultural implements, woollens, leather goods, cotton goods and paper and wood pulp, four leading states produced in each case from 88~5%, in the case of silk goods, to 58.6% in the case of pulp.
M. G. Mulhall (Industry and Weatlh of Nations, 1896) assigned fourth place to the United States in 1880 and first place in 1894 in the value of manufactured products,, as compared with other countries. Paul Leroy-Beaulieu (Les tats- Unis au XX Sicle, Paris, 1904) would assign primacy to the United States as far back as 1885. Since the English board of trade estimated the exports of British manufactured goods at from 17 to 20% of the industrial output of the United Kingdom in 1902, this would indicate a manufactured product hardly two-thirds as great as that of the true factory establishments of the United States in 1900. But exact data for comparison do not exist for other countries than the United States. In the production of pig iron, the share of the United States seems to have been in 1850 about one-eighth and that of Great Britain onehalf of the worlds product; while in 1903 the respective shares were 38.8 and 19.3%; and Germanys also slightly exceeded the British output. In the manufacture of textiles the United States holds the second place, after Great Britain; decidedly second in cottons, a close competitor with Great Britain and France in woollens, and with France in silks. In the manufacture of food products the United States holds a lead that is the natural result of immense advantages in the production of raw materials. No other country produces half so much of leather. In the dependent industry of boots and shoes her position is commanding. These facts give an idea of the rank of the country among the manufacturing countries of the world. The basis of this position is generally considered to be, partly, immense natural resources available as materials, and, partly, an immense home market.
Minerals.In 1619 the erection of works for smelting the ores of iron was begun at Falling Creek, near Jamestown, Va., and iron appears to have been made in 1620; but the enterprise was stopped by a general massacre of the settlers in that region. In 1643 the business of smelting and manufacturing iron was begun at Lynn, Mass., where it was successfully carried on, at least up to 1671, furnishing most of the iron used in the colony. From the middle of the 17th century the smelting of this metal began to be of importance in Massachusetts Bay and vicinity, and by the close of the century there had been a large number of ironworks established in that colony, which, for a century after its settlement, was the chief seat of the iron manufacture in America, bog ores, taken from the bottom of the ponds, being chiefly used. Early in the I 8th century the industry began to extend over New England and into New Jersey, the German bloomery forge being employed for reducing the ore directly to bar iron, and by the middle of that century it had taken a pretty firm hold in the Atlantic colonies. About 1789 there were fourteen furnaces and thirty-four forges in operation in Pennsylvania. Before the separation of the colonies from the mother country, the mahufacture of iron had been extended through all of them, with the possible exception of Georgia. As early as 1718 iron (both pig and bar) began to be sent to Great Britain, the only country to which the export was permitted, the annual amount between 1730 and 1775 varying ordinarily between 2000 and 3000 tons, but in one year (1771) rising to between 7000 and 8000 tons.
The first metal other than iron mined by whites within the territory of the United States was lead, the discovery of which on the American continent was recorded in 1621. The first English settlers on the Atlantic bartered lead of domestic origin with the Indians in the 17th century, and so did the French in the upper Mississippi Valley. The ore of the metal occurring in the Mississippi basingalena----is scattered widely and in large quantities, and being easily smelted by the roughest possible methods was much used at an early date. In the second half of the 18th century, during the period of French and Spanish domination in the valley, lead was a common medium of exchange, but no real mining development took place. Copper was the next metal to be mined, so far as is known. The first company began work about 1709, at Simsbury, Conn. The ore obtained there and in New Jersey seems to have been mostly shipped to England. A few years later attempts were made to work mines of lead and cobalt in Connecticut and Massachusetts.
The first mining excitement of the United States dates back to the discovery of gold by the whites in the Southern states, along the eastern border of the Appalachian range, in Virginia, and in North and South Carolina. The existence ~of gold in that region had been long known to the aboriginal inhabitants, but no attention was paid to this by the whites, until about the beginning of the soth renf,irv, when n,ipvpts were found, one of which weighed 28 lb.
