Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

INT D 280 - DONE > Lesson 6: Glaciers > Flashcards

Lesson 6: Glaciers Flashcards

1
Q

What is a glacier?

A

A mass of relatively slow-moving ice created by the long-term accumulation of snow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where do glaciers form?

A

They form wherever snow accumulation during the winter exceeds that which is removed by melting during the summer
-Key is the gradual build-up of successive annual layers of residual snow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Glaciers presently occupy ~ ___% of the world’s total land area with most in Polar Regions.

A

10%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Video:

Glaciers can be thought of as remnants of the last ice age. Describe.

A
  • Ended ~11,700 ya

- Ice covered over 30% of the planet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Video:

Glaciers in mountains suggest ice ages have occurred throughout the past ___ mys.

A

2 mys.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the glacier formation process.

A
  • Begins with the compaction of the surviving snow under a mass of new snow (density: 50-200 km/m^3). Expulsion of air from buried layers
  • Residual snow turns into firn after ~ 2 winters, intermediate state (density: 400 kg/m^3) (Video: 600-700)
  • Firn becomes glacier ice (density: 850). Remaining air trapped as bubbles locked in ice
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Video:

Describe the properties of fresh snow.

A
  • ~90% air

- Low density between 50-200 kg/m^3 (water is 1000)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does firn look like compared to glacier ice?

A

Firn: White with bubbles

Glacier ice: Blue, less bubbles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe sintering.

A
  • Snow crystals have complex shape with intricate arms
  • On ground, these structures come into contact; their arms connect and lock into place, leaving pore spaces between them
  • There is high pressure at the points of contact. Melting occurs first here
  • Melt water flows into spaces between crystals, where the pressure is lower and the freezing point is higher
  • Water refreezes, binding snow crystals together and enlarging individual grains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The process of glacier ice formation can be sped up with the introduction of ___.

A

Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does glacier ice form in “dry snow zones” (located at high elevations and in Polar Regions, where melting rarely occurs - too cold)?

A

Glaciers are formed through the mechanical breakdown of snow crystal, i.e. wind…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The speed at which glacier ice forms depends on what?

A
  1. Climate
  2. Range of air temperatures throughout the yr
  3. Amount of precipitation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How long does it take glacier ice to form in different environments?

A

Cold, dry places like Baffin Mountains of Canada E Arctic (little summer melting and low precip.): hundreds, even thousands of yrs
Warmer, like Coast Mountains of Canada W Coast (melting in summer and heavy snow fall in winter): 3-4 yrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are Ice Sheets?

A
  • Largest type of glaciers on planet, found today only in Antarctic and Greenland
  • Mass of glacier land ice extending more than 50,000 km^2
  • Flow independent of topography beneath
  • I.e. E and W Antarctic ice sheets, cover entire continent, submerge bedrock, separated by Trans Antarctic mountains, one of the longest chains in the world (almost completely covered in ice)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are Ice Caps?

A
  • Similar to ice sheets, but less than 50,000 km^2
  • Form primarily in polar and sub-polar regions that are usually high in elevation.
  • Also not constrained by topographical features
  • Dome lies on highest point of massif, also called ice divide where ice from towards the periphery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are mountain glaciers?

A
  • Broad category for various types of glaciers found in mountain regions.
  • All share one thing in common: ARE confined by the topography of the landscape in which they reside
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an icefield?

A
  • Largest type of mountain glacier
  • Ex, Columbia icefield, S Jasper National Park
  • Usually produce network of long glaciers that fall away from high basin and spill down valley (Valley/Outlet glaciers)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are Valley/Outlet glaciers?

A
  • Typically originate from an icefield
  • Ex. : Fedchenko glacier (Pamir Mountains of Tajikistan), extend 77 km and cover over 700 km^2, longest outside polar regions
  • Can be delineated into: Piedmont glaciers, Tidewater glaciers, Hanging glaciers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Video:

What is considered the hydrological apex of NA continent?

A

Columbia icefields in Canadian Rockies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a Piedmont glacier?

A
  • Occur when steep valley glaciers spill into relatively flat plains, fan out into bulb-like lobes
  • Ex, Malaspina glacier (SE Alaska), several valley glaciers spill out of St. Elias mountains onto coastal plain, 3900 km^3 (doesn’t reach water)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a Tidewater glacier?

A
  • Valley glaciers that flow far enough to reach out into sea
  • At sea, pieces break off (calve) to form small icebergs
  • Ex, Columbia glacier of Chugach mountains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are Hanging glaciers?

A
  • When major valley glacier system retreats and thins, sometimes tributary glaciers are left in smaller valleys high above shrunken central glacier surface
  • Often terminate at or near the top of cliff bands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are Cirque glaciers?

A
  • Smaller than valley glaciers
  • Isolated bowl-like hollows or basins they occupy
  • Found high on mountainsides and tend to be wider rather than longer
  • Can’t usually survive solely on accumulation of direct snowfall. Require avalanche deposits from surrounding rocks walls
  • Walls also provide shade, reducing direct solar radiation, limiting melting, and limiting size of glaciers (constraining to shaded area)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The various forms of mountain glaciers result from both…?

A
  • Topography
  • Climate
  • Because environmental conditions fluctuate, so do forms that glaciers assume
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the first known depiction of a glacier?

A
  • A 1601 watercolour depicting the Vernagtferner Glacier in W Austria
  • Shows formation of a glacier lake, which, because of outburst floods was a menace to down valley communities
26
Q

Video:

The English-speaking world of the 1600s knew little about mountain glaciers. When did they first begin to know of them?

