glacial landscapes

Question 1

how can glacial landscaped be viewed as systems?

Answer 1

made up of components (stores) and processes (links) connected to make a working unit
store and transfer energy and material

Question 2

what is an open system?

Answer 2

energy and matter can be transferred from other systems as an input and transferred as an output.

Question 3

examples of input? x4

Answer 3

-kinetic energy from the wind and moving glaciers
-thermal energy from the heat of the sun
-potential energy from the position of material on slopes
-weathering and mass movement from slopes and ice from accumulated snowfall (avalanches)

Question 4

examples of output? x4

Answer 4

includes
-glacial and wind erosion from rock surfaces
-evaporation
-sublimation
-meltwater

Question 5

what are throughputs?

Answer 5

consists of stores; ice, water, debris accumulations and flows, including the movement of ice, water and debris downslope under gravity

Question 6

what is feedback in glaciated landscapes?

Answer 6

when inputs and outputs are equal, equilibrium exists within (snow added and lost at the same rate)

Question 7

What is dynamic equilibrium?

Answer 7

when the equilibrium is disturbed, the system goes under self regulation and changes from until the equilibrium is restored.
The system produced its own response to the disturbance, an example of negative feedback

Question 8

what is a glacier mass balance?

Answer 8

the difference between the amount of accumulation and ablation over a one year period in a glacier

Question 9

what is feedback?

Answer 9

in a system, an output which causes change to the inputs

Question 10

what is negative feedback?

Answer 10

one which reduces and possibly reverses the usual processes

Question 11

what is positive feedback?

Answer 11

one which exacerbates the usual processes

Question 12

how do you work out the net value of a site?

Answer 12

accumulation - ablation
if the answer is a negative value then the glacier retreated

Question 13

how does climate affect glacial landscape ; wind?

Answer 13

picks up material and uses it in the process of erosion, deposition and transportation - aeolian processes, contributing to shaping of glacial landscapes

Question 14

how does climate affect glacial landscape ; precipitation?

Answer 14

provides the main inputs of snow, sleet and rain
high latitude areas precipitation totals may be low
seasonal pattern can be varied, greater variation the more varied mass balance

Question 15

how does climate affect glacial landscape; temperature?

Answer 15

if temps rise above 0 the ice will melt
melting temp of ice decreases with an increasing pressure (pressure melting point)
affects input and output to the system in areas of high altitude temps may never rise above 0

Question 16

how does climate affect glacial landscape; altitude and latitude?

Answer 16

-high altitude glaciers have cold, dry climates with little seasonal variation. the higher the latitude, the more apparent this is.
-Glaciated landscapes at this latitude form under ice sheets
-lower latitude locations tend to have higher precipitation outputs, but more variable temps are more summer melting- move quicker

Question 17

how does the relief and aspect affect the glacial landscape?

Answer 17

the steeper the relief, the more resultant force of gravity, glacier moves downslope quicker
if the aspect of the slope faces away from the sun, less solar energy is received so temps remain below 0, less meltwater. Mass balance of glacier remains positive, glaciers advance and have greater erosional power.

Question 18

how does geology affect the glacial landscape; lithogy?

Answer 18

Some rock types such as clay have a weak lithology, and are easily eroded, weathered and have little resistance to mass movements. Bonds that make up rock particles are weak.
Other rocks eg basalt are more resistant and make prominent landforms eg pyramidal peaks
limestone is composed of calcium carbonate, soluble to weak acids so is vulnerable to decay by chemical processes eg carbonation espc at low temperatures

Question 19

how does geology affect the glacial landscapes ; structure?

Answer 19

permeability of rocks
eg chalk can store and absorb water - primary permeability
also includes angle dip of rocks as this can influence valley sides

Question 20

how is glacial ice formed?

Answer 20

• fresh snow has flakes w open flaky structure and a low density of about 0.05/cm3

-each new fall of snow compresses and compacts the layer causing low density to become high. Snow that survives one summer is known as firn and has a density of 0.4/cm3

-with further compaction by following snowfall, it becomes glaical ice with a density of between 0.83-0.91 g/cm3

-process known as diagenesis can take up to 30-40 years to occur

-characterised by being found 100m deep and blue not white

Question 21

what is diagenesis?

Answer 21

the process by which snow become glacial ice due to compression

Question 22

what is a valley glacier?

Answer 22

confined by valley sides
they may be outlets from ice sheets or fed from carries
they follow the course of the existing valley as they move downhill

Question 23

what is an ice sheet?

Answer 23

large accumulations of ice extending more 50,000 km2
there are currently two- Antarctica and Greenland

Question 24

what are warm based glacier characteristics?

Answer 24

also known as temperate/ alpine
-high altitude locations
-steep relief
-basal temperature at or above the pressure melting point
-rapid rates of movement, typically 20-200 m/yr

Question 25

what are cold based glacier characteristics?

Answer 25

also known as polar
-low altitude locations
-low relief
-basal temperatures the pressure points
-very slow rates of movement, a few meters/cm a year

Question 26

how do glaciers move?

Answer 26

-due to the forces of gravity
-ice moves downslope from higher to lower altitude
-in valley glaciers, this involves moving from the accumulation zone, across the equilibrium line and into the ablation zone

Question 27

what are the 5 factors that effect the movement of glaciers?