From 1824 the search for gold continued, and by 1829 the business had become important, and was attended with no little excitement. In 1833 and 1834 the amount annually obtained had risen to fully a million of dollars. A rapid development of the lead mines of the West, both in Missouri and on the Upper Mississippi in the region where Iowa, Wisconsin and Illinois adjoin one another, took place during the first quarter of the I9th century, and as early as 1826 or 1827 the amount of this metal obtained had risen to nearly 10,000 tons a year. By this time the making of iron had also become important, the production for 1828 being estimated at 130,000 tons.
In 1820 the first cargo of anthracite coal was shipped to Philadelphia. From 1830 the increase in the production was very rapid, and in 1841 the annual shipments from the Pennsylvania anthracite region had nearly reached 1,000,000 tons, the output of iron at that time being estimated at about 300,000 tons. The development of the coal and iron interests, and the increasing importance of the gold product of the Appalachian auriferous belt, and also of the lead product of the Mississippi Valley, led to a more general and decided interest in geology and mining; and about 1830 geological surveys of several of the Atlantic states were begun, and more systematic explorations for the ores of the metals, as well as for coal, were carried on over all parts of the country then open to settlement. An important step was taken in 1844, when a cession of the region on the south shore of Lake Superior was obtained from the Chippewa Indians. Here explorations for copper immediately began, and for the first time in the United States the business of mining for the metals began to be developed on an extensive scale, with suitable appliances, and with financial success. An event of still greater importance took place almost immediately after the value of the copper region in question had been fully ascertained. This was the demonstration of the fact that gold existed in large quantities along the western slope of the Sierra Nevada of California. In five years from the discovery of gold at Coloma on the American river, the yield from the auriferous belt of the Sierra Nevada had risen to an amount estimated at between sixty-five and seventy millions of dollars a year, or five times as much as the total production of this metal throughout the world at the beginning of the century.
The following details show the development of the mineral resources of the country at the middle of the 19th century. In 1850
the shipments of anthracite amounted to nearly 3,500,000 ~ L1~ tons; those of Cumberland or semi-bituminous coal were Industries about 200,000 tons. The yearly production of pig iron a ou had risen to between 500,000 and 600,ooo tons. The annual yield of gold in the Appalachian belt had fallen off to about $500,000 in value, that of California had risen to $36,000,000, and was rapidly approaching the epoch of its culmination (1851I 853). No silver was obtained in the country, except what was separated from the native gold, that mined in California containing usually from 8 to 10% of the less valuable metal. The ore of mercury had been discovered in California before the epoch of the gold excitement, and was being extensively worked, the yield in the year1850-1851being nearly 2,000,000 lb. At this time the copper mines of Lake Superior were being successfully developed, and nearly 6oo tons of metallic copper were produced in 1850. At many points in the Appalachian belt attempts had been made to work mines of copper and lead, but with no considerable success, About the middle of the century extensive works were erected at Newark, New Jersey, fo1~ the manufacture of the oxide of zinc for paint; about 1100 tons were produced in 1852. The extent and value of the deposits of zinc ore in the Saucon Valley, Pennsylvania, had also just become known in 1850. The lead production of the Missouri mines had for some years been nearly stationary, or had declined slightly from its former importance; while that of the upper Mississippi region, which in the years just previous to 1850 had risen to from 20,000 to 25,000 tons a year, was declining, having in 1850 sunk to less than 18,000 tons.
At the end of the century, in only fifty years, the United States had secured an easy first place among the mineral-producing countries of the world. It held primacy, with a large margin, in the yield of coal, iron, lead and copper, the minerals most important in manufactures; in gold its output ini~usifrIcs was second only to that ,of South Africa (though practically equalled by that of Australia); and in silver to that of Mexico. Although the data are in general incomplete upon which might be based a comparison of the relative standing of different countries in the production of minerals of lesser importance than those just mentioned, it was estimated by M. G. Mulhall (Industries and Wealth of Nations, edition of 1896, pp. 3435) that Great Britain then produced approximately one-third, the United States one-third, and all other countries collectively one-third of the minerals of the world in weight.
