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GEOGRAPHY A LEVEL REVISION - LVI > Glaciated landscapes terminology > Flashcards

Glaciated landscapes terminology Flashcards

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1
Q

Arete

A
  • Sharp knife-edge ridge

- Where two corries meet

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2
Q

Abrasion

A
  • Type of erosion
  • Sediment at base erodes and smooths floor and sides
  • Sand-paper like
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3
Q

Bedload

A
  • Sediment dragged along the base of a glacier/ice sheet

- Erodes the ground beneath

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4
Q

Boulder clay

A
  • Aka till,
  • Mix of sands, clays, boulders
  • Deposited over a large area
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5
Q

Bulldozing

A
  • Material pushed forward by glacier
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6
Q

Calving

A
  • Ice blocks collapse and fall from the snout of the glacier, often into a glacial lagoon
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7
Q

Corrie

A
  • Armchair-shaped hollow
  • Formed through glacial erosion, rotational slip and freeze-thaw weathering.
  • Depression left when ice melts
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8
Q

Crevasse

A
  • Deep crack found in surface of an ice-sheet or glacier,

- Often buried under snow so can present a hazard

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9
Q

Drumlin

A
  • Deposition of glacial till as a glacier moves,
  • Half egg shaped
  • Long axis is parallel to direction of ice
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10
Q

Equilibrium line

A
  • Imaginary boundary

- Line between ablation zone and accumulation zone

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11
Q

Erosion

A
  • Material broken down and worn away

- Many ways e.g. abrasion, plucking, freeze-thaw

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12
Q

Erratics

A
  • Rock sediments transported and deposited by a glacier
  • Different geology to surroundings
  • Up to 3m across
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13
Q

Freeze-thaw weathering

A
  • Aka frost-shattering
  • Temperatures near freezing point
  • Water enters cracks in rocks, freezes, expand and then break rocks
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14
Q

Glacial trough

A
  • Aka glaciated valley or U-shaped valley,

- Deep, wide shape

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15
Q

Hanging valley

A
  • Tributary valley joins main glacier,
  • Too high/ cold for ice to easily move
  • Less eroded than main valley
  • It often has waterfalls today
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16
Q

Holocene

A
  • Current epoch of geological time
  • Began 12,000 years ago (end of Pleistocene)
  • Part of Quaternary period
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17
Q

Interglacial

A
  • Time between glacial periods (ice ages)

- Average temperature is higher

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18
Q

Lateral moraine

A
  • Narrow band of debris along sides of a glacier

- Ice erodes valley sides/freeze-thaw weathering

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19
Q

Moraine

A
  • Frost-shattered rock and eroded sediment

- Transported and deposited by glaciers

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20
Q

Outwash

A
  • Sediment deposited by meltwater streams in front of and underneath glaciers
  • Sorted and rounded over time,
  • Forms outwash plain
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21
Q

Plucking

A
  • Type of erosion

- Meltwater freezes onto rocks and ‘plucks’ and pulls off pieces of rock as ice moves

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22
Q

Pyramidal peak

A
  • 3 or more corries meet at a central point

- A steep pyramid shape

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23
Q

Ribbon lake

A
  • Long, narrow, finger-shaped lakes
  • Found in glaciated valleys
  • Where glacier had more erosion energy so over-eroded
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24
Q

Rouche moutonnées

A
  • A bare outcrop of rock shaped by erosion
  • One side smooth and gently sloping
  • Other side is steep, plucked and rough
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25
Q

Rotational slip

A
  • Ice flows in circular motion

- Erodes hollows and bowls in landscape

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26
Q

Scree

A
  • Loose stones broken away from mountain sides by freeze-thaw
  • Slopes covered in angular loose stones
27
Q

Snout

A
  • Aka terminus or toe
  • End of a glacier
  • Always advancing or retreating
28
Q

Tarn

A
  • Deep circular lake that forms within corries when ice has melted
29
Q

Terminal moraine

A
  • Ridge of rock debris deposited at the end of a glacier

- Mix of boulders, sand, gravel and clays

30
Q

Truncated spur

A
  • Former river valley spur where ends are ‘sliced’ off by a valley glacier
  • Steep cliff-like edges
31
Q

Weathering

A
  • Breakdown of material such as rock by physical (mechanical), chemical or biological processes
32
Q

Ablation

A
  • Ice loss from a glacier or ice sheet
  • Melting, sublimation, evaporation, ice calving, avalanche etc.
  • Ablation zone where net loss occurs
33
Q

Accumulation

A
  • Build-up of glacial mass

- Accumulation zone where there is net accumulation

34
Q

Albedo effect

A
  • Reflective capacity of material to return incoming solar radiation
  • White surfaces have high albedo effect
  • Feedback loop: if ice surfaces melt, more dark surfaces exposed, more rapid melting
35
Q

