Ceraunius Tholus is a volcano on Mars located in the Tharsis quadrangle at 24.2 degrees north latitude and 97.4 degrees west longitude and it is a part of Uranius group of volcanoes. It is 130 km across, 5.5 km high and is named after a classical albedo feature name.
It is generally believed to be a basaltic shield with the lower
part buried beneath plain forming lavas. Earlier interpretations
suggested that it is a stratovolcano. The
slopes on Ceraunius Tholus are quite steep with an average slope of
8° with many radial erosion channels and pitted valleys extending
from just below the rim of the caldera toward the base of the volcano.
Interesting features on Ceraunius Tholus are three large canyons at
the northwest ﬂank of Ceraunius Tholus which are up to 2.5 km wide
and 300 m deep. The biggest of these three also appears to be the
youngest and protrude from the lowest point of the volcanic caldera
and ends at the interesting Rahe crater (an oblique impact crater
with measures of 35 × 18 km), just north from the volcano where it
formed a depositional fan. Its origin is still debatable and there
are four main models proposed: ﬂuvial action, volcanic flows,
valley being a lava channel or some combination of previously
The caldera of Ceranius Tholus is also dotted with many collapse pits which are distinct from impact craters as the have no rim and vary in concentration across caldera. Ceraunius Tholus is probably late Hesperian in age.
Some scientists believe that glaciers exist on many of the volcanoes in Tharsis including Olympus Mons, Ascraeus Mons, and Pavonis Mons.  Ceraunius Tholus may have even had its glaciers melt to form some temporary lakes in the past. The shape of the Ceraunius Tholus caldera suggests that in the past meltwater would also accumulate in a caldera lake. 
Tharsis is a land of great volcanoes. Olympus Mons is the tallest known volcano. Ascraeus Mons and Pavonis Mons are at least 200 miles across and are over six miles above the plateau that they sit on. Then, the plateau is three to four miles above the zero altitude of Mars.
Ceraunius Tholus Channel, as seen by HiRISE. The summit crater of Ceraunius Tholus is just to the right of this picture. Click on image to see dark slope streaks. The scale bar is 1000 meters long.