The leading products, as reported by the Geological Survey for 1907, were as follows: coal, $614,798,898 (85,604,312 tons of anthracite coal, 394.759,112 of bituminous); petroleum, $120,106,749; natural gas, ~54,222,399; iron ore, $131,996,147 (pig iron, $529,958,000); copper, refined, $173,799,300; gold, coinage value, $90,435,700; buii~..ing-stone, $71,105,805; silver, commercial value, ~272OO,700: lean. reftn~I ~2~1o7.co6~ and zinc. r~6ned. ~,6 AOl OlO
The North Atlantic and the North Central census groups of states (that is, the territory east of the Mississippi and north of the Ohio rivers, and north of Maryland) produced two-thirds of the total output. Pennsylvania, Ohio, Illinois, West Virginia, California, Colorado, Montana, Michigan, New York and Missouri were the ten states of greatest absolute production in 1907. The rank relative to area or population is of course different. Those which, according to the bureau of the census, produced $1000 or over per sq. m. in 1902 were Pennsylvania, Ohio and West Virginia; $500 to $1000, Illinois, Michigan, Indiana, Vermont and Massachusetts. Seventeen states produced from $ioo to $500 per sq. m.
The total mineral output for the decade1899-1908according to the United States Geological Survey was as follows:
Value of Value of Year. Total Value Non-metallic Metallic of Products. Products. Products.
1908 1,595,670,186 1,045,497,070 549,923,116
1907 2,071,607,964 1,167,705,720 9c~,8o2,244
1906 1,902,517,565 1,016,206,709 886,110,856
1905 1,623,928,720 921,075,619 702,453,101
1904 1,361,067,554 859,383,604 501,099,950
1903 1,491,928,980 793,962,609 624,3 i8,008
1902 1,323,102,717 617,251,154 642,258,584
1901 1,141,972 309 567,318,592 518,266,259
1900 1,107,020,352 512,195,262 550,425,286
1899 1,014,355,705 446,090,251 525,472,981
The vastly greater part of mineral products are used in manufactures within the United States, and only an insignificant part (for example, 247% in 1902) is exported in the crude form.
Coal exists in the United States in large quantity in each of its important varieties: anthracite, or hard coal; bituminous, or soft coal; and lignite; and in various intermediate and c al special grades. Geologically the anthracite and bituminous coals mainly belong to the same formation, the Carboniferous, and this is especially true of the better qualities; though it is stated by the United States Geological Survey that the geQlogic age of the coal beds ranges from Carboniferous in the Appalachian and Mississippi Valley provinces to Miocene (Tertiary) on the Pacific coast, and that the quality of the coal varies only to a very uncertain degree with the geologic age. The following estimates rest upon the same authority: (I) total area underlaid by coal measures, 496,776 sq. m., of which 250,531 are credited to anthracite and bituminous, 97,636 to sub-bituminous and 148,609 to lignite; (2) total original coal supply of the country, 3,076,204,000,000 short tons, including 21,000,000,000 tons of anthracite in Pennsylvania, and small amounts elsewhere (semi-anthracite and semi-bituminous), 650,157,000,000 tons of sub-bituminous and 743,590,000,000 tons of lignite; (3) easily accessible coal still available, 1,992,979,000,000 tons; (4) available coal accessible with difficulty, f,153,225,000,000 tons.
The total production of coal from 1814 (the year in which anthracite was first mined in Pennsylvania) to 1908 amounted to 7,280,940,265 tons, which represented an exhaustionadding 50% for waste in mining and preparationof 11,870,049,900, or four-tenths of I % of the supposed original supply.
