EQ 2

Question 1

What is dynamic equilibrium

Answer 1

Equilibrium is the boundry between the accumulation and ablation zone, this line will move depending on the differences in transfers. Move = dynamic

Question 2

What is the accumulation zone of the glacier

Answer 2

Are of the glacier where inputs are greater than outputs

Question 3

what are the main stoes in a glacial system

Answer 3

snow + ice - vary due to seasonality and common trend now is that stores are decreasing which has been attributed to global warming

Question 4

which energies operates the glacial system

Answer 4

GPE KE and SOLAR

Question 5

what processes are dominant in the accumulation zone

Answer 5

Inputs: avalanches, snowfall, wind delivering matter (mostly snow),
freeze thaw weathering giving scree fall to glacial system

Question 6

what processes are dominant in the ablation zone

Answer 6

Suora/sub - glacial steamswash out meltwater carrying sediment
Ice calving
sublimation due to solar radiation
evaporation

Question 7

what feeback loops occur in glacial systems

Answer 7

positive: Ice moves, creating meltwater and less friction
negative: more melt. less mass, less gpe energy so less KE, less melting and ablation

Question 8

How does mass balance contribute to understanding of global systems

Answer 8

• Growth or decrease in glacial size depends on mass balance
• budget is calculated by dividing the glacier into two zones
• accumulation is net gain and ablation is net loss
• mass balance varies over the course of a year, ablation is at its highest during the summer and accumulation the lowest and vice verse during the winter
• Glacier advance and retreat due to long term patterns in the mass balance, more mass + advance, less mass + retreat

Question 9

What factors cause variation in the rate of ablation

Answer 9

Rates of ablation and accumulation vary with climate

• Solar radiation
• Average temperatures
• Proximity to sea (ice calving)
• Altitude (higher you go the lower the temperatures)
• Slope orientation (facing towards sun)
• Feedback loops, increase in meltwater feedback loop and decrease in mass loop

Question 10

How does Lithology impact glacier movement

Answer 10

In temperate zones:
Permeable: water percolates away and does not reduce friction
Immpermeable rocks: meltwater does not percolate down, reducing friction and increasing glacial movement
Easily eroding rocks (e.g. sandstone or fractured rocks) are more prone to bed formation and warm based glaciers can reach great velocities when they move over degormable sediment

Question 11

How does Altitude impact glacier movement

Answer 11

Altitude affects precipitation and temperature
-greater precipitation in lower temperature, the greater the chance of suply of snow and ice and incease in mass balance
higher snowfall -> greater accumulations -> faster movement

Question 12

How does Gravity/Gradient impact glacier movement

Answer 12

Steeper gradient means less resistance to gravitational pull and therefore more movement

Question 13

ICE TEMPERATURE

Answer 13

in some environments e.g. Antarctica, its so cold that ice is frozen to bedrock. As a result the glacier moves more slowly, only moves by subglacial deformation. warmer temperatures allow meltwater to stay at rock-ice boundry, providing constant lubrication and increasing their speed

Question 14

Ice Thickness (size + mass)

Answer 14

Flow begins when ice exceeds about 50m of thickness. The greather the thickness the greater the pressure. PMP decreases and allows for more meltwater which reduces friction and increases the speed of the glacier
The heavier the ice the more force is needed to overcome increased friction and weight so speed may decrease

Question 15

Mass Balance:

Answer 15

Affects the equilibrium of the glacier and also whether it is advancing or retreating

Question 16

What processes occur in the glacial landform systems

Answer 16

Erosion,Plucking, Abrasion, Fracture and traction, Dilation, Meltwater and erosion, Entrainment, Transport, deposition

Question 17

Define glacial process of erosion

Answer 17

The removal of weathered material by glacial ice

Question 18

Define glacial process of plucking

Answer 18

Aka glacial quarrying: two-stage process, with the inital wideneing of the joints by the fracture and the subsequeny entrainment of any loosened material. the importance of plucking as a process is depndant on the rock type and incedence and pre-existing joints

Question 19

Define glacial process of Abrasion

Answer 19

individual clasts (stones) which leads to micro-features such as striations and chatter marks. Additionally rock floor polishes underlying rocks with as sandpaper action

Question 20

Define glacial process of Fracturea and traction

Answer 20

Occur as a result of the crushing effect of the weight of moving ice passing over the rock. Variations in pressure lead to freezing and thawing of meltwater (basal melting) which aids the plucking process

Question 21

Define glacial process of Dilation

Answer 21

occurs as overlying material is moved causing fractures in the rock parralel to erosion surfaces as the bedrock adjusts to the unloading

Question 22

Define glacial process of Meltwater erosion

Answer 22

can both be mechanical (sinilar to fluvial erosion, except that the water is under hydrostatic pressure) and chemical where by glacial meltwater can dissolve mineral and carry away the solutes, especially in lomestone rocks

Question 23

Define glacial process of Entrainment

Answer 23

small rock fragments are trapped (entrained) by basel ice freezing around them and applying sufficient drag to pull them along. They come fom supraglacial or subglacial processes.

