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Lateral moraine on a glacier joining the Gorner Glacier, Zermatt,
Switzerland. The moraine is the high bank of debris in the top left
hand quarter of the picture. For more explanation, click on the
picture.
Glaciology (from Middle French dialect
(Franco-Provençal): glace, "ice"; or Latin: glacies, "frost, ice"; and Greek:
λόγος, logos, "speech"
lit. "study of ice") is the study of glaciers, or more generally ice and natural phenomena that involve ice.
Glaciology is an interdisciplinary earth science that integrates geophysics, geology, physical
geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on humans adds
the fields of human geography and anthropology. The
presence of ice on Mars and Europa brings in an
extraterrestrial component to the field.
Overview
Areas of study within glaciology include glacial history and the
reconstruction of past glaciation. A glaciologist is a person who
studies glaciers. Glaciology is one of the key areas of polar
research. A glacier is an extended mass of ice formed from snow
falling and accumulating over the years and moving very slowly,
either descending from high mountains, as in valley glaciers, or
moving outward from centers of accumulation, as in continental
glaciers.
Types
There are two general categories of glaciation which
glaciologists distinguish: alpine glaciation,
accumulations or "rivers of ice" confined to valleys; and
continental glaciation, unrestricted accumulations which
once covered much of the northern continents.
- Alpine - ice flows down the valleys of mountainous areas and
forms a tongue of ice moving towards the plains below. Alpine
glaciers tend to make the topography more rugged, by adding and
improving the scale of existing features such as large ravines
called cirques and
ridges where the rims of two cirques meet called arêtes.
- Continental - an ice sheet found today, only in high latitudes
(Greenland/Antarctica), thousands of
square kilometers in area and thousands of meters thick. These tend
to smooth out the landscapes.
Zones of
glaciers
- Accumulation, where the formation of ice is faster than its
removal.
- Wastage or Ablation, where the sum of melting and evaporation
(sublimation) is greater than the amount of snow added each
year.
Movement
- Ablation
- wastage of the glacier through sublimation, ice melting and
iceberg calving.
- Ablation
zone
- Area of a glacier in which the annual loss of ice through
ablation exceeds the annual gain from precipitation.
- Arête
- an acute ridge of rock where two cirques abut.
- Bergshrund
- crevasse formed near the head of a glacier, where the mass of
ice has rotated, sheared and torn itself apart in the manner of a
geological fault.
- Cirque, corrie or
cwm
- bowl shaped depression excavated by the source of a
glacier.
- Creep
- adjustment to stress at a molecular level.
- Flow
- movement (of ice) in a constant direction.
- Fracture
- brittle failure (breaking of ice) under the stress raised when
movement is too rapid to be accommodated by creep. It happens for
example, as the central part of a glacier movinges faster than the
edges.
- Horn
- spire of rock formed by the headward erosion of a ring of cirques
around a single mountain. It is an extreme case of an arête.
- Plucking/Quarrying
- where the adhesion of
the ice to the rock is stronger than the cohesion of the rock, part of the rock leaves
with the flowing ice.
- Tarn
- a lake formed in the bottom of a cirque when its glacier has
melted.
- Tunnel
valley
- The tunnel is that formed by hydraulic erosion of ice and rock
below an ice sheet margin. The tunnel valley is what remains of it
in the underlying rock when the ice sheet has melted.
Glacial
deposits
Stratified
- Outwash sand/gravel
- from front of glaciers, found on a plain
- Kettles
- block of stagnant ice leaves a depression or pit
- Eskers
- steep sided ridges of gravel/sand, possibly caused by streams
running under stagnant ice
- Kames
- stratified drift builds up low steep hills
- Varves
- alternating thin sedimentary beds (coarse and fine) of a proglacial
lake. Summer conditions deposit more and coarser material and
those of the winter, less and finer.
Unstratified
- Till-unsorted
- (glacial flour to boulders) deposited by receding/advancing
glaciers, forming moraines, and drumlins
- Moraines
- (Terminal) material deposited at the end; (Ground) material
deposited as glacier melts; (lateral) material deposited along the
sides.
- Drumlins
- smooth elongated hills composed of till.
- Ribbed moraines
- large subglacial elongated hills transverse to former ice
flow.
See also
References
- Benn, Douglas I. and David J. A. Evans. Glaciers and
Glaciation. London;
Arnold, 1998. ISBN 0-340-58431-9
- Greve, Ralf and Heinz Blatter. Dynamics of Ice Sheets and
Glaciers. Berlin etc.; Springer, 2009. ISBN
978-3-642-03414-5
- Hambrey, Michael and Jürg Alean. Glaciers. 2nd ed. Cambridge and New York; Cambridge University Press,
2004. ISBN 0-521-82808-2
- Hooke, Roger LeB. Principles of Glacier Mechanics. 2nd
ed. Cambridge and New York; Cambridge University Press, 2005. ISBN
0-521-54416-5
- Knight, Peter G. Glaciers. Cheltenham; Nelson Thornes, 1999. ISBN
0-7487-4000-7
- Paterson, W. Stanley B. The Physics of Glaciers. 3rd
ed. Oxford etc.; Pergamon
Press, 1994. ISBN 0-08-037944-3
- van der Veen, Cornelis J. Fundamentals of Glacier
Dynamics. Rotterdam; A. A. Balkema, 1999. ISBN
90-5410-471-6
External
links
- International Glaciological Society (IGS)
- International Association of
Cryospheric Sciences (IACS)
- Snow, Ice, and Permafrost
Group, University of Alaska Fairbanks
- Arctic and Alpine Research Group, University of
Alberta
- Glaciers online
- World Data Centre for Glaciology, Cambridge,
UK
- National Snow and Ice Data Center, Boulder,
Colorado
- Global Land Ice Measurements from Space,
USGS
- North Cascade Glacier Climate
Project
- Centre for Glaciology, University of Wales
- Caltech Glaciology Group
- Glaciology Group, University
of Copenhagen
- Institute of Low Temperature
Science, Sapporo
- National Institute of Polar Research, Tokyo
- Glaciology Group, University
of Washington
- Glaciology Laboratory, Universidad de Chile-Centro
de Estudios Científicos, Valdivia
- Russian Geographical Society (Moscow Centre) -
Glaciology Commission
- Institute of Meteorology and
Geophysics, Univ. of Innsbruck, Austria.
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