In 1820 the total production was only 3450 tons In 1850 it was already more than 7,000,000. And since then, while the population increased 230% from 1850 to 1900, the production of coal increased 4,084%. At the same time that the per capita consumption thus rose in 1907 to 5~6 tons, the waste was estimated by the National Conservation Commission at 3~0 tons per capita. This waste, however, is decreasing, the coal abandoned in the mine having averaged, in the beginning of mining, two or three times the amount taken out; and the chief part of the remaining waste is in imperfect combustion in furnaces and fire-boxes. Thus, notwithstanding the fact that the supposed supply still available at the close of 1908 was 7369 times the production of that year, and 4913 times the exhaustion such production represented, so extraordinary has been the increased consumption of the country that, in the opinion of the Geological Survey (1907), if the rate of increase that has held for the last fifty years is maintained, the supply of easily available coal will be exhausted before the middle of the next century (A.o. 2050).
In 1870 both Great Britain and Germany exceeded the United States in the production of coal. Germany was passed in 1871
(definitively in 1877); Great Britain in 1899. Since 1901 the United States has produced more than one-third of the worlds output.
Coal was produced in 1908 in 30 states out of the 46 of the Union; and occurs also in enormous quantities in Alaska; 690,438 men were employed in this year in the coal mines. Pennsylvania (117,179,527 tons of bituminous and 83,268,754 of anthracite), Illinois (47,659,690), West Virginia (41,897,843), Ohio (26,270,639), Indiana (12,314,890) and Alabama (11,604,593) were the states of greatest production. The production of each was greater still in 1907.
The total oiitnijt amounted to zLIc.8a2.6o2 short tons, valued at $532 3 i4,1 17 in 1908 and to 480,363,424t0ns, valued at $614,798,898 in 1909 Pennsylvania produced three-fourths of the total output of the country in 1860, and since 1900 slightly less than one-half. Up to 1870 there was more anthracite mined in Pennsylvania than bituminous in the whole country, but since that year the production of the latter has become vastly the greater, the totals in 1907, in which year each stood at its maximum, being 83,268,754 and 332,573,944 tons respectively.
Inasmuch as the present production is not considered locally and with more or less justiceas at all indicative of the wealth in coal of the respective states, it may be said that according to estimates of the Geological Survey the following states are credited with the deposits indicated of true bituminous coal, including local admixtures of anthracite, the figures being millions of short tons:
Colorado, 296,272; Illinois, 240,000; \Vest Virginia, 231,000; Utah, 196,408; Pennsylvania, 112,574; Kentucky, 104,028; OhiO, 86,028; Alabama, 68,903; Indiana, 44,169; Missouri, 40,ooo; New Mexico, 30,805, Tennessee, 25,665; Virginia. 21,600; Michigan, 12,000; ~Iaryland, 8,044; Texas, 8,000; Kansas, 7,022; and Montana, 5,000; with lesser deposits in other states. At the same time there are estimated deposits of sub-bituminous coal, isolated or mixed with bituminous, amounting to 75,498 millions of tons in Colorado (which is probably the richest coal area of the country); and in other states as follows: Wyoming, 423,952 millions of tons; New Mexico, I3,975; Washington, 20,000; Montana, 18,560; California and Oregon, 1000 each; and lesser amounts elsewhere. Finally, of true lignite beds, or of lignite mix d with sub-bituminous qualities, the states of North Dakota, Montana, Texas and South Dakota are credited with deposits of 500,000; 279,500; 23,000; and 10,000 millions of tons respectively. But it is to be remembered that the amount and the fuel value of both the lignite and, to a lesser degree, the sub-bituminjus coals, is uncertain to a high degree.
