Glacial Landforms

Question 1

Outwash plain formation

Answer 1

As the glacier melts at the snout, it deposits moraine as it has less energy and this is deposited according to size
Smaller material is deposited further from the glacier

Question 2

Terminal moraine

Answer 2

Marks maximum advance of the glacier - forms in a arc

Question 3

Recessional moraine

Answer 3

Mark periods where the glacier remained still for deposition to occur

Question 4

Push moraine

Answer 4

Formed when glacier re-advances after retreat (previous recessional moraine pushed into a mound)
Contains more fluvioglacial deposits

Question 5

Lateral moraine

Answer 5

Runs parallel to the direction of ice flow

Caused by friction with the valley sides and contributed to by freeze-thaw above

Question 6

Medial moraine

Answer 6

Formed when two valley glaciers meet as the two lateral moraines converge
Insulate ice below, reducing abrasion and raising them above the main glacier

Question 7

Subglacial moraine

Answer 7

Deposited as a blanket of till when the glacier loses energy

Question 8

Varves

Answer 8

Coarse, light sand deposited in Spring when meltwater streams have peak discharge and have the maximum load
Finer, darker silt deposited in Autumn when meltwater discharge decreases
Hotter years lead to more melting, more deposition and thicker varves

Question 9

Kettle

Answer 9

Blocks of dead ice left behind by retreating glaciers and subsequently surrounded by sediment
When the ice melts, a depression is left (kettle hole)
Lakes often fill these depressions

Question 10

Delta Kames

Answer 10

Meltwater streams flow into a proglacial lake, depositing any sediment they are carrying, forming a fan-shaped delta

Question 11

Crevasse Kames

Answer 11

Meltwater streams enter crevasses
As water percolates friction increases, depositing sediment
As the ice melts, the material slumps to the ground forming a crevasse kame

Question 12

Kame Terraces

Answer 12

Friction on valley sides causes ice melt, creating meltwater streams at the side of valleys
Material is deposited in these channels, slumping when the glacier melts to form terraces at the side of a valley

Question 13

Eskers

Answer 13

Subglacial meltwater rivers form a network of interlinked tunnels
High water pressure in these channels = ^ load carrying capacity
In winter, discharge decreases, leading to high deposition
When the glacier melts, this material forms eskers

Question 14

Drumlins

Answer 14

A glacier deposits material subglacially

This material is then moulded by the glacier as it passes over it, to form a drumlin shape

Question 15

Braided streams

Answer 15

Intermittent flow of meltwater streams and the various discharge
High levels of sediment deposited leads to eyots or bars
Meltwater then weaves between these bars
The formation can change do the ease of erosion of the bars/eyots

Question 16

Aretes

Answer 16

Two U-shaped valleys run parallel or when two corries erode headward
Aretes are sharpened by freeze-thaw

Question 17

Corries

Answer 17

Form on North of mountain
Nivation (freeze-thaw) creates a hollow
Accumulation leads to diagenesis, leading to its enlargement
Plucking occurs on the backwall, weakened by freeze-thaw and dilation
Rotational flow occurs due to a steep back and shallow front - this forms a Bergschrund crevasse, in which scree falls
Thinner ice at the front (rotational flow) allows for a rock-lip to form in the low energy zone

Question 18

Ribbon lakes

Answer 18

Differential erosion caused by softer rock allows deepening of certain areas of the valley
Pressure release occurs as the glacier retreats, weakening the rock
Moraine can act as a dam

Question 19

Pyramidal peaks

Answer 19

3 or more corries erode headward

Requires cold conditions on all sides and long periods of glaciation

Question 20

U-shaped valley

Answer 20

Greater erosional power leads to carving of valley walls

Question 21

Truncated spurs

Answer 21

Interlocking spurs are eroded, blunting them

Question 22

Hanging valleys

Answer 22

Small tributary glaciers have less erosive power so carve a small valley above the main trough
Waterfalls may develop post-glaciation

Question 23

Alp Benches

Answer 23

Elements of the original v-shaped valley remain at the margins of a deeper glacial trough, where the ice didn’t reach

Question 24

Roche Mountonnee

Answer 24

Pressure melt on the upside of an obstacle aid abrasion and creates a smooth profile
Pressure release on the downside of an obstacle, meaning plucking occurs due to refreezing

Question 25

Striations

Answer 25

Large rocks cut grooves due to high pressure, in the direction of glacier movement
Finer sediment acts as sandpaper, smoothing the rock

Question 26

Crags and tails

Answer 26

Crag: Form when a glacier cannot erode a piece of resistant rock, but erodes the material around it instead
Tail: The crag shelters softer material in its lee, protecting it from further erosion and forming a gradual ridge