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Geography > Cold Environments > Flashcards

Cold Environments Flashcards

1
Q

(Fluvio)

Why is meltwater important?

A
  • erodes nivation hollows
  • lubricates the ground so the glacier can move forward periodically
  • binds rock to the glacier if it refreezes
  • forms rivers above and below the glacier
  • erodes channels and forms depositional features
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2
Q

What is a fluvioglacial land form?

A

A landform created by meltwater.

it is mostly as a result of deposition, but there is also some erosion.

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3
Q

(Fluvio)

What is a warm based glacier?

A

A glacier outside of Antarctica that has a lot of meltwater present. It moves between 20 - 200 m pa, so is more likely to erode, deposit and transport material.

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4
Q

What is a cold based glacier?

A

They occur near the poles where temperatures are much colder.
They remain frozen year round, so there is little movement, deposition, transportation or erosion.

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5
Q

What is internal flow?

A

The movement of a glacier due to gravity.
surface ice moves fast, causing crevasses to form.
can occur in both warm and cold based, though mostly in cold.

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6
Q

what is basal slippage/flow?

A

Large chunks of ice move in jerky movements.
As the glacier moves it creates friction, causing ice to melt, which lubricates the flow of the glacier causing it to move faster.
occurs in warm based glaciers.

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7
Q

What are the types of basal flow?

A

Regelation slip

Creep

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8
Q

What is regelation slip?

A

when a glacier meets an obstacle, there is pressure on the up glacial side. this causes ice to melt, lubricating the flow over the ice.
it refreezes in the down glacial side where there is little pressure.

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9
Q

What is creep?

A

when stress builds up within the glacier, the glacier becomes plastic and flows.
this tends to occur at a large obstacle

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10
Q

6 factors that control the flow of ice

A 
Gravity
Friction
The mass of the ice
Melt water
The temperature of the ice
Geology
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11
Q

What is extensional flow?

A

the ice flows faster, thinning out. This can cause crevasses to form. Thinner ice = less erosion.

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12
Q

Where does extensional flow occur?

A

occurs above the firn line where the up valley ice meets the down valley ice, or where the slope steepens.

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13
Q

What is compressional flow?

A

the slope changes, the glacier slows down causing ice to ‘pile up’ and thicken
any crevasses are closed
the ice has greater erosive power as it is thicker

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14
Q

Where does compressional flow occur?

A

where the up valley ice meets the down valley ice, pushing against it

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15
Q

What is rotational flow?

A

Between zones of extensional flow and compressional flow, the ice moves in a curved manner.
this can occur in a corrie, around a central point of rotation.

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16
Q

What is a glacial surge?

A

In cold environments, when there is an unusual amount of summer melting, the meltwater lubricates the rock allowing for a sudden and rapid downhill movement.

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17
Q

Where is the fastest flow of ice?

A

In the centre of the glacier where there is least amount of friction.

18
Q

Give one way in which crevasses can form?

A

When the surface ice flows faster than the base and side ice
OR
where the valley widens
OR
when a glacier flows from a valley onto a plain

19
Q

What is a piedmont glacier?

A

When a glacier flows from the valley onto a plain

20
Q

What is weathering?

A

The break down of rocks in situ

21
Q

What are two agents of weathering?

A

Wind and rain

22
Q

What is freeze thaw weathering/ frost shattering?

A

Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.

23
Q

Define abrasian

A

when angular material wears away the base and sides of the valley
finer material smooths, larger material leaves grooves called striations

24
Q

Define plucking

A

when a glacier freezes into outcrops in the valley floor and sides, and them moves away pulling the outcrops with them leaving a jagged surface

25
Q

Define Nivation

A

when snow builds up and freeze thaw action and chemical weathering occur underneath it.

26
Q

Supraglacial debris

A

material carried on the glacier

27
Q

englacial debris

A

material carried within the glacier

28
Q

subglaciel debris

A

material carried beneath ice

29
Q

Till

A

all material deposited directly by the ice, tends to be unsorted

30
Q

Fluvioglacial material

A

sediments deposited by melt water streams,

tends to be sorted, with sediments becoming finer away from the glacier snout

31
Q

Subglacial streams

A

under a high pressure so has a high velocity, turbulent flow
great power of erosion (valleys can be eroded 15m)
can carry a large load
when discharge decreases, the load is deposited (heaviest first) resulting in the sorting of the load

32
Q

outwash plains

A

an area of sands and gravels that gently slopes

33
Q

how are outwash plains formed?

A

by the deposition of debris from streams leaving the snout of the glacier
the heaviest materials are deposited first
the plain is layered, reflecting the seasonal deposition of material (more meltwater in summer means material can be carried further before being deposited, so there is a layer of coarser material)

34
Q

Eskers

A

long, sinuous ridges of sorted material that run in the direction of ice flow. they are often layered

35
Q

how are eskers formed?

A

subglacial streams beneath the glacier had a large load due to hydrostatic pressure. deposition of the load during the melting of the glacier. this leads to mounds that can reach 30m in height.

36
Q

Kames

A

Deposits of sorted and often stratified sand and gravel left by meltwater along the front of a melting ice sheet.

37
Q

Kame Terrace

A

Long and continuous bench like terraces that are formed when a gap between the ice and valley wall is filled with fluvioglacial deposits.
When the ice melts they are left as a ridge on the valley wall.

38
Q

Kame Delta

A

When a stream deposits material when entering a marginal lake. They form small, mound like hills on the valley floor and can be identified by their sediment characteristics.

39
Q

Crevasse Kame

A

The fluvial deposition of sediments in surface crevasses. When the ice melts they are deposited on the valley floor to form small hummocks.

40
Q

Braided streams

A

Streams crossing outwash plains are braided. The channels become choked with sediments during seasonal variations in discharge, causing the channel to find alternate routes.

41
Q

Kettle Holes

A

Depressions often filled with lakes or marshes and found on outwash plains.
Formed by large blocks of ice being covered by fluvial deposits, then melting causing the deposited sediment to slump and form a depression.
It then can fill with melt water to form a kettle lake

Geography (1 decks)

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