EARTHSC 1G03 Lecture 37: EARTHSC 1G03 - Lecture 37 (Glaciers)
19 Apr 2017
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Document Summary
Temperature low enough to retain snow year round: high latitude and altitude. Sufficient snow some polar climates are very dry, so glaciers do not develop. Canada was almost entirely covered by glaciers during the last ice age topography was carved by this event. Mountain glacier: in mountainous areas where snow doesn"t melt in the summer. Continental glacier: large, continental-scale feature flowing out from the centre. Glacial budget depends on snow input (accumulation) and ice loss due to melting and evaporation (ablation): accumulation takes place above the snowline, ablation takes place below the snowline. An advancing glacier occurs when the zone of accumulation increases. A retreating glacier occurs when the zone of accumulation decreases: note: ice molecules continue to move down the slope at all times due to gravity. Flow depends on response of ice to stress: top of ice fractures (brittle) and crevasses form, lower zone flows (ductile, at terminus, glide planes stack up like thrust faults.
