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Earth sci > Module 8 > Flashcards

Module 8 Flashcards

Glaciers

1
Q

how does ice form

A

snow accumulates, compacts, melts, and refreezes - changes into firn. the firn the compacts, melts and refreezes further and transforms into ice

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2
Q

firn

A

snow which has survived a summer melt season and has begun to change into ice

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3
Q

how do glaciers form on Mars

A

ice in the polar latitudes turns into water vapour when the tilt of the axis is high and wind transports it to a lower latitude. The vapour then deposits ice on the surface and the higher humidity moves surface ice stability region towards the equator. ice persists and accumulates

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4
Q

what makes glaciers move

A

gravity. they move in response to stress

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5
Q

movement or deformation of ice

A

strain

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6
Q

how quickly does glacier ice move

A

3 - 300m/year

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7
Q

what determines how quickly ice moves

A

slope of the glacier, ice thickness, temperature, valley geometry, bedrock conditions, and subglacial hydrology

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8
Q

how do glaciers move

A

basal sliding, internal deformation, and crevassing

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9
Q

basal sliding

A

requires water at the base so that it can slide over it. need “warm” ice so that a thin layer of it melts

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10
Q

example of basal sliding

A

Alaska, Rockies

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11
Q

internal deformation

A

ice deforms as a plastic material

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12
Q

crevassing

A

upper surface of ice is brittle, so fractures or crevasses form to allow movement

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13
Q

where are the fastest glaciers

A

“warm” ice where temp is close to 0. Alaska, Rockies

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14
Q

example of crevassing

A

Klutlan Glacier - Alaska/Yukon

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15
Q

where are the slowest glaciers

A

“cold” ice. Antarctica

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16
Q

where in a glacier does ice move the fastest

A

in the centre at the top

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17
Q

ogives

A

dirt bands in ice that show differential movement

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18
Q

why do glaciers move slower on the sides and at the bottom

A

friction from the surface below and beside them

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19
Q

glacier budgets

A

relationship between gain and loss of mass

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20
Q

positive budget

A

more mass gained than lost. glacier terminus will advance

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21
Q

negative budget

A

more mass lost than gained. glacier terminus will retreat

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22
Q

where is mass gained

A

accumulation area

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23
Q

where is mass lost

A

ablation (wastage) area

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24
Q

equilibrium line (snow line)

A

point on the glacier where there is neither gain or loss of mass

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25
Q

ice flow

A

flows from the accumulation area to the ablation area. NEVER FLOWS BACKWARDS

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26
Q

what does increased melt mean

A

ice front has retreated

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27
Q

example of ice front retreat

A

South Cascade Glacier, Washington

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28
Q

what is science showing about glacier budgets

A

lost more mass then they gained - negative mass balance because of climate change

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29
Q

moraines

A

landforms generated at the margins of glaciers from sediments carried down

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30
Q

large latero-frontal moraines

A

steep-sided, often ice-cored, prone to slope failure

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31
Q

what can latero-frontal moraines do

A

form significant barriers to drainage. creates impound lakes receiving glacial meltwater

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32
Q

what happens if the barrier/dam of a latero-frontal moraine is breached/overtopped

