Glaciated Landscapes EQ 2

Question 1

Components of a glacier system

Answer 1

Inputs
Dynamic equilibrium 
Energy 
Outputs 
Stores and components 
Flows and transfers 
Feedback loops

Question 2

What are inputs in glaciers

Answer 2

• Precipitation in the form of snowfall, which is compacted over many years to form high density ice.
• Avalanches
• Wind deposition, where strong winds at high altitudes deposit snow

Question 3

Dynamic equilibrium

Answer 3

• Is the boundary between accumulation zone and ablation zone
• As balance shifts the equilibrium will move up or down

Question 4

Energy

Answer 4

Glacier mass combined with gravity generate potential energy. As glaciers move down potential energy is converted into kinetic energy. This enables transportation, erosion and deposition

Question 5

Outputs

Answer 5

Melt water
Ice calving where ice may break off to form icebergs
Evaporation or sublimation

Sublimation is where a solid changes to a gas with no liquid stage

Question 6

Stores and components

Answer 6

Main stores are snow and ice which change seasonally

Over the last 40 years stores have been decreasing

Question 7

Flow and transfers

Answer 7

Processes such as meltwater flow and processes of glacial movement such as internal deformation and basal sliding.

Flows and transfers are more active in warmer environments than colder ones

Question 8

Feed back loops - negative

Answer 8

Wants to maintain dynamic equilibrium to minimise effect of outputs:
- Increased snowfall will increase volume of accumulation, with increased volume of accumulation there will be increases ablation. Glacier will maintain dynamic equilibrium.

Question 9

Feed back loops - positive

Answer 9

AMPLIFY initial change and may cause a shift in the system to an new state of equilibrium:
- If a glacier has a positive ice mass balance, this increases the albedo effect due to high surface energy. This reduces air temperature causing the glacier to advance.

Question 10

Factors that cause variation in rate of ablation

Answer 10

Solar radiation
Feedback loops
Warm base or cold base
Type of environment

Question 11

Factors that effect the accumulation zone

Answer 11

Level of precipitation
Average temperatures
Insulation levels
Wind speeds - strong winds at high altitude deposit more snow.
Poleward aspect - south facing or north facing

Question 12

Internal deformation

Answer 12

Happens in both warm and cold environments.

2 types of internal deformation:

• Intergranular flow, where ice crystals slip and slide over each other to flow downhill
• Laminal flow, where there is movement of individual layers within the ice

Question 13

Extensional flow

Answer 13

An increasing gradient causes ice to flow faster and due to internal deformation the ice becomes stretched and crevasses are created.

Question 14

Compressional flow

Answer 14

Reduction in gradient means ice flows slower. This cause the ice to pile up and thicken. Some crevasses close while some open up.

Between extensional and compressional flow, ice moves in a rotational manner

Question 15

Transverse crevasses

Answer 15

Cuts across glaciers at right angles

Question 16

Radial crevasses

Answer 16

Form in a splayed pattern at the snout of the glacier, where ice spreads out in a broad lobe.

Question 17

Marginal crevasses

Answer 17

Forms near the side where there are different rates of movement due to friction at the sides.

Question 18

Surge

Answer 18

A great amount of ice movement 100 times faster due to tectonic activity such as volcanic eruptions. This releases a great amount of meltwater which also acts as a lubricant.

Question 19

Subglacial bed deformation

Answer 19

Sediment can dorm under the weight of the glacier, moving ice on top along with it.

Question 20

Basal sliding

Answer 20

Happens in only warm base environments.

Involves the movement of large blocks of ice in short jerks. It occurs where meltwater is present to lubricate the base of the glacier.
2 types: enhanced basal creep, and regulation creep.

Question 21

Regulation creep

Answer 21

Where basal ice melts under localised pressure when it encounters and obstacle. This allows the glacier to flow over it and when pressure is lowered the meltwater refreezes.

Question 22

Enhanced creep

Answer 22

Where basal ice deforms around irregularities on the bedrock surface.

Question 23

Feed back cycles of ice movement - negative

Answer 23

A negative feedback - at increasing ice depth the melting point of ice is lowered by pressure. As thickness increases, there is increased pressure and basal slip so ice move faster. In return this reduces ice thickness and reduces pressure melting point and basal slip.

Question 24

Feed back cycle of ice movement - positive

Answer 24

An increase in basal melt water will increase basal slip, which generates frictional heat and increases basal slip.

Question 25

Factors that control the rate of ice movement

Answer 25

Gradient- increasing gradient increases flow ice
Meltwater- lubricates base enabling it to slip down hill
Ice temperatures- cold base or warm base
Altitude- affect precipitation and temperature
Permeable or impermeable surfaces- meltwater is retained or not
Friction- ice has to overcome it to move.
Size- an increase in size mean low pressure melting points

Question 26

Glacial erosion

Answer 26

Abrasion
Plucking
Fracture and traction
Meltwater erosion

Question 27

Entrainment

Answer 27

The process by which surface sediment is incorporated into a fluid flow as part of the process of erosion

Question 28

Abrasion

Answer 28

Occurs because of entrainment- large rocks carried below the ice scratch the surface to form striations or scratches

Question 29

Plucking

Answer 29

When meltwater freezes to a part of the bedrock. Any loose rock fragments are pulled away as glacier the slips forwards.

Question 30

Fracture and traction

Answer 30

Variation in pressure leads to freezing and thawing of meltwater. This aids plucking.

Question 31

Meltwater erosion

Answer 31

Glacial meltwater dissolved minerals and carry away salutes

Question 32

Glacial transportation

Answer 32

Supraglacial- debris transported on the surface of the glacier.
Subglacial - debris transported beneath the glacier
Englacial- debris transported inside the glacier

Question 33

Glacial deposition

Answer 33

When material is released form the ice at the margin or the base o f the glacier. Deposition may occur on the ground or released in meltwater.
Deposition mechanisms: release of debris by melting, sublimation, release from meltwater and remodelling of deposition.

Question 34

Glacial landforms occur in different environment

Answer 34

Subglacial - below a glacier
Marginal - at the side of the glacier
Proglacial - in front of the glacier or ice sheet

Question 35

Different scales for landforms from largest to smallest

Answer 35

Macro scale

Meso scale

Micro scale

Question 36

Macro scale landforms

Answer 36

Moraines, block fields, ice wedges, pingos, cirques, glacial troughs, till plains, terminal moraines, Sandurs

Question 37

Meso scale

Answer 37

Kettle holes, ribbon lake, eskers, Roche moutonée, crag and tail, Kame terraces, drumlins

Question 38

Micro scale

Answer 38

Chatter marks, striations, glacial grooves, erratics

Question 39

Landform evidence

Answer 39

Upland areas are characterised by erosion although landforms such as carries, glacial troughs and hanging valleys.

Lowland areas tend to have more deposition landforms such as outwash plains and glacial till deposits. Boulder clay tells us that these are areas of glacial deposition that represent former outwash plains. Found in holderness and east anglia. Carries, tarns and glacial troughs in the Lake District provide evidence that glaciers were active in that area.

Question 40

Variations in glacier mass balance at annual and longer term scales

Answer 40

Levels of precipitations, increased precipitation means accumulation is greater than ablation. This will change the glaciers equilibrium. Precipitation vary annually depending on temperature.

Albedo effect, when there is higher albedo affect temperatures will be lower as radiation is reflected away. This results in more precipitation due to lower temperatures. This is a positive feedback cycle.

Different seasons. In summer ablation is greater than accumulation and glacier shrinks. This is a negative regime. In winter accumulation is greater than ablation and this is a positive regime.