Petroleum, according to the report of the National Conservation Commission in 1908, was then the sixth largest contributor to the Petrol nations mineral wealth, furnishing about one-sixteenth eum. of the total. Oil was produced in 1908 in sixteen states., This productive area is divided by the United States Geological Survey into six fields (in addition to some scattering states) with reference to the quality of oil that they produce, such quality determining their uses. The Appalachian field (Pennsylvania, New York, Ohio, West Virginia and Tennessee) produces oil rich in paraffin, practically free from sulphur and asphalt, and yielding the largest percentage of gasoline and illuminating oils. This is the highest grade crude oil produced in the world. The California field produces oil characterized by much asphalt and little or no paraffin, and low in volatile constituents. The Lima (Ohio)-Indiana, the Illinois, the Mid-Continent (Kansas, Oklahoma and northern Texas) and the Gulf (Texas and Louisiana) fields produce oils containing more or less of sulphur and asphalt between the extremes of the two other fields just mentioned. The geological conditions of the different fields, and the details of the composition of the oils yielded, are exceedingly varied, and their study has been little more than begun In 1859 when the total output of the country is supposed to have been only 2000 barrels of oil, production was confined to Pennsylvania and New York. Ohio, West Virginia and California appeared as producers in 1876, Kentucky and Tennessee in 1883, Colorado in 1887. Indiana in 1889, along with Illinois, Kansas, Texas and Missouri, Oklahoma in 1891, Wyoming in 1894, and, lastly, Louisiana in 1902. From 1859 to 1876 the Appalachian field yielded IoO% of the total output of the country; in 1908 its share had fallen to 13.9%. Ia the same period of 50 years the yearly output rose from 2000 to 179,572,479 barrels (134,717,580 in 1905) and to a grand total of 1,986,180,942 barrels, worth $1,784,583,943, or more than half the value of all the gold, and more than the commercial value of all the silver produced in the country since 1792. The production in 1908 exceeded in value the output of both metals. Deducing from the figures of production since 1859 an equation of increase, one finds that in each nine years as much oil has been produced as in all preceding years together, and in recent years the factor of increase has been higher. So rapid has been the extension of the yielding areas, so diverse the fate of many fields, so shifting their relative rank in output, that the otitlook from year to year as regards all these elements is too uncertain to admit of definite statements respecting the relative importance of the five fields already mentioned The total output of these, it may be stated, from 1901 to 1908uniting the yield of the Illinois to the Lima-Indiana field (since their statistics were long so united, until their industrial differences became apparent), and adding a sixth division for the production of scattered areas of productionwas as follows:
Appalachian, 235,999,859; Lima-Indiana-Illinois, 219,609,347; Mid- Continent, 136,148,892; Gulf, 159,520,306; California, 27,931,687; and others, 3,367,666; the leading producers in1907-1908being the Mid-Continent and the California areas.
The worlds output of oil was trebled between 1885 and 1895, and quadrupled between 1885 and 1900. In this increase the United States had the largest share. So recently as 1902 the output of the United States was little greater than that of Kussia (the two yielding 91.4% of the worlds product), but this advantage has since then been greatly increased, so that the one has produced 63.1 and the other 21.8% of the total output of the world. In 1908 the Geological Survey issued a preliminary map of the then known areas productive of oil and natural gas in the United States, estimating the extent of the former at 8850 and of the latter at 9365 sq. m. The supply of oil in this area was estimated at from 15,000,000,000 to 20,000,000,000 barrels; and the National Conservation Commission of 1908 expressed the opinion that in view of the rapid increase of production and the enormous loss through misuse the supply cannot be expected to last beyond the middle of this century.
Natural gas, as a source of light and for metallurgical purposes, became important in the mid-eighties. In recent years its use for industrial purposes has lessened, and for domestic pdr-Naturaj Gas poses increased. The existence of outflows or springs of gas in the region west of the Alleghanies had long been known, and much gas was used for illuminating purposes in Fredonia, New York, as early as 1821. Such gas is a more or less general concomitant of oil all through the petroleum-bearing areas of the country. The total output of the country rose from a value of $215,000 ifl 1882 to one of $54,640,374 ifl 1908, with several fluctuations up and down in that interval. Pennsylvania, with a product valued at $155,620,395 from 1899 to 1908, West Virginia with $84,955,496, Ohio with $48,172,450 and Indiana with $46,141,553 were the greatest producers of the Union.
