Glaciation

Question 1

What is a Corrie?

Answer 1

A Corrie is an “armchair-shaped” hollow which forms in the side of a mountain.

Question 2

What are the features of a Corrie?

Answer 2

Features of a Corrie include steep backwalls, scree, a corrie loch, and a deep hollowed base.

Question 3

How is a Corrie formed?

Answer 3

Friction causes the ice to slow down at the front edge of the corrie, allowing a rock lip to form which traps rainwater.

Question 4

What is plucking in the context of a Corrie?

Answer 4

Plucking is when ice freezes onto bedrock, pulling loose rocks away from the sides.

Question 5

Why do glaciers form on the north/north east slopes of mountains?

Answer 5

North/north east slopes are shaded from the sun so snow lies longer, leading to accumulation and compression into ice.

Question 6

What causes glaciers to move downhill?

Answer 6

Glaciers move downhill due to gravity.

Question 7

What is abrasion in glacial processes?

Answer 7

Abrasion is when angular rock embedded in the ice scrapes away at the valley floor.

Question 8

What is a bergschrund crevasse?

Answer 8

A bergschrund crevasse may open up at the back of the hollow allowing meltwater and rocks to get to the base of the glacier, increasing its erosive power.

Question 9

What is freeze-thaw weathering?

Answer 9

Freeze-thaw weathering is when water in the cracks in the rocks freezes, expanding and contracting, weakening the rock until fragments break off.

Question 10

Can you give an example of a Corrie?

Answer 10

An example of a corrie is Lochnagar.

Question 11

What is an Arete?

Answer 11

An Arete is a knife-edged ridge which forms when two Corries erode back to back toward each other.

Question 12

What is a U-shaped valley?

Answer 12

A U-shaped valley has steep sides and a wide, flat valley floor.

Question 13

How does a glacier form in a valley?

Answer 13

A glacier forms in a north/north east facing valley which is shaded from the sun.

Question 14

What happens to snow in a glacier?

Answer 14

As snow compresses, it forms glacial ice. The ice then moves downhill due to gravity.

Question 15

What is plucking in glacial processes?

Answer 15

Plucking is when ice freezes on to the sides of the valleys and pulls loose rocks out as it moves.

Question 16

What is freeze-thaw weathering?

Answer 16

Freeze-thaw weathering is when water enters cracks in the rock and freezes, expanding and contracting again and again until pieces of rock are broken off.

Question 17

What is abrasion in glacial processes?

Answer 17

Abrasion is when angular rocks embedded in the ice scrape away at the valley floor.

Question 18

What are interlocking spurs?

Answer 18

Interlocking spurs are cut off by the glacier to form truncated spurs.

Question 19

Can you provide an example of a U-shaped valley?

Answer 19

An example of a U-shaped valley is in Glencoe.

Question 20

What is a misfit stream?

Answer 20

When the river returns to the valley, it does not fit the width of the valley floor so is known as a misfit stream.

Question 21

What is a ribbon lake?

Answer 21

A long, narrow lake formed by glacial erosion.

Question 22

What type of rock does a glacier find difficult to erode?

Answer 22

Hard rock.

Question 23

What type of rock does a glacier easily erode, forming a rock basin?

Answer 23

Soft rock.

Question 24

What geological feature may be deposited by a glacier that can also dam a lake?

Answer 24

Moraine.

Question 25

Fill in the blank: A glacier finds it difficult to erode _____ rock.

Answer 25

[hard rock]

Question 26

Fill in the blank: A glacier easily erodes _____ rock forming a rock basin.

Answer 26

[soft rock]

Question 27

True or False: A glacier can easily erode both hard and soft rock.

Answer 27

False.

Question 28

What does moraine do in relation to a ribbon lake?

Answer 28

It can dam the lake.

Question 29

How does a glacier affect soft rock compared to hard rock?

Answer 29

It easily erodes soft rock but finds it difficult to erode hard rock.

Question 30

Named example of ribbon lake

Answer 30

Loch muick

Question 31

What are hanging valleys?

Answer 31

Hanging valleys are formed from tributary valleys that flow into the main river below.

Question 32

How do hanging valleys form during glaciation?

Answer 32

During glaciation, tributary valleys fill with smaller glaciers that have less erosion power than the main glacier.

Question 33

What happens to tributary valleys after glaciation?

Answer 33

After glaciation, tributary valleys are cut off by the main valley glacier, leaving them ‘hanging’ above the main valley.

Question 34

What is usually found in a hanging valley when rivers return?

Answer 34

A hanging valley is usually marked with a waterfall when the rivers return.

Question 35

How do interlocking spurs become truncated?

Answer 35

This question requires further exploration.

Question 36

What is a misfit stream?

Answer 36

A misfit stream is a stream that is too small for the valley it occupies.

It gets its name from its size relative to the valley.

Question 37

What causes a ribbon lake to form on the floor of a u-shaped valley?

Answer 37

This question requires further exploration.

Question 38

What causes a hanging valley?

Answer 38

Hanging valleys are caused by the differential erosion of tributary valleys during glaciation.

Question 39

What can we explain regarding glacial deposition?

Answer 39

We can explain the formation of depositional features in glaciated landscapes.

Question 40

What are the erosional features in glaciated uplands?

Answer 40

The erosional features include: Corrie, Arete, Pyramidal Peak, U-shaped Valley, Truncated Spur, Hanging Valley, and Ribbon lake.

Question 41

What are the depositional features in glaciated uplands?

Answer 41

The depositional features include: Terminal Moraine, Drumlins, and Eskers.

Question 42

What is drift in glacial deposition?

Answer 42

Drift is all glacial deposition material.

Question 43

What is till?

Answer 43

Till is unsorted, angular material dragged under the glacier.

Question 44

What is fluvioglacial material?

Answer 44

Fluvioglacial material is sorted, rounded material sorted by glacial meltwater.

Question 45

What is a moraine?

Answer 45

Moraine is all material accumulated during glaciation, including silt, clay, sand, gravel, stones, and rocks, which have been picked up, moved, and deposited by the glacier.

Question 46

What is a terminal moraine?

Answer 46

Terminal moraine is a ridge across the valley made up of till of different sizes, marking the furthest extent of the glacier.

Question 47

How does a terminal moraine form?

Answer 47

As the glacier moves downhill, it acts like a bulldozer, pushing sediment in front of its snout. When it reaches an area of higher temperature, the ice at the snout melts, leading to deposition of till.

Question 48

What happens to the terminal moraine as the glacier stays in one place?

Answer 48

The longer the glacier stays, the more deposition occurs, making a larger terminal moraine.

Question 49

What is lateral moraine?

Answer 49

Lateral moraine forms along the sides of the glacier from material that falls onto the glacier due to freeze-thaw weathering.

Question 50

What is medial moraine?

Answer 50

Medial moraine forms when the lateral moraine of two glaciers join.

Question 51

What are drumlins?

Answer 51

Drumlins are long oval ridges sculpted from unsorted glacial till.

Question 52

How do drumlins form?

Answer 52

Drumlins form when the glacier becomes overloaded with sediment, depositing it and streamlining the sediment as it flows over it.

Question 53

What is the shape of drumlins?

Answer 53

Drumlins have a steep ‘stoss’ slope facing up-valley and a gentle ‘lee’ side facing down-valley.

Question 54

What are eskers?

Answer 54

Eskers are meandering ridges formed by meltwater streams in or under a glacier.

Question 55

How do eskers form?

Answer 55

Eskers form as meltwater streams deposit sorted material on the channel bed as the glacier melts.