glacier

Question 1

what are fluvioglacial landforms

Answer 1

those that are created by the work of meltwater streams in front of an often retreating glacier
created largely through deposition but also by erosion

Question 2

how does meltwater change glacial sediments

Answer 2

glacial deposits tend to be unstratified (have no layers)
meltwater changes the glacial sediment or till be sorting them by size, stratifying them into layers and rounding the sediments

Question 3

how does discharge and sediment load of meltwater streams vary

Answer 3

in summer discharges will be very high as meltwater arrives from many meltwater streams
in winter meltwater discharge may even stop as temperature may never rise above the pressure melting point
also varies on a daily basis, greatest discharges coinciding with highest daily temperatures

Question 4

where are contemporary fluvioglacial landscapes found

Answer 4

warm based glacial systems (for example in alpine regions)
in areas that tend to have meltwater (ones that have activity at lower elevations like valleys or outwash planes

Question 5

under what conditions will a glacier deposit materials

Answer 5

exceeding the carrying capacity - when the vector can no longer carry the material e.g. melting
losing energy: shrinking ~(not advancing) and change in relief (flat ground loses spread)

Question 6

what are erratics

Answer 6

glacier-transported rock fragment that differs from the local bedrock. Erratics may be embedded in till or occur on the ground surface and may range in size from pebbles to huge boulders weighing thousands of tonnes

Question 7

what is till

Answer 7

unsorted material deposited directly by ice (boulder clay)

Question 8

what is lodgement till

Answer 8

material lodged on the valley e.g. subglacial debris

Question 9

what is ablation till

Answer 9

combination of englacial and supraglacial debris, dropped in situ as the glacier begins to melt

Question 10

what is an outwash plain

Answer 10

Outwash plains are formed in front of a glacier and are where material is deposited over a wide area
the till levels out the landscape creating a characteristically flat topography

Question 11

what are moraines

Answer 11

a general term for unstratified and unsorted deposits of sediment that form through the direct action of, or contact with, glacier ice

Question 12

define a corrie

Answer 12

a deep hollow in a mountain side left behind by a glacier - characterised by a steep back wall and over deepened base

Question 13

define arête

Answer 13

a knife edge ridge separating two or more corries
e.g. striding edge, lake district

Question 14

define pyramidal peak

Answer 14

sharp summit and steep sides between 3 or more corries that have continuously eroded backwards

Question 15

what is a roche moutonnée

Answer 15

a mass of resistant rock which has a smooth, rounded up (stoss) slope facing against the direction of the ice flow and a steep, jagged face on the far (lee) side

Question 16

define glacial trough

Answer 16

also known as a u shaped valley
high, steep sided walls wis a flat, wide base
formed due to glaciers eroding the whole SA of valley much faster than the valley river

Question 17

define misfit stream

Answer 17

rivers in a glacial trough that did not erode to form the valley

Question 18

define hanging valley

Answer 18

remnants of river tributary valleys
smaller valleys that sit high on the sides of glacial troughs

Question 19

define truncated spur

Answer 19

former interlocking spurs that have been sawn off (truncated) by the glacier
end in an abrupt steep edge

Question 20

define ribbon lake

Answer 20

long and narrow lake found in a glacial trough
formation begins when a glacier moves over an area containing alternate sections of hard and soft rocks
soft rock is less resistant and erodes faster than hard rock, creating a rock basin, the hard rock acts as a dam where rain water accumulates

Question 21

define weathering

Answer 21

the breakdown of rock or parent material by external processes in situ

Question 22

what is physical/mechanical weathering

Answer 22

disintegration of rock without a chemical change
e.g. freeze thaw/exfoliation
often results in piles of angular rock fragments known as scree that can be found at the foot of a mountain

Question 23

what is chemical weathering

Answer 23

the decomposition of rocks caused by a chemical reaction with it e.g. acidic rainwater can react with and dissolve certain rocks and minerals

Question 24

what is biological weathering

Answer 24

involves the actions of flora and fauna e.g. plant roots expanding cracks in the rocks

Question 25

define mechanical weathering

Answer 25

creating a fragmented or angular landscape with loose material called scree

Question 26

what is freeze thaw/frost shattering

Answer 26

A crack in a rock can fill with water which then freezes as the temperature drops. As the ice expands, it pushes the crack apart, making it larger requires temperature fluctuation below and above freezing

Question 27

what is carbonation

Answer 27

the mixing of water with carbon dioxide to make carbonic acid

Question 28

what is nivation

Answer 28

an umbrella term used to cover a range of processes associated with patches of snow that result in the formation of hollows the collection of seasonal snow in hollows which encourage frost weathering beneath them

Question 29

describe the process of nivation

Answer 29

Snow and ice build-up on sheltered/shaded sloped areas. These patches often remain through the summer months. Compact névé snow can develop when snow melts and refreezes. Firn ice can develop over time in these shallow depressions, and when movement occurs, the ice can pluck small bits of loosened rock from the back surface of the area. Freeze-thaw cycles around the edges and below the snow patch cause frost shattering. When thawing occurs, the smaller pieces of frost shattered rock are moved down the slope by meltwater, solifluction and gelifluction. As a result of these processes, nivation hollows are formed, over time these can develop into corries.

