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Geography > Glaciers > Flashcards

Glaciers Flashcards

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1
Q

What is plucking?

A
  • as the ice moves over the rock surface below, meltwater freezes around loose sections, pulling them away
  • this includes rocks being plucked away by the ice
  • increase in plucking increases abrasion
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2
Q

What is abrasion in ice erosion?

A
  • rocks and boulders embedded in the base of the glacier scratch and scrape the surface below
  • large boulders can scare the landscape with features called striations
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3
Q

What are striations?

A

-scratches of gouges cut into the base rock by abrasion

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4
Q

What is freeze-thaw weathering?

A
  • water (from rainfall or snowmelt) seeps into cracks in a rockface
  • temp falls at night causing water to freeze
  • water expands by 10% when it turns to ice therefore pressure increases causing the crack to widen
  • repetition of this process results in large boulders of rock shattered apart
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5
Q

Where is evidence of freeze-thaw found?

A

-scree slopes and blockfields

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6
Q

What are scree slopes and blockfields?

A

-piles of rock or debris that blanket large upland areas

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7
Q

How do glaciers move?

A
  • accumulation of snow in hollows is compressed into granules of ice
  • as the weight of ice accumulates, gravity causes it to flow over the lip and down the mountainside
  • surface of glacier cracks as the glacier moves over the uneven valley floor=crevasses
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8
Q

What is basal flow?

A

-when the glacier ice slides over the underlying rock on a film of meltwater

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9
Q

What is internal deformation?

A

-the ice at the base of the glacier moves, speeding up and slowing down in response to changes in gradient

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10
Q

What is ground moraine?

A

-large amounts of eroded rock fragments on the valley floor due to plucking and abrasion

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11
Q

What is the snout and what happens there?

A
  • end point of the glacier

- large amounts of meltwater pour off the snout and carry debris beyond

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12
Q

How does a glacier transport material?

A

-as the ice from upland areas descends into lowland areas, the snout bulldozes material
-soils, rocks and boulders are shoved forwards due to the huge force of the ice
-

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13
Q

Why is material carried inside the glacier?

A
  • plucking results in rocks being embedded in the glacier
  • some rocks fall in crevasses at the surface of the glacier. These crevasses can reach deep into the glacier resulting in the build up of material
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14
Q

What is glacial outwash?

A
  • sediment from the glacier carried in the meltwater river

- outwash becomes rounded due to attrition

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15
Q

What is a corrie?

A
  • large circular depressions in the rock
  • Glaciers start in them high up in the mountainside
  • typically filled with a lake called a tarn
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16
Q

How are corries formed?

A
  • -snow accumulates in a slight hollow, is compressed then turns to ice
  • ice mass slides downhill due to it’s weight
  • the back wall is made steeper by plucking, abrasion deepens the hollow
  • freeze-thaw happens at back wall of hollow resulting in it retreating
  • material deposited as moraine on the rock lip
  • after the ice age, ice has melted leaving it to be filled with a tarn
17
Q

What is an arete?

A

-two-sided, knife-edged peak found at the back of a corrie of separating 2 glaciated valleys

18
Q

How are aretes formed?

A

-due to freeze-thaw and the erosion of back to back corries by plucking

19
Q

What is a pyramidal peak?

A

-an angular sharply pointed mountain peak

20
Q

How is a pyramidal peak formed?

A
  • when 3 or more aretes meet back to back

- corries erode backwards towards each other and freeze thaw creates a sharply pointed summit

21
Q

What is a u-shaped valley or glacial trough?

A

-the once v-shaped valley is torn away by abrasion and plucking due to the glacier

22
Q

What is a hanging valley?

A

-a tributary valley with a floor at a higher relief than the main channel

23
Q

How is a hanging valley formed?

A
  • after glaciation, small rivers and u-shaped valley is left behind
  • tributary streams are left cascading down into the main valley and create waterfall
24
Q

What are truncated spurs?

A

-a former river valley spur which has been sliced off due to the moving valley glacier

25
Q

How are truncated spurs formed?

A

-Glacier slices off the spur due to the sheer force, leaving a flat-faced ridge called a truncated spur

26
Q

What is lateral moraine?

A

-material at the edges of the glacial trough

27
Q

What is ground moraine?

A

-material underneath the glacier

28
Q

What is medial moraine?

A

-when glaciers meet, 2 lateral moraines form together to become medial moraine

29
Q

What is terminal moraine?

A

-enormous ridge of material that gets bulldozed by the snout of the glacier

Geography (10 decks)

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