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Glacial Geomorphology > Introduction to Glaciers > Flashcards

Introduction to Glaciers Flashcards

1
Q

Glaciers cover how much of the planet?

A

10%

Arctic, Antarctic and Himilayas

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2
Q

An important source of…

A

Freshwater supply and water generation
Norway 98% of energy is from HEP- 15% of which comes from glacial catchments.
1 billion people live in the vicinity of the Himalayas- freshwater during the dry season.

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3
Q

The last ice age

A

Ended around 100 years ago

Covered around 30% of planet

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4
Q

Snowball earth

A

Entire earth covered in glaciers

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5
Q

Why are glaciers important in energy supply?

A

If the volume of ice changes so does the power distribution

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6
Q

Where do we find glaciers generally?

A

High latitude places
High elevation places
E.g Alps, Scandanavia

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7
Q

In order to have a glacier we need…

A

Snow on a mountain that’s going to survive summer.

Built up over years and snow will form ice.

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8
Q

Meltwater from the Himalayas flows into rivers that how many people rely on?

A

Over 1 billion people rely on for irrigation, livelihood,

power generation…

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9
Q

What basins are most susceptible to reductions of flow?

A

The Brahmaputra and Indus basins are most
susceptible to reductions of flow, threatening the food
security of an estimated 60 million people

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10
Q

Glacial hazards

As glaciers retreat…

A

…Moraines can dam meltwater creating a lake

If these lakes breach then can cause catastrophic floods

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11
Q

How to make a glacier?

A

Snow falling

As weight increases (compacted) = squeezing out air = ice crystals

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12
Q

What is a positive mass balance?

A

If a glacier is growing it has a positive mass balance

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13
Q

What is a negative mass balance?

A

If a glacier is shrinking then it has a negative mass

balance

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14
Q

What is the Equilibrium Line Altitude (ELA)?

A

Altitude on the glacier where the mass balance is zero is

called the Equilibrium Line Altitude (ELA)

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15
Q

What can be measured by field measurements?

A

Glacier hydrology
Glacier mass balance
Glacier meteorology

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16
Q

What can be measured by remote sensing?

A

Glacier surface

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17
Q

Glacier types

Cirque Glacier

A

– Formed in a cirque (bowl shaped depression)

– Significant accumulation from avalanching

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18
Q

Glacier types

Valley glacier

A

– Flow from the higher accumulation areas down to lower lying ablation areas
- Creator of fjords

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19
Q

Glacier types

Piedmont glacier

A

– Occur when steep valley glaciers spill into

relatively flat plains

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20
Q

Glacier types

Ice caps

A

– Defined either as a domed shaped mass of glacier
ice that does not completely cover the topography
– …OR < 50,000 km2

21
Q

Glacier types

Ice sheets

A

– Defined either as a domed shaped mass of glacier
ice that completely covers the topography
– …OR > 50,000 km2
– Currently only Antarctica and Greenland, but paleo
examples exist

22
Q

Glacier types

Crevasses

A

– reflect stresses imposed on the glacier by the valley sides
- water can melt its way down and ice can go all the way to the bed

23
Q

Glacier types

Ogives

A

“Bands” on the glacier surface
– Light bands reflect the “clean” ice that passed over the ice fall in the winter
– Dark bands reflect the “dirty” ice that passed over the ice fall in the summer

24
Q

What is clean ice?

A

Clean ice with almost nothing on it

25
Q

What is debris ice?

A

If there are lots of monsoon action, avalanche, debris flows (material covering it).
Hard to tell ice is there.

26
Q

What 3 ways can glaciers flow?

A

1) Creep (internal deformation)
2) Sliding
3) Deformation

27
Q

Glacier flow

1) Creep (internal deformation)

A

Ice is a semi-viscous material and moves under its own weight.
This is when the ice is completely frozen, and the only way it will move is it will slowly deform.

28
Q

Glacier flow

2) Sliding

A

Sliding on meltwater

If we have water on the bed, from either melt flowing down or volcanoes melting from beneath, this will cause the glacier to flow quicker.

29
Q

Glacier flow

3) Deformation

A

The sediments deforming- if we have lots of soft sediments underlying these can deform (especially in water) and the ice can slide on these sediments.

30
Q

What is geothermal heat?

A

Heat coming from the bottom of the ice.

31
Q

How are glacial landforms made?

A

If heat is enough to melt the ice then we have water.

The ice slides on the water and carves the rock.

32
Q

What is pressure melting point?

A

The temperature that ice freezes depends
on pressure:
– 0oC - atmospheric pressure
– Increases with pressure - 0.072oC per 106 pascals

33
Q

What are cold-based Glaciers?

A

Entire glacier bed is below the pressure melting point
Entirely frozen
Only move by internal deformation (creep)

34
Q

What are warm-based Glaciers?

A

Above the pressure melting point
Meltwater at the bed
Move by internal deformation, sediment deformation and basal sliding

35
Q

What are polythermal Glaciers?

A

Areas where the ice is frozen higher up

Areas where ice is flowing on water lower down

36
Q

What is supraglacial transport?

A

On top of the glacier surface

37
Q

What two landforms does supraglacial transport create?

A

Lateral moraine

Medial moraine

38
Q

What is a lateral moraine?

A

Parallel ridges of debris (from rock falls and debris slides)
deposited along the sides of a glacier

39
Q

What is a medial moraine?

A

When two lateral moraines meet at a glacier confluence

40
Q

What is englacial transport?

A

Where, in the summer, when there is a lot of water it will flow through the glacier.
Channels form.

41
Q

What is subglacial transport?

A

Sediment being transported at the bottom of the ice.

42
Q

What kinds of glacial erosion?

A

Abrasion
Plucking
Meltwater erosion

43
Q

What is abrasion?

A

Sandpaper like erosion from rocks and stones engrained in the ice
Leaves behind polished surfaces with striations and rock flour
Factor of amount of/hardness of rock, pressure, velocity of glacier and presence of meltwater

44
Q

What is plucking?

A

Dislodging and removal of rocks and boulders on the lee side of slopes
Leaves behind jagged landscapes

45
Q

What is meltwater erosion?

A

Loosening, dissolving, and removing rock/debris
Water often at a very high pressure and carrying sediment
Large amounts of meltwater can increase sliding = further erosion

46
Q

Scales of Glacial Erosion Landforms

A

Small – Striations, fractures

Medium– Roche montonee

Large– Cirques, troughs, arêtes and pyramidal
peaks

47
Q

V shaped valleys are from…

A

Fluvial erosion

48
Q

U shaped valleys are from…

A

Glacial erosion

Glacial Geomorphology (2 decks)

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