The National Conservation Commission in 1908 estimated the area of the known gas fields of the country at 9000 sq. hi.; the portion of their yield in 1907 that was utilized at 400,000,000,000 cub. ft.; and the Waste at an equal amountmore than 1,000,000,000 of cub. ft. daily, or enough to supply all the cities in the United States of above 100,000 population.
Of other non-metallic mineral substances, apart from coal, petroleum and natural gas, little need be said in detail. Stone is of the greatest actual importance, the value of the quarry output, including some prepared or manufactured product, such as dressed and crushed stone, averaging $65,152,312 annually in 1904-1908.
Limestone is by far the largest element, and with granite makes up two-thirds of the total value. Vermont, Pennsylvania and New York are the leading producers. In this, as in other cases, actual product may indicate little regarding potential resources, and still less regarding the distribution of these throughout the Union. Glass and other sands and gravel ($13,270,032), lime ($11,091,186), phosphate rock ($10,653,558), salt ($7,553,632), natural mineral waters ($7,287,269), sulphur ($6,668,215, almost wholly from Louisiana), slate ($6,316,8 I7), gypsum ($4,138,560), clay ($2,599,986), asphalt ($1,888,881), talc and soapstone ($1,401,222), borax ($975,000, all from California), and pyrite ($857,113) were the next most important products in 1908. It may be noted that the output in almost every item of mineral production was considerably greater in 1907 than in 1908, and the isolated figures of the latter year are of little interest apart from showing in a general way the relative commercial importance of the products named. In the yield of gypsum, phosphate rock and salt the United States leads the world. In sulphur it is a close second to Sicily. Phosphate rock is heavily exported, and in the opinion of the National Conservation Commission of 1908 the supply cannot long satisfy the increasing demand for export, which constitutes a waste of a precious natural resource. Other minerals whose production may be found stated in detail in the annual volume on Mineral Resources of the United States Geological Survey are: natural pigments, felspar, white mica, graphite, fluorspar, arsenic, quartz, barytes, bromine. Some dozens of varieties of precious stones occur widely. Of building-stone, clay, cement, lime, sand and salt, the countrys supply was estimated by the National Conservation Commission of 1908 to be ample.
In 1907 iron ore was mined for blast-furnace use in twenty-nine states only, but the ore occurs in almost every state of the Union. As nearly as can be estimated from imperfect statistics, frirn the total ore production of the country rose steadily from 2,873,400 long tons in, 1860 to 51,720,619 tons in 1907. The United States became practically independent of foreign ore imports during the decade 1870 to 1879. The iron-producing area of the country may be divided, with regard to natural geographic, historic and trade considerations, into four districts: (1) the Lake Superior district, embracing the states of Minnesota, Michigan and Wisconsin; (2) the southern district, embracing the triangle tipped by Texas, Maryland and Georgia; (3) the northern district, embracing the triangle tipped by Ohio, New Jersey and Massachusetts, plus the states of Iowa and Missouri; (4) the western district, which includes the states of the Rocky Mountain region and Pacific coast. Of these districts the Lake Superior regionwhich embraces the Marquette range (opened in 1854), the Menominee (1872), the Gogebic (1884), the Vermilion (1884) and the Mesabi (1892)first attracted exploration about 1844, when the copper deposits of the same region were opened, and produced from 1854 to 1908 a total of 1/210,239,551 long tons, of which 341,036,883 were mined in the period 1889-1908. From the Mesabi range alone, opened in 1892, no less than 168,143,661 long toas were taken up to 1908. The share of the whole district for some years past has been practically four-fifths of the total output of the country; and together with the yield of the southern district, more than 90%. Minnesota alone produces more than half of the same total, having multiplied her product since 1889 by more than 33 times. Michigan held first place in output until 1901. Alabama is the third gre