Cirque Floor Geology

Cirques are bowl shaped amphitheater like depressions that glaciers carve into mountains and valley sidewalls at high elevations.

Cirque floor geology.

Cirques subjected to seasonal melting often form small lakes. Chapman and hall 193 piccadilly oclc 1561924. Corrie combe cwm 1855 robert browning childe roland to the dark tower came in men and women london. Author s edition boston mass.

In early summer it opens exposing the rock at its base to diurnal. Once formed glaciers widen and deepen cirques by subglacial abrasion and quarrying of the hollow floor and lower headwall 3 see diagram below. True cirque growth only occurs once the thickness of snow patches increases to a point at which glacier ice can form by compaction. The floor of the cirque ends up bowl shaped as it is the complex convergence zone of combining ice flows from multiple directions and their accompanying rock burdens.

A cirque experiences greater erosion because of the accompanying rock burdens which may also over deepen the level of a cirque. Circle amphitheatre shaped basin with precipitous walls at the head of a glacial valley it generally results from erosion beneath the bergschrund of a glacier a bergschrund is a large crevasse that lies a short distance from the exposed rock walls and separates the stationary from the moving ice. Hence it experiences somewhat greater erosion forces and is most often overdeepened below the level of the cirque s low side outlet stage and its down slope backstage valley. Often the glaciers flow up and over the lip of the cirque as gravity drives them downslope.

Elias national park alaska sits in a classic bowl shaped cirque. The granite creek tarn wrangell st.