Formation of Landscape Features by Glaciers Flashcards
What is a cirque?
An amphitheatre-like valley formed by glacial erosion
Alternative names include corrie and cwm. The concave shape is open on the downhill side.
Define a tor.
A large, free-standing rock outcrop that rises abruptly from surrounding slopes
Tors are usually no more than 15 meters high and are formed by freeze-thaw weathering or groundwater weathering.
What are U-shaped valleys also known as?
Trough valleys or glacial troughs
Characterized by steep, straight sides and a flat or rounded bottom.
What are hanging valleys?
Valleys found high on the sides of larger U-shaped valleys
They begin as corries and evolve into elongated corries or small U-shaped valleys due to erosion.
What is an arête?
A narrow ridge of rock that separates two valleys
Formed when two glaciers erode parallel U-shaped valleys.
What defines a horn or pyramidal peak?
A high triangular peak formed by three or more glaciers eroding toward each other
What are glacial striations?
Scratches or gouges cut into bedrock by glacial abrasion
What is a Roche moutonnée?
A rock formation created by the passage of a glacier
Features asymmetric erosional forms due to abrasion and plucking.
Define moraines.
Accumulations of unconsolidated debris carried along by a glacier or ice sheet
Sometimes referred to as glacial till.
What is an end/terminal moraine?
A moraine that forms at the terminal edge of a glacier, marking its maximum advance
What is a recessional moraine?
A moraine left by a glacier during a temporary halt in its retreat
What are lateral moraines?
Sharp-crested piles of debris dropped by melting ice, forming only in the ablation zone of a glacier
What are medial moraines?
Moraines formed where two tributary glaciers converge
What are ground moraines?
Sediments built up directly underneath a glacier, exposed when the glacier melts
What is a kame?
An irregularly shaped hill or mound composed of sand, gravel, and till deposited by a retreating glacier
Define drumlins.
Oval-shaped hills formed beneath a glacier, aligned in the direction of ice flow
What are eskers?
Ridges made of sands and gravels deposited by glacial meltwater flowing through tunnels or channels
What is an erratic?
A glacially deposited rock differing from native rock types in the area
Erratics can be carried over distances of hundreds of kilometers.
What is a tarn?
A mountain lake formed in a cirque excavated by a glacier
A moraine may form a natural dam below a tarn.
What are the Great Lakes?
A series of large interconnected freshwater lakes spanning the Canada–United States border
The five lakes are Superior, Michigan, Huron, Erie, and Ontario.
Define the Finger Lakes.
A group of eleven long, narrow lakes located south of Lake Ontario
What are kettles?
Depressions formed by retreating glaciers or draining floodwaters
Created by blocks of dead ice surrounded by sediment from meltwater streams.
What are moraine-dammed lakes?
Lakes formed when terminal moraines prevent meltwater from leaving the valley
What is a proglacial lake?
A lake formed by the damming action of a moraine during glacier retreat
Can also form from glacial ice dams or trapped meltwater.
