physical Envi - Glaciation

Question 1

The three processes of abrasion

Answer 1

freeze thaw weathering, plucking and abrasion

Question 2

Abrasion for glacial errosion (corrie) -

Answer 2

Abrasion: when angular rocks embedded in the ice grinds the hollow

Question 3

freeze thaw weathering

Answer 3

when water in cracks freezes, expands and contracts weakening the rock until fragments break off

Question 4

Plucking

Answer 4

when ice freezes onto bedrock, pulling loose rocks away from the back wall

Question 5

example of a corrie

Answer 5

cwm idwal in wales

Question 6

how is a corrie formed? - might appear

Answer 6

Snow gathers in north facing mountain hollows, where there is more shade. snow builds up and compacts to neve. The action of gravity means the ice slowly moves downhill. As it goes, it sticks to back walls and plucks rock from the surface, this is the process plucking. Rocks on the backwalls are loosened by tweeze thaw. Ice from plucking act like sandpaper and deepens the hollow by abrasion, Stones frozen in the base of the ice grind or abrade the corrie base, deepening it. Ice in a corrie has a rotational movement which means that the front of the corrie is less eroded, and a lip forms. The glacier retreats and melts, often leaving a tarn in the base of the corrie.

Question 7

example of a U shaped valley

Answer 7

The Nant Francon Valley, Snowdonia

Question 8

what features does a U shape valley have?

Answer 8

truncated spurs, a ribbon lake and hanging valleys

Question 9

how does a ribbon lake form? - not likely

Answer 9

When there is a section of less resistant rock beneath the glacier, it can be eroded away more than rock around it, this leaves a hollow or depression that then fills with water. like a ribbon lake

Question 10

Erratic’s and things like the kettle holes are all what features?

Answer 10

glaciation deposition features

Question 11

what is a large rock that is deposited by the movement of a glacier. The rock type is usually different from others as its been moved from a different valley. Its left exposed when the glacier retreats

Answer 11

Erratic - likely to be asked

Question 12

what is a moraine?
(rock left behind moving glacier)

Answer 12

terminal moraine’s are at the end of the glacier. Made from unsorted material and can create a lip behind which a lake can then form in

Question 13

Kettle hole - likely to appear

Answer 13

Its a hollow filled by a lake. Large blocks of ice leave behind a depression on the out-wash plane when the glacier retreats leaving behind a deeper hollow. The hole fills with water due to rain collection

Question 14

Drumlins

Answer 14

Are smooth, oval mounds created in groups. Deposited material gets dragged along by a glacier with the lower section being smooth and the steep side facing the glacier. Unsorted material is due to the lack of fluvial movements

Question 15

Explain an esker

Answer 15

Its a long narrow ridge or mound of sand, gravel and boulders that are deposited by melt-water from tunnels within and below the glacier. Eskers are located on the sides of glaciers after it retreats and are made from sorted material. Braided eskers and single ridge eskers are a thing

Question 16

What do you do for the command word “Explain”

Answer 16

explain what it is and the processes

Question 17

how do you answer a question using the command word “describe”

Answer 17

describe the features/what you would see and find