Glaciation Flashcards
What is a glacier?
Large sheet of ice
What are ice sheets?
Masses of ice which covers large areas of a continent
What is accumulation?
More snow than melting
What is ablation?
More melting than snow
What is frost shattering? (freeze-thaw weathering)
-Water that enters cracks in rocks freezes, and when it does it expands.
-Repeated freeze and thaw means cracks in the rocks expand until rock is fractured.
-This leads to material falling off the side of the mountain slopes onto glaciers.
What is abrasion?
-the wearing away of the rock at the base and sides of the glacier by the scouring action of ice containing rocks plucked from the Earth’s surface, the ice acts as an enormous sheet of sand paper.
-the grinding leaves long grooves in the bedrock called Striations or a smooth Polish finish (rock which is smooth and shiny)
-Striations are important as they show direction the ice moved!
What is plucking?
-the tearing away of blocks of rock which have became frozen onto the rock base and sides of a glacier.
-plucking occurs when rocks and stones become frozen to the base of a glacier and are plucked’ from the ground as the glacier moves.
How are corries are formed?
When snow collects in a natural hollow on the side of a mountain. Over time more snow collects, this extra weight compresses the snow underneath, turning it to ice.
What is an atête?
A steep rocky ridge between two corries
How is an arête formed?
When two corries run back to back
Name for the lake that forms in a corrie?
A Tarn
What is a Tarn?
A lake that forms in a corrie
How are pyramidal peaks formed?
When 3 or more corries cut backward into the same mountain
How is a U-shaped Valley formed?
-as the glacier flows down an old V-shaped valley
-as the glacier flows it erodes the sides and bottom of the valley by abrasion and plucking.
-the valley becomes U-shaped with very steep sides and a flat bottom.
How are Drumlins formed?
They are formed from boulder clay (sometimes called Till). They are elongated (stretched out) features.