A

glacial lake outburst flood (GLOFs) released - extremely dangerous

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33
Q

example of latero-frontal morain impound lake

A

Lake Paron, Cordillera Blanca, Peru

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34
Q

continental ice sheet size

A

> 50,000 km^2

35
Q

two continental ice sheets

A

Antarctic and Greenland

36
Q

ice cap size

A

<50,000 km^2

37
Q

where are ice caps found

A

often in mountainous areas

38
Q

examples of ice caps

A

Iceland, and Southern Patagonian Ice Field

39
Q

outlet glacier

A

radiate from the edge of an ice cap

40
Q

example of outlet glacier

A

Iceland

41
Q

valley glaciers

A

flow in bedrock valleys - valley with glacier ice flowing through it

42
Q

example of valley glacier

A

Athabasca glacier

43
Q

piedmont glaciers

A

valley glaciers that extend out onto lowlands, and open up when they flow out

44
Q

example of piedmont glaciers

A

Malaspina glacier Alaska, Canadian Arctic

45
Q

which type of glacier is a good analogue for Mars

A

piedmont glaciers

46
Q

cirque glaciers

A

occupy small, semi-circular hollows in mountainous regions

47
Q

examples of cirque glaciers

A

Rockies, Alps

48
Q

ice shelf

A

floating part of an ice sheet or ice cap. glacier ice is connected to main mass but then extended out to sea. made of fresh water.

49
Q

example of ice shelf

A

Ross Ice shelf, Antarctica

50
Q

erosion

A

takes stuff from a surface

51
Q

deposition

A

leaves stuff on the surface

52
Q

where does erosion take place

A

at the base. clean ice does not erode - need abrasive debris

53
Q

how does debris get into ice

A

entrained by freezing, then forms a thin basal debris zone

54
Q

how does ice erode

A

abrasion.

55
Q

abrasion

A

debris in ice dragged across substrate at the base of a glacier, which forms striations and smoothes rock

56
Q

what kindof landforms are created by abrasion

A

smoothed and streamlined landforms of bedrock - not loose material

57
Q

what does abrasion do to the debris carried in the ice

A

shapes stones (faceting), reduces grain sizes, and produces lots of silt

58
Q

how else do glaciers erode

A

plucking

59
Q

plucking

A

debris is released by the fracturing of bedrock from water seeping in. the water then mechanically breaks up the bedrock and fragments are plucked by the glacier

60
Q

examples of landforms created by abrasion

A

rouche moutonee, whalebacks

61
Q

example of cirques/corries

A

Norway, Olympic National Park

62
Q

landforms of glacial erosion

A

chatter marks, striations, cirques, horns

63
Q

corries/cirques

A

semi-circular erosional “hollows”

64
Q

Horns

A

remnant peak of mountain

65
Q

arete

A

narrow erosional ridge

66
Q

glacial troughs

A

u shaped valleys

67
Q

fjords

A

flooded valleys

68
Q

glacial deposition

A

deposit debris in a range of settings: subglacial, supraglacial, proglacial, and glaciolacustrine

69
Q

subglacial deposits

A

debris in the base of ice smeared onto substrate. forms lodgement till.

70
Q

subglacial landforms

A

lodgement till plain that is made at the base of the ice. streamlines forms parallel to ice flow with drumlins and flutes

71
Q

drumlins

A

half egg-shaped hills made of till (may contain sand or bedrock) formed at the base of ice. creates a basket of eggs topigraphy

72
Q

example of drumlin field

A

Peterborough drumlin field

73
Q

flutes

A

long narrow ridges made of till. The till was squeezed into linear cavities at the base of the ice

74
Q

examples of flutes

A

Saskatchewan Glacier, Iceland.

75
Q

ice marginal landforms

A

transverse to ice flow. push ridges. created by advance of the ice front in the winter

76
Q

supraglacial deposits

A

forms lateral and medial moraines on glaciers

77
Q

how does debris get onto glacial ice

A

rockfall debris from valley walls

78
Q

supraglacial landforms

A

ice melts slowly from under supraglacial debris and forms kettle holes, producing irregular, hummocky, topagrophy

79
Q

example of supraglacial landforms

A

dundas valley

80
Q

what supraglacial landforms are potentially on Mars

A

Hummocks

81
Q

Glaciolacustrine deposits

A

Lakes on the margins of glaciers that are fed by meltwater

82
Q

kinds of sediments deposited in glacial lakes

A

sands and gravels deposited on deltas. silts and clays carried into a lake that slowly settle out from suspension and form laminated fine-grained deposits

83
Q

what can carry sediments into lakes

A

icebergs carrying coarse debris which then melts out of the ice

Earth sci (6 decks)

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