24 Page 25 BEHAVIOR OF A GLACIER (ABLATION VS ACCUMULATION) Regardless of the glacial budget condition, glacial ice continues to move forward even though the glacier as a whole may be stagnant or retreating Flow of glaciers based on the budget: - downwards in the zone of accumulation - lateral at the equilibrium line - upwards in the zone of ablation 25 Page 26 WORK DONE BY GLACIERS - glaciers modify the landscape extensively - produces landscapes that are unique to glaciation 1) Glacial Erosion 2) Glacial Transportation 3) Glacial Deposition 26 Page 27 WORK DONE BY GLACIERS 1) Glacial Erosion Plucking - breaking, lifting and removal of fragments of bedrock and sediments by ice (frost action) Abrasion - the scouring, smoothing or polishing action of materials embedded in the ice against the bedrock floor (sandpaper action)&#9;&#9; 27 Page 28 WORK DONE BY GLACIERS Controls on glacial erosion 1) the rate of glacial movement 2) the thickness of the ice 3) the shape, size, abundance, and hardness of the rock materials in the ice 4) the erodibility of the surface beneath the ice 25 Page 29 WORK DONE BY GLACIERS Erosional Features (Valley or Alpine Glaciers) 1) &quot;U&quot;-shaped glacial troughs as contrasted to &quot;V&quot;-shaped stream valleys (glaciers widens, deepens and straightens stream valleys) - type of valleys - main glacial trough and hanging valleys 29 Page 30 WORK DONE BY GLACIERS Erosional Features (Valley or Alpine Glaciers) 2) Truncated spur - irregular shaped cliff caused by removal of meanders 3) Cirque - a steep-sided, rounded bowl-shaped depression carved into a mountain wall at the head of a valley glacier 30 Page 31 WORK DONE BY GLACIERS Erosional Features (Valley or Alpine Glaciers) 4) Arete - a knife-edge peak formed by sideways erosion of two cirque glaciers 5) Horn - a pyramid-like peak at summits formed by headwards erosion of several coalescing cirques 6) Col - passage or gap formed by back-to-back erosion of cirques
(Col - passage or gap; formed; by back-to-back erosion of cirques) (glacial ice; to move; forward) (landscapes; are; unique to glaciation 1) (materials; embedded; in the ice against the bedrock floor) (a knife-edge peak; formed; by sideways) (glaciers; straightens; stream valleys) (the scouring; smoothing; ) (the glacier as a whole; retreating; Flow of glaciers) (summits; formed; by headwards erosion of several coalescing cirques) (a steep-sided, rounded bowl-shaped depression; carved; into a mountain wall at the head of a valley) (glaciers; widens; ) (25 Page 26 WORK DONE BY GLACIERS - glaciers; modify; the landscape) (spur - irregular shaped cliff; caused; by removal of meanders 3)
Col - passage or gap glacial ice landscapes materials a knife-edge peak glaciers the scouring the glacier as a whole summits a steep-sided, rounded bowl-shaped depression glaciers 25 Page 26 WORK DONE BY GLACIERS - glaciers spur - irregular shaped cliff
formed to move are embedded formed straightens smoothing retreating formed carved widens modify caused
by back-to-back erosion of cirques
forward
unique to glaciation 1
in the ice against the bedrock floor
by sideways
stream valleys
Flow of glaciers
by headwards erosion of several coalescing cirques
into a mountain wall at the head of a valley
the landscape
by removal of meanders 3