glaciers geography

abrasion

rocks eroding by scraping the deposit like sandpaper.

plucking

when the ice moves, it scrapes away some rocks around the surface.

What is freeze-thaw weathering?

A process where water enters a crack in a rock, freezes, and expands the crack.

What happens when water freezes in a crack in a rock?

The water expands the crack.

What is the result of repeated freeze-thaw cycles on rocks?

The pressure releases and the rock cracks.

basal sliding

the sliding of a glacier over bedrocks.

glacial till

sediment deposited by ice. The rocks are angular and not sorted.

glacial outwash

sediment rounded by attrition and carried by meltwater. Larger pieces require more energy.

bulldozing

as the glacier moves forward, it pushes loose debris in front of it.

pyramidal peak

Where three or more corries and arêtes meet.

What is a corrie?

A deep rock basin with a steep back wall.

What can sometimes be found in a corrie?

A tarn.

What is a truncated spur?

Rounded areas of land which have been cut off.

How is a truncated spur formed?

When a valley glacier cuts through any previously interlocking spurs.

hanging valley

a valley that is cut across by a deeper valley or a cliff.

glacial trough

a mountain valley that has been widened, deepened, and straightened by a glacier

ribbon lake

a long, narrow lake in the bottom of a glacial trough.

arete

a sharp, narrow ridge of rock found at the back of a corrie.

maximum ice cover extent

all of Scotland and Ireland, most of Wales and the North of England.

erratics

isolated boulders left behind by a glacier:

-very out of place

-can also be found in the Atlantic Ocean on the seafloor

drumlins

smooth egg-shaped hills which are 10m high and hundreds of meters long. They are made of moraine and indicate the direction of movement of a glacier.

Moraine

different types of glacial deposit.

ground moraine

material which is dragged underneath the glacier and is left behind when the ice melts.

lateral moraine

moraine which forms at the edge of a glacier. Mainly scree material which has fallen off the sides of the glacier due to freeze thaw weathering.

terminal moraine

large amounts of material that pile up at the snout of the glacier to form a high ridge.