Answer 27

gravity - the fundamental cause of the movement of an ice mass

gradient - the steeper the gradient of the ground surface, the faster the ice will move if other factors are excluded

the thickness of ice - as this influences basal temperatures and the pressure melting point

the internal temp of ice - as they can allow movements of one area of ice relative to another

the glacial budget - a positive budget causes the glacier to advance

Question 28

how can ice move in different ways?

Answer 28

-when solid and rigid it will tend to break apart as shown by crevasses
-when under steady pressure it will deform and behave more like plastic

Question 29

what are the two zones in which glacial movements occur?

Answer 29

1. an upper zone where the ice is brittle and breaks
2. a lower zone where under pressure the ice deforms

Question 30

what did James Forbes conclude?

Answer 30

the sides and base of the glacier tended to move more slowly than the top and middle

Question 31

what are the reasons for James Forbes’ conclusion?

Answer 31

-ice may have been frozen onto the rocks of the valley floor and side
-obstructions that created frictional resistance & slowed down movement
-due to the accumulative effect of laminal flow in which each lower layer of ice not only moved itself, but carried the layers above it

Question 32

what is basal sliding?

Answer 32

the act of a glacier sliding over the bed due to meltwater under the ice acting as a lubricant

Question 33

what is slippage?

Answer 33

Where the ice slides over the valley floor as the meltwater has reduced friction between the glacier’s base and the valley floor.
Friction can also lead to to meltwater through the movement between ice and debris

Question 34

what is creep or relegation?

Answer 34

When ice deforms under pressure due to obstructions on the valley floor. This enables it to spread around and over the obstruction, like plastic, before re-freezing again when pressure is reduced

Question 35

what is bed deformation?

Answer 35

when the ice is carried by saturated bed sediments moving beneath it on gentle gradients
the water is under high pressure, this movement has been likened to the ice being carried on roller skates

Question 36

what is the Frank Josef glacier and how much does it move?

Answer 36

a warm-based glacier in New Zealand and moves approx 300m per year

Question 37

what % does basal sliding accounts for the movement of the salmon glacier

Answer 37

45% and 90% in extreme cases

Question 38

what is internal deformation?

Answer 38

Internal deformation occurs predominantly in cold glaciers where gravity and the pressure of ice in the accumulation zone causes ice crystals to slide over each other

it has 2 elements, inter granular flow and laminar flow

Question 39

what is inter-granular flow?

Answer 39

When individual ice crystals re-orientate and move in relation to each other

Question 40

what is laminar flow?

Answer 40

When there is movement of individual layers within the glacier, often layers of annual accumulation

Question 41

when does internal deformation occur?

Answer 41

both these movements occur when the glacier is on a slope, not on a level surfaces where the ice remains intact

Question 42

what is extending flow?

Answer 42

It is when ice moves over a steep slope and it is unable to deform quickly enough so fractures and creates crevasses. The leading ice pulls away from the ice behind it which has yet to reach the steeper slope

Question 43

what happens when the gradient is reduced?

Answer 43

compressing flow occurs as the ice thickens and the following ice pushes over the slower-moving ice

Question 44

what are slip planes?

Answer 44

the planes of movement are at different angles in each case

Question 45

why do some glaciers surge occasionally?

Answer 45

some glaciers may surge occasionally surge at rates of 100m per day
only likely on relatively steep gradients in warm based glaciers after large inputs of snow and ice have been received

Question 46

what are some surges triggered by?

Answer 46

tectonic activity such as earthquakes

Question 47

where are warm based glaciers found and what effect does this have?

Answer 47

-alps and the rockies
-experience high rates of accumulation in the winter, due to significantly warmer above zero temps
-high rates of ablation in the summer
-glacier in this region are very active with large volumes of ice being transferred across the firn line and significant seasonal retreat
-erosional landforms occur but due to the large amount of outputs from the glacial system landforms of fluvioglacial deposition are common

Question 48

where are cold based glaciers found and what effect does this have?

Answer 48

-antartica and greenland
-summer temps are below freezing & precipitation is low, both accumulations and ablation are limited & no great seasonal difference
-not very dynamic, little moment and limited landscape impact as well: little erosion, deposition and transportation take place

Question 49

what is the main difference between warm and cold based glaciers?

Answer 49

the main difference between warm and cold based glaciers is their basal temperature and its relationship with the pressure melting point.

Question 50

what is compressing flow?

Answer 50

the movement of glacial ice down a gentle gradient, during which it thickens.

Question 51

what is pressure release?

Answer 51

when the weight of the overlying ice in a glacier is lost due to melting, the underlying rock expands and fractures parallel to the surface.

Question 52

define a glacial landscape

Answer 52

glaciated landscapes are those parts of the Earth’s surface that have been shaped, at least in part by the action of glaciers.

Question 53

what is a system?

Answer 53

a system is a set of interrelated objects comprising components (stores) and processes (links) that are connected together to form a working unit or a unified whole.

Question 54

where is the accumulation zone?

Answer 54

upper areas of the glacier

Question 55

where is the ablation zone?

Answer 55

lower areas of the glacier

Question 56

what divides the ablation and accumulation zone?

Answer 56

equilibrium line