Basal sliding

A
  • High enough temperatures produce meltwater at base

- Water reduces friction between ice and bedrock

36
Q

Bergschrund

A
  • Deep crevasse along rear wall of a corrie

- Formed as ice moves away downhill

37
Q

Cold-based glaciers

A
  • Higher latitudes
  • Less seasonal variation in temperature, less meltwater
  • Moves by internal deformation
38
Q

Compressional flow

A
  • When gradient is less steep, or ice moves over a major obstacle, it slows down
  • Crevasses close, fractures form in ice
  • Thicker ice increases mass and pressure, eroding more
39
Q

Englacial moraine

A
  • Moraine carried in glacial ice
40
Q

Eskers

A
  • Long ridge of sediment deposited by meltwater from retreating ice
41
Q

Extensional flow

A
  • When the gradient becomes steeper, the ice accelerates
  • Ice stretches, becomes thinner
  • Cracks and crevasses created at 90º to flow
42
Q

Fluvioglacial

A
  • Term relating to erosion or deposition caused by flowing meltwater from glaciers or ice sheets
43
Q

Gelifluction

A
  • Form of solifluction in periglacial environments
  • Downslope sliding movement of seasonally thawed and saturated soil
  • Assisted by permafrost
44
Q

Glacial budget

A
  • Balance between inputs and outputs in glacial system

- Typically losses mass through evaporation and melting at snout

45
Q

Internal deformation

A
  • Mostly in cold-based glaciers
  • Gravity and pressure in accumulation zone causes crystals to slide over each other, crumple and deform
  • Can form crevasses
46
Q

Kames

A
  • Aka kame terraces
  • Steep-sided flat-topped mound of gravel and sand
  • Deposited by meltwater from retreating ice
  • Terrace forms when sediment accumulates in ponds and lakes
47
Q

Kettle holes

A
  • Rounded hollow filled by a lake, that forms due to a melting ice mass that is trapped within deposits
48
Q

Mass balance

A

The net change in a glacier’s mass over a year; this can be positive, if the glacier accumulates more mass than is lost through ablation, or negative, if there if more ablation that is accumulated

49
Q

Medial moraine

A

Weathered rock debris bands that run along the centre of a glacier, forming when lateral moraines from two glaciers merge together

50
Q

Misfit stream

A

Once all the ice has melted and a river returns to the deglaciated valley, it can look unexpectedly small in the scale of the wide glacial trough

51
Q

Moulin

A

A cylindrical vertical or near vertical shaft within a glacier, formed by surface meltwater percolating through a crack in the ice and scouring

52
Q

Needle ice

A

Another form of ground ice, with slice of ice that penetrate down through the soil vertically - crucial to breaking up soil particles to loosen them for erosion and transportation

53
Q

Nivation

A

A group of processes such as freeze-thaw and mass wasting serve to carve out depressions and hollows in the ground, which can enlarge over time to form corries

54
Q

Periglacial

A

An area adjacent to a glacier or ice sheet that is subjected to repeated freeze-thaw processes, a cold climate that commonly has permafrost, e.g. Canada, Greenland, Siberia

55
Q

Pingos

A

Hills that have an ice core, and are usually circular or dome-like in shape; the ice in the centre accumulates due to hydrostatic pressure or groundwater flow

56
Q

Pleistocene

A

The most recent epoch during which ice coverage was much greater than it is today, from approximately 2.5 million years ago until 11,800 years ago

57
Q

Recessional moraine

A

Similar to terminal moraine, and are deposited wherever the snout remained static for long enough to accumulate debris

58
Q

Rotational scouring

A

Layers of rock debris from the valley sides build up on the surface of the glaciers over time, and each successive winter it becomes embedded within the growing ice; bands of slowly rotating frozen rock then scrape over the bedrock to erode when ice moves downhill

59
Q

Solifluction

A

A process of gradually moving wet soil or other material down slope, particularly when frozen subsoil acts as a barrier to prevent percolation of water; a form of slow mass movement

60
Q

Striations

A

Grooves that are scratched into the bedrock below ice as the glacier moves and transports material down valley; these lines show in what direction the ice flowed

61
Q

Thermokarst

A

Irregular land surfaces found in periglacial landscapes that consist of alternating hills and hollows that are formed when permafrost thaws

62
Q

Till plains

A

When a large portion of ice becomes detached from the main glacier and melts, any suspended sediment within the ice will be deposited and form a large plain of unsorted till material

63
Q

Warm-based glaciers

A

Also known as temperate glaciers, these are found at lower latitudes; temperatures around the glacier are warmer allowing ice to move more rapidly with increased liquid meltwater and basal sliding e.g. The Alps, The Rockies

GEOGRAPHY A LEVEL REVISION - LVI (23 decks)

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