Supraglacial: sources include material falling from hillsides being washed or blown onto the glacier from surrounding land, plus atmospheric fall out such as ash

Subglacial: sources include material eroded from the glacier bed and valley walls, material frozen to the base from the subglacial streams as well as englacial material that has worked its way down through the glacier or ice sheet

Question 24

Define glacial process of Transport

Answer 24

Rock debris are transported on the ice surface (supraglacial) within the ice (englacial) and at the base of the ice (subglacial)
Water as well as ice has an important role in the transporation of material. In temperate environments, water flows on top of glacier leading to a fluvial transport. This water may flow down crevasses or holes in the ice (moulins), and thus transport material into and beneath the glacier. Temperature glaciers also have meltwater streams flowing under the ice which carry material to the glaciers snout and beyond

Question 25

Define glacial process of deposition

Answer 25

The sediment deposited directly by glacial ice is called till. Fluvio-glacial debris are deposited by meltwater

Question 26

How do temperate and polar glaciers move

Answer 26

Temperate: Basal slip and internal deformation
Polar: Internal deformation

Question 27

Describe process of Basal slip

Answer 27

75% of glacier movement, Pressure reduces melting point and allows glacier to pass over obstacle

Enchanced basal creep and Reglation creep: obstacle causes increased pressure which makes ice plastically deform around the obstacle very slow, envoloping it. When ice moves over obstacle 1m> wide that increases localised pressure decreases pmp and causes meltwater to form which lubricates the ice and lets it move over the obstacle

Extensional and Compresional flow:

1) At valley of glacier the valley is steep so there is a strong gravitational force makin the ice move more quickly
2) When ice moves quickly theres more tension which causes the ice to fracture into layers, the layers slip downwards this is called extentional flow
3) Lower down the valley the gradient is less stepp making it move more slowly the faster ice from the further back pushes the slower ice down, compressing it
4) Higher pressure causes ice to fracture into layers which slip forwards, this is called compresional flow

Surges: In these short-lived events a glacier can advance substantially, moveing up to 100 times faster than normal, in Iceland it’s thought volcanic activity and seismic activity can lead to surges. Can also be caused by subglacial deformation: = When a glacier moves over a weak or unconsolidated rock, the meltwater mixes with the sediment to create conditions necessary for the sediment to deform under the weight of the glacier. locally this can account for 90% of glacial Ice’s forward motion-often in polythermal outlet glaciers as in Iceland

Question 28

Describe internal deformation

Answer 28

Estimated movement per day 1-2cm
-This occurs when the weight of the glacier ice and gravity causes the ice crystals to deform, so that the glacier moves downslope very slowly
Individual Ice crystals deform or fracture due to intense stress in ice as a result of weight of the glacier. Gradually the mass of the ice deforms and moves downhill in response to gravity
Where individual crystals slip and slide over each other

Question 29

Define Micro scale Landforms

Answer 29

-small landforms up to 1m long e.g. striations, glacial groove and chatter marks and erratics

Question 30

Define Meso-scale landforms

Answer 30

-Medium scale landforms e.g. roches mountonees, ribbon lakes, drumlins and kettle holes

Question 31

Define Macro scale landforms:

Answer 31

Lare scale landforms e.g. ice sheet eroded knock and lochan landscapes, cirques, glacial troughs and pyramidal peaks

Question 32

Define subglacial Environment

Answer 32

Environment beneath the glacier ice, subject to immense pressure from the overlying weight of ice; beaneath temperate glaciers there may be large volumes of meltwater

Question 33

Define Ice marginal Environment

Answer 33

Environments at the edge of the glacial ice where a combination of glacial and fluvioglacial processes occur

Question 34

Define pro-glacial Environment

Answer 34

Environments located at the front of a glacier, ice cap or ice sheet and dominated by fluvio-glacial processes

Question 35

Define periglacial Environment

Answer 35

Environments near glacier and dominated by freeze-thaw processes but not characterised by moving ice

Question 36

Define upland glacial Landscapes

Answer 36

Those at higher altitudes in hills and mountains

Question 37

Define lowland glacial Landscapes

Answer 37

Those at lower altitudes on valley floors and costal plains

Question 38

Define active glacial Landscapes

Answer 38

Currently experiance glaciation, active glacial processes and landform development

Question 39

Define relict glacial Landscapes

Answer 39

Are not currently characterised by glaciers but feature fossilised glacial landforms due to past glaciation

Question 40

Name the indirect erosional processes of erosion

Answer 40

Surface rotting
Pressure release
Plucking

Question 41

Name the direct proecsses of erosion

Answer 41

Crushing and fracturing

Abrasion

Question 42

describe the procces of surface rotting

Answer 42

Freeze thaw action occurs, cracks largen and scree builds up at the foot of the slope or fall onto the glacier to be transported by a moraine
Frost shattered rocks are very sharp and angular. As they become trapped under the ice, they form abrasive tools - like sandpaper.

Question 43

describe the procces of pressure release

Answer 43

Glacial advances and retreats constantly change the overburden pressures. Lots of material is made avaulable for subsequent advances

Question 44

describe the procces of quarrying

Answer 44

refreezing of meltwater freezes part of the underlying bedrock to hte base of the glacier. Loosened rock fragments are “plucked” away when the glacier moves forward. Process is particularly common when a reduction in pressure under the ice on the downslope side of an obstacle leads to the refreezing of meltwater

Question 45

describe the procces of Crushing and fracturing

Answer 45

Due to the sheer weight of the ice, matter is crushed and cracked by the ice

Question 46

describe the procces of Abrasion

Answer 46

debris carried by the glacier scrpaes and scratches (sand-paper effect) the glacial trough