2. Depositional landforms

Question 1

What are the depositional landforms?

Answer 1

Moraines
Erratics
Drumlins
Till sheets

Question 2

What are the three types of moraine?

Answer 2

TERMINAL MORAINE:
A ridge of till extending across the end of a glacial trough, it marks the position of maximum advance of the glacier. Often crescent shaped with centre being further forward due to less friction in middle from valley sides.
Eg. Franz Josef Glacier has clear terminal moraine 430m high

LATERAL MORAINE: A ridge of till running along the edge of a glacial trough. Material accumulate at the side due to it being weathered on the rock above.
Eg. Athabasca Glacier has lateral moraine 1.5km long

RECESSIONAL MORAINE: A series of ridges of till that are parallel to each other, formed when the glacier has a temporary stand-still in its retreat.

Question 3

What is an erratic?

Answer 3

An individual rock that has a different geology to that of the surround area. Either plucked or weathered in one area then transported and deposited to another area.
Eg. Erratics of silurian shale deposited on limestone at Norber in Yorkshire Dales

Question 4

What are drumlins?

Answer 4

A mound of glacial debris that has been elongated into a streamline hill. Often forms a ‘basket of eggs’ and can be more than a km long and over 100m high. Stoss end is higher and wider whereas as lee side is more gently tapered.
Eg. Hills of Elslack, North Yorkshire

Question 5

What are the two theories of drumlin formation?

Answer 5

1. Subglacial bed deformation (Menzies in 1979) - successive build up of sediment underneath the ice with the more easily deformed till becoming the elongated lee side
2. Cavity-fill meltwater model (Shaw in 1989) - as a result of meltwater erosion, large floods beneath the ice eroded hollows and were filled with sediment.

Question 6

What is a till sheet?

Answer 6

An unsorted mix of rock, sand and clay that is left when an ice sheet retreats and can extend for many miles.

Question 7

Describe the rocks in a till sheet:

Answer 7

The rocks are sub-angular meaning they aren’t extremely sharp but not rounded either - the till sheets represent the geology the ice has passed over.
Eg. Chalky deposits in East Anglia