Geography: Unit 4 Glaciers

The big picture

During the ice age, water levels in the ocean were much lower than today. (up to 120m lower) That's because so much water was locked up in ice. The water drained away from shallow parts of the ocean floor. They became land.

But there were animals there 20000 years ago. There were woolly mammoths and bison and Artic foxes, which would survive the tundra winter. And in summer, when plants grew in the tundra, large herds of reindeer and antelope arrived from other parts of Europe, to feed.

What are glaciers?

Where are the glaciers?

Glaciers depend on snow. In those cold places, snow falls layer upon layer. Over time the layers below get compacted to ice, like when you squeeze a snowball very hard. It could take a layer of snow 10m thick to make a layer of ice 1m thick. As the ice gets heavier it starts to flow under the pressure of its own weight.

Where do they flow to?

Corrie
A corrie begins as a sheltered hollow, where snow buils up year after year.

Arête
when 2 corries form side by side, the glaciers erode the rock between them, leaving a sharp ridge of rock.

Pyramidal peak
when 3 or 4 corries forms around a mountain top. The glaciers erode their back walls, cutting into the mountain top.

U-shaped valley

Hanging valley

Moraines

Erratics

Drumlins

U-shaped valley on an OS map

Corrie on an OS map