Question 30

where are nivation processes most active

Answer 30

at the edges of snow patches because the exposed rock with low albedo absorbing more energy

Question 31

define abrasion

Answer 31

when rock fragments frozen to the glacier base smooth and sandpaper the bedrock as the glacier moves over it

Question 32

define plucking

Answer 32

as a glacier moves meltwater gets into cracks and freeze this rips or plucks out rock fragments from bedrock plucking can also occur on the headwall of a corrie, where the glacier is attached to the mountain

Question 33

define dynamic equilibrium

Answer 33

All natural systems are in this state state it means changing balance for glaciers, as inputs are constantly changing due to climate, the system needs to adjust to the changes in order to reach a new state of balance

Question 34

glacial budget

Answer 34

The balance between inputs and outputs the glacial budget is constantly changing the amount of ice in the glacier

Question 35

what is accumulation

Answer 35

inputs > outputs so glacier grows in size

Question 36

what is ablation

Answer 36

outputs > inputs so glacier will retreat and reduce in size

Question 37

what is a mass balance

Answer 37

accumulation - ablation positive balance accumulation > ablation negative balance ablation > accumulation

Question 38

what is net balance

Answer 38

annual mass balance of a glacier over a year a negative balance means the glacier snout is reterating a positive balance means that the glacier snout is advancing balance is a steady state or equilibrium

Question 39

describe the temporal variation in glacial budget

Answer 39

winter - positive balance = acculmulation = snout advance greater precipitation input reduced melting due to lower temperatures summer - negative balance = ablation = snout retreat reduced precipitation input increased melting, sublimation and calving due to raised temps moving faster, more energy, higher rates of erosion

Question 40

describe the spatial variation in glacial budget

Answer 40

ice caps/sheets: accumulation zone is in the centre ablation zone is in the periphery valley glaciers: accumulation zone - high altitudes ablation zone - snout

Question 41

what is humus

Answer 41

processed organic matter dead organic matter that has been broken down

Question 42

what is regolith

Answer 42

inorganic material and weathered down material (rocks) often helps with drainage

Question 43

what is biota

Answer 43

living plants and animals in soil

Question 44

what are adiabatic temperature changes

Answer 44

changing temp without adding or subtracting heat. result of compressing air or allowing allowing to expand

Question 45

what is the difference between isostatic and eustatic changes

Answer 45

Isostatic change is a local rise or fall in land levels. Eustatic change involves a rise or fall in water levels caused by a difference in the volume of water

Question 46

define a periglacial landscape

Answer 46

a landscape that undergoes seasonal freezing and thawing, typically on the fringes of past and present glaciated regions

Question 47

how does base temperature determine glacial movement

Answer 47

Warm based glaciers have a higher temperature at base than the pressure melting point this means that water that would've previously been frozen exists as liquid this leads to an increase in melt water which lubricates the base reducing friction and causes increased basal sliding a buildup of this meltwater can cause a surge (300m in a day) warmer temperatures also result in enhanced basal creep which is when an object in the path of the glacier causes increased pressure resulting in a higher PMP and therefore more meltwater In cold-based glaciers there is a lower temperature PMP so they do not experience as much basil sliding they move through internal defamation which is when the weight of the ice causes the ice crystals to stretch resulting in the downward motion of the glacier in some cold temperatures ice could freeze and attach to bedrock meaning subglacial internal deformation is the only force of movement cold temperature glaciers move much slower than warm temperatures

Question 48

what is the difference between ice creep and basal creep

Answer 48

Ice creep is when ice crystals slide past each other advancing the ice surface enhanced basal creep is the increased pressure from an obstacle in the path of the glacier leading to a low-pressure melting point and more meltwater ice creep happens everywhere whereas basal creep happens sub glacially

Question 49

where within the glacier is basal creep fastest

Answer 49

Ice cream happens fastest at the top/surface and the middle away from sides because there is the least friction with the sides and bedrock

Question 50

how does ice overcome obstacles

Answer 50

Through enhanced basal creep and basal slippage enhanced basal creep is caused by an obstacle which causes pressure whereras basal slippage is caused by increased pressure from ice and lower PMP so it travels more rapidly

Question 51

what is the difference between extending and compressing flow

Answer 51

extending flow is when a steeper gradient causes ice to move faster so the ice mass stretches becoming thinner compressional flow is where the gradient is less steep so the ice mass slows, backs up and crevasses close

Question 52

when will a surge occur

Answer 52

when excessive meltwater builds up at base and the glacier moves 300m in a day

Question 53

when and where does basal slippage occur

Answer 53

in temperate glaciers more frequent in summer

Question 54

how does bedrock permeability affect glacier speed

Answer 54

movement is faster over impermeable surfaces rather than permeable. This is because impermeable surfaces don't allow meltwater to escape and it stays at the base of the glacier. This decreases friction which allows the glacier to advance at faster rates

Question 55

what are the different kinds of permafrost

Answer 55

Continuous permafrost covers the largest areas with temperatures below -5°C Discontinuous permafrost occurs over smaller areas with temperatures between -5°C and -1.5°C Sporadic permafrost covers the smallest areas where temperatures are between -1.5°C and 0°C Permafrost can be classified as continuous (>90% of land area underlain by permafrost), discontinuous (90%-50%), sporadic (50%-10%)

Question 56

what is solifluction

Answer 56

the progressive movement of a mass down a slope caused by freeze-thaw activity

Question 57

define erosion

Answer 57

The wearing away and removal of rock by external agent

Question 58

define regelation

Answer 58

Regelation is the phenomenon of ice melting under pressure and refreezing when the pressure is reduced

Question 59

What are the names of the mechanical and chemical processes of subglacial melt water erosion

Answer 59

mechanical is fluvial abrasion Chemical is corrosion Corrosion is the process of slowly eating up metals by gas and water vapours present in the atmosphere due to the formation of certain compounds like oxide, sulphides, carbonate, etc

Question 60

define pressure release

Answer 60

aka dilation When the overlying mass is removed by weathering, the confining pressure decreases, allowing the rock to expand

Question 61

what is a rock step

Answer 61

outcrop or platform that is caused by a difference in type of rock hard/soft