Glaciers Flashcards
Conditions needed for glaciers to form
An average annual temperature of around 0C
Lots of snow in the winters
At no point in the year are temperatures high enough to melt all the snow that fell in the last winter
What are arêtes?
Narrow, steep ridges that form when two glaciers flowing in parallel valleys erode the sides of their valley.
What are pyramidal peaks?
Peaks are pointed with 3+ sides. These are formed when 3+ glaciers erode different sides of a mountain.
What are hanging valleys?
Created by smaller glaciers that join up with the main glacier. Because the smaller glacier erodes less powerfully, its valley is much shallower.
What are ribbon lakes?
Very thin and long lakes that are formed in the hollows in glacial troughs when glaciers retreat.
What are corries?
Steep hollows with a lip at the bottom. Corries are shaped like armchairs. These are formed by a rotational slip of small glaciers.
What are tarns?
Circular lakes left behind in corries when glaciers melt.
What are glacial troughs?
Valleys with steep sides, but a flat floor. As erosion takes place, the glacial trough becomes wider and deeper.
What are truncated spurs?
Sheer faces on the side of glacial troughs. These are formed when spurs are cut off as the glacier moves.
What is a cirque?
As the ice melts and thaws and progressively moves downhill more rock material is scoured out from the cirque creating the characteristic bowl shape.
What is freeze-thaw weathering?
Water entering rocks cracks then freezing and expanding adding pressure then when the water melts it causes rocks to fall off.
What is plucking?
When rocks and stones become frozen to sides of the glacier and as the glacier moves they are plucked from the rock face. This leaves behind a jagged landscape.
What is abrasion?
When rocks and stones become embedded in the base sides of glaciers. These are then rubbed against the bottom of the glacier and sides of the glacier as it moves causing abrasion.
What is a rotational slip?
Where a glacier gets heavier and moves downhill. It moves out a circular motion by rotational slip.
