3.1.4.3 Geomorphological Processes

Question 1

2 ways the rigid upper layer of ice travels

Answer 1

Uniformly

Quickest

Question 2

2 ways the plastic lower layer ice travels

Answer 2

None uniformly

Slowest at base

Question 3

Why are glaciers slower st valley walls and base

Answer 3

Friction

Question 4

What movement doesn’t exist in cold base glaciers

Answer 4

Basal slip

Question 5

What’s the main movement in cold based glaciers

Answer 5

Internal flow

Question 6

When does internal flow occur

Answer 6

Occurs when ice crystals orientate themselves in the direction of the glaciers movement and slide past each other

Question 7

3 stages to internal flow

Answer 7

Jumble of ice crystals

Ice crystals align under pressure

Ice crystals now slide over one another

Question 8

Why do ice crystals align in internal flow

Answer 8

Pressure

Question 9

7 movements in warm based glaciers

Answer 9

Basal flow/slippage
Regelation slip
Creep
extending flow
Compressing flow
Surges
Rotational flow

Question 10

When does basal sliding occur

Answer 10

When the overlying ice’s weight + friction. With bed and sides cause ice to melt
Encourages ice to move as it isn’t frozen to its base + meltwater acts as lubricant

Question 11

What causes the ice to melt at the bottom of the glacier for basal flow

Answer 11

Pressure and friction

Question 12

What 2 processes help basal flow

Answer 12

Regelation slip

Creep

Question 13

What happens in regelation slip

Answer 13

Obstacles to the ice flow (small<1m) create added pressure on the ice as it begins to move over them ;causing melting which aids the passage of ice over the obstacle

Question 14

What happens on the upside of the glacier in regelation slip

Answer 14

PMP decreases so it’s warmer and ice melts (higher pressure)

Question 15

What happens on the downside of the glacier in regelation slip

Answer 15

PMP increases
So it’s colder
Water refreezes (lower pressure)

Question 16

What are overcome by creep

Answer 16

Larger items

Question 17

What happens in creep

Answer 17

The ice acts like plastic and moulds itself around the obstacle as the ice crystals change shape/deform

Question 18

What’s creep all due to

Answer 18

Stress concentrations around larger obstacles on the bedrock floor

Question 19

When does compressing flow occur

Answer 19

Where there’s a reduction in gradient of valley floor

Question 20

What happens to the ice in compressing flow

Answer 20

Ice decelerates

Thickening of ice mass

Question 21

What’s at it’s maximum in compressing flow

Answer 21

Ice erosion

Question 22

When does extending flow occur

Answer 22

When the valley gradient become steeper

Question 23

2 things the ice does in extending flow

Answer 23

Accelerates

Becomes thinner

Question 24

What’s at it’s minimum in extending flow

Answer 24

Erosion

Question 25

When do surges occur

Answer 25

When an excessive build up of meltwater under the glacier leads to ice moving forward rapidly

Question 26

Who are surges a hazard to

Answer 26

People living in the glacial valley below the snout

Question 27

How much can surges move the glacier by in a day

Answer 27

250-300m

Question 28

Where does rotational flow occur

Answer 28

Within the Corrie, the birthplace of many glaciers

Question 29

What happens in rotational flow

Answer 29

Ice moving downhill can pivot about a point producing a rotational movement

Question 30

What combines with pivot water movement in rotational flow | What does this lead to

Answer 30

Pressure | Leads to greater erosion and an over deepening of the Corrie floor

Question 31

What can happen in extending flow due to higher velocity

Answer 31

The surface ice can break and crack

Question 32

Which flow has the most gravitational force

Answer 32

Extending flow

Question 33

Which temperature at he base causes faster ice movement | Why

Answer 33

Warm | More meltwater which lubricates base

Question 34

Why does ice move slower if the base is cold

Answer 34

Ice is frozen to bed rock and there's more friction

Question 35

What bedrock floor gradient causes ice to move faster | Why

Answer 35

Steeper | Greater pull of gravity

Question 36

What time of year do glaciers move fastest at | Why

Answer 36

Summer | More meltwater lubricates ice

Question 37

What thickness of ice causes ice to move faster | Why

Answer 37

Thicker | More potential energy but more force is needed to overcome friction

Question 38

What geology causes ice to move faster | Why

Answer 38

Impermeable rock | As more meltwater stays on rocks base and lubricates it

Question 39

Why do glaciers move slower with permeable rock

Answer 39

As meltwater goes into rocks and doesn't stay on surface so less lubrication

Question 40

How much friction causes ice to move faster

Answer 40

Less friction

Question 41

Why does ice move slower with more friction

Answer 41

As more ice is in contact with bed and valley sides

Question 42

What causes the ice in a glacier to move at different rates as it moves through a valley

Answer 42

The fractional drag between ice and rock

Question 43

What happens as the sides and base of a glacier move slower then the centre surface ice

Answer 43

The ice cracks producing crevasses on the surface

Question 44

2 other ways crevasses form

Answer 44

Where extending flow occurs (ice sped up) | Where the valley widens/ glacier spreads onto a plain

Question 45

Why do crevasses form when there extending flow or widening

Answer 45

As the surface ice is unable to adjust rapidly enough to extra stresses by basal slip/internal flow

Question 46

5 types of crevasses

Answer 46

``` Crevasses at margins (sides) Longitudinal crevasses Transverse crevasses Di radial splaying crevasses Bergschrund (large crevasses) ```

Question 47

Why do crevasses at margins form

Answer 47

As frictional drag between the ice and rock of the valley sides causes the margins to move slower then the centre

Question 48

What angle to crevasses open up at margins compared to old ones

Answer 48

New open up At an angle to the margin | Old ones may be bent/rotated round in direction of the glacial flow

Question 49

When do longitudinal crevasses occur

Answer 49

When the glacier spreads out laterally as the valley widens so there are stresses in the ice

Question 50

How do stresses in the ice act when forming longitudinal crevasses What position do crevasses open up in

Answer 50

At right angles to the margins so crevasses open up parallel to the glacier margins

Question 51

When do transverse crevasses occur

Answer 51

When a glaciers gradient steepens and extending flow occurs

Question 52

What shape are transverse crevasses upglacier | Why

Answer 52

Convex shaped | As the ice moves faster in the centre than the sides

Question 53

When do transverse crevasses close

Answer 53

When compressing flow occurs (gradient reduces)

Question 54

Where do di radial splaying crevasses splay out

Answer 54

In the glacier snout region from the spreading out of ice into a lobe

Question 55

What angles do di radial splaying crevasses also open up at to the direction of stresses

Answer 55

Right angles

Question 56

What's the bergschrund like | We're is it

Answer 56

A big semi circular crevasse | at the back of a glacier

Question 57

How is a bergschrund formed

Answer 57

By the tension caused by ice pulling away from the ice attached to the back wall