Depositional Landforms

Question 1

whats a moraine

Answer 1

• Moraines are distinct ridges or mounds of debris that are laid down directly by a glacier or pushed up by it.
• The term moraine is used to describe a wide variety of landforms created by the dumping, pushing, and squeezing of loose rock material, as well as the melting of glacial ice.

Question 2

whats a terminal moraine

Answer 2

• is a moraine ridge that marks the maximum limit of a glacier advance.
• They form at the glacier terminus and mirror the shape of the ice margin at the time of deposition.
• The largest terminal moraines are formed by major continental ice sheets and can be over 100 m in height and 10s of kilometres long

Question 3

whats a lateral moraine

Answer 3

• Form along the glacier side and consist of debris that falls or slumps from the valley wall or flows directly from the glacier surface.
• Where the rate of debris supply is high, lateral moraines can reach heights of more than 100 metres

Question 4

whats recessional moraine

Answer 4

• are found behind a terminal moraine limit and form during short-lived phases of glacier advance or still stand that interrupt a general pattern of glacier retreat.
• In some cases, recessional moraines form on a yearly basis (normally as a result of winter glacier advances) and are known as annual moraines

Question 5

what are erratics

Answer 5

• rocks that have been transported by ice and deposited elsewhere. The type of rock (lithology) that the glacial erratic is made from is different to the lithology of the bedrock where the erratic is deposited.

Question 6

what are drumlins

Answer 6

oval or elongated hill believed to have been formed by the streamlined movement of glacial ice sheets across rock debris, or till.

Question 7

drumlin formation

Answer 7

there formation aren’t funny understood but they are guessed:

• lodgement of subglacial debris as it melts out of the basal ice layers
• reshaping of previously deposited material during a subsequence of re-advance
• accumulation of material around a bedrock obstruction these are known as rock cored drumlins
• thinning of ice as it spread out over a lowland area reducing its ability yo carry debris

Question 8

whats a till sheet

Answer 8

a uniform blanket of glacial deposits in a lowland

Question 9

how’s a till sheet formed

Answer 9

when a large mass off unstratified drift is deposited at the end off a period of ice sheet advance which smoothes the underlying surface