Cold 2- Glacial/Fluvioglacial landforms

Question 1

Weathering

Answer 1

The breakdown of rocks in situ

Finer particles are then moved away by the wind or running water

Question 2

Frost shattering

Answer 2

During the day water enters cracks and then freezes at nighttime, expanding by 9% and exerting pressure on the crack
This process repeats on bare rocky outcrops and the crack widens until pieces of rock break off (scree)

Question 3

Processes of glacial erosion

Answer 3

Abrasion- angular material wears away at the valley floor and sides
Plucking- the ice freezes onto rocky outcrops and as the glacier moves, pieces of rock stuck to the ice are pulled away

Question 4

Nivation

Answer 4

Snow collects in depressions and beneath it frost shattering occurs and also carbonation (carbonic acid corrodes rock like limestone)

Question 5

Corries

Answer 5

An enlarged armchair-shaped hollow with a steep back wall and an over-deepened basin

Question 6

Formation of corries

Answer 6

Hollow initially deepened by nivation
Accumulation of snow causes rotational flow, plucking occurs and then frost shattering provides debris for abrasion
Water trickles down Bergshcrund and more frost shattering occurs

Question 7

Arête

Answer 7

When two or more corries erode back to back towards each other from opposing sides, they produce a knife-edged ridge (e.g. Striding Edge)

Question 8

Pyramidal peak

Answer 8

When three or more corries erode back towards each other, a sharp point is formed (e.g. Matterhorn)

Question 9

Glacial troughs

Answer 9

Steep-sided, flat-floored (U-shaped) valleys

Question 10

Ribbon lakes

Answer 10

Compressing flow over-deep ends parts of the valley floor (less resistant rock) forming long, narrow lakes

Question 11

Truncated spurs

Answer 11

As glaciers move down a river valley, erosion along the valley sides may remove the tips of preglacial interlocking spurs

Question 12

Hanging valleys

Answer 12

When smaller tributaries join a main glacier, the smaller glaciers have less power to erode so the valleys are raised above the main valley (waterfalls form)

Question 13

Roches moutonnées

Answer 13

Small areas of more resistant rock on the valley floor which have a gentle upvalley side (stoss) polished by abrasion and a jagged downvalley side (lee) from plucking

Question 14

Craig and tail

Answer 14

Larger masses of more resistant rock (crag) and a gently sloping tail of less resistant rock and/or sediment on the downvalley side

Question 15

Types of debris

Answer 15

Supraglacial debris- on the surface of the glacier
Englacial debris- within the ice
Subglacial debris- beneath the ice

Question 16

Deposition

Answer 16

Till is all material deposited directly by the ice (unsorted)
Fluvioglacial material is sediments deposited by meltwater streams (sorted)

Question 17

Till

Answer 17

Individual stones remain angular
Lodgement till is from subglacial material (e.g. Drumlin)
Till produced at the snout is known as ablation till (end moraines)

Question 18

Erratics

Answer 18

Fragments of glacial debris

‘Rocks in the wrong place’

Question 19

Moraines

Answer 19

Lateral, medial, terminal and end moraine

Question 20

Drumlins

Answer 20

Rounded, oval-shaped hills formed from unsorted till deposits by the glacier
They have a steep upvalley stoss and a sloping downvalley lee eroded into a streamlined shape by the glacier

Question 21

Importance of meltwater

Answer 21

Enlarge nivation hollows, lubricate glaciers, frost shattering, transport fluvioglacial material

Question 22

Subglacial streams

Answer 22

Flow under considerable hydrostatic pressure from the glacier, so have high velocities and high capacity to carry material

Question 23

Outwash plains

Answer 23

An extensive, gently sloping area of sands and gravels that form in front of the glacier’s snout (stratified material)

Question 24

Eskers

Answer 24

Long, sinuous winding ridges of sediment deposited by subglacial streams

Question 25

Kames

Answer 25

Irregular, undulating mounds of sorted material, often steep sided and conical
Includes kame terraces, kame deltas and crevasse kames

Question 26

Kettles

Answer 26

A series of small depressions formed by deposition occurring around a block of ice, which subsequently melts to leave a hollow

Question 27

Varves

Answer 27

Layers of sediment deposited at the edge or in the bottom of meltwater lakes
Different bands from different seasons & years