A

1670s throughout royal society (England’s foremost intellectual institution)

27
Q

What is an example of Indigenous mountain cultures who had early sophisticated knowledge of glaciers and their dynamics?

A

E.g. NA First Nations people living on either side of the St. Elias Mountains came to know this glaciated landscape over successive generations

  • Tlingit on gulf coast of Alaska, inland Athabasca speakers
  • Reinforces vision that humans and nature make and mutually maintain the habitable world
28
Q

Glaciers only form when the amount of material/snowfall added in a given yr is greater than the amount removed. How is material primarily removed from the surface?

A
  • Surface melting
  • Evaporation
  • Calving
29
Q

Material added is referred to as the ___ ___; and material removed, the ___ ___. The difference between the 2 is called the ___ ___ ___.

A

Annual input and output.

Annual net balance/Mass balance

30
Q

What will a positive mass balance do? Negative?

A

Positive: glacier will grow and advance
Negative: glacier will shrink and retreat
-In a steady state, the mass balance over the course of a yr equals out (it achieves equilibrium), and glacier remains roughly same size

31
Q

Video:

Stable states maintain…?

A

Shape, Surface slope, and Thickness distribution of glacier

32
Q

What is the accumulation zone?

A
  • 1 of 2 main zones of glacier

- Higher, colder, snowfall occurs here in greatest quantity (inputs exceed outputs); annual mass balance is +

33
Q

What is the ablation zone?

A
  • 1 of 2 main zones of glacier

- Further down glacier, warmer, where outputs exceed inputs; here, the annual mass balance is -

34
Q

Between the two zones, a balance is reached where snowfall = snowmelt, and the glacier is in equilibrium. The average height where this occurs is called the ___ ___ ___.

A

Equilibrium line altitude (ELA)

35
Q

Where conditions favour glacier advance, the ELA tends to be relatively ___. Where conditions favour retreat, the ELA is relatively ___.

A

Low

High

36
Q

In a cooling climate (or where snowfall is increasing): The ELA ___, the accumulation zone ___ and the ablation zone ___ . Mass transfer from the accumulation zone by flow ___ and the glaciers ___ (the glacier’s terminus ___)

A
  • ELA lowers
  • Accumulations zone grows
  • Ablation zone shrinks
  • Mass transfer increases
  • Glacier grows
  • Terminus advances
37
Q

In a warming climate (or where melt increases): The ELA ___, the ablation zone ___ and the accumulation zone ___ , as the amount of snowfall that survives the yr is no longer sufficient to replace that removed from melting. The glacier develops a ___ mass balance that, if sustained, promotes glacial ___.

A
  • ELA rises
  • Ablation zone grows
  • Accumulation zone shrinks
  • Negative mass balance
  • Glacial retreat
38
Q

Video:

Who is Sveinn Palssen?

A

Icelander, 1794: first recorded observation that glaciers flow, climbed ice covered volcano and looking out onto outlet glacier notices bands now called Ogives

39
Q

What is basal sliding?

A

The slippage of ice en masse over the rock surface at its base (distinctive abrasions and striations on bedrock near the terminus of glaciers is evidence)

40
Q

What are the controls for basal sliding?

A
  1. Temp of ice at the base

2. Presence of water to serve as a lubricant

41
Q

Bed Deformation is a third mechanism that contributes to glacial flow. What is it?

A

Presence of water in bed surface that is not solid rock weakens bed. Glacier deforms sediment beneath it rather than simply moving on top of it.

42
Q

Flow rates due to ice deformation are relatively ___.

A

Constant.
Since driven by gravity, the thickness of ice, and slope angle; of all remain constant, so does flow rate.
Water introduced into system gives greater variability in flow rates

43
Q

Because of their dynamics, glaciers in the European Alps during the 1700s were a cause of great concern. Why?

A
  • Homes of dreaded creatures, e.g. Johann Scheuchzer’s Itinera alpine (1707) reported dragons)
  • Advancing glaciers in the W Alps had crushed the small French hamlet of Bonanay, near Chamonix (1644)
44
Q

During what time did the view on glaciers change and the discovery of an Ice Age occur?

A

During the 1800s.

45
Q

What is the “Little Ice Age”?

A

A short period (~1500-1850) when most of the world’s glaciers were actually advancing

46
Q

What is Compagnie des Guides de Chamonix (1821)?

A

Chamonix became so popular for its glaciers that a company was founded to regulate access to the slopes of Mont Blanc.

47
Q

How do crevasses form in glaciers?

A

-Due to tensional stress, so their distribution, size, and arrangement provide useful info on the flow behavior of the ice

48
Q

When do crevasses occur?

A
  • Most often when the middle and sides of glacier move at different rates
  • When ice curves around a bend or where slope steepens and rate of movement increases
  • At bumps or steps in bedrock
  • Usually transverse/horizontal to direction of flow, but can be oriented any direction
  • Largely restricted to surface, where ice is more brittle and fractures easily
49
Q

The presence of crevasses ___ the efficiency of rock transport.

A
  • Increases
  • Conveyer belt
  • Debris that falls into crevasses becomes incorporated into glacier and is often not seen until released at terminus
50
Q

Crevasses also ___ ablation.

A
  • Hasten

- Increase the glaciers surface area, pooling of meltwater, and disaggregating the ice near the terminus.

51
Q

What are snow bridges?

A

Bridges formed over crevasses by fresh snow.

52
Q

What are Moraines?

A

The noticeable linear accumulation of rocky debris oriented in the direction of the flow.
They’re created when the glacier pushes or carries rocky debris as it moves
I.e. Lateral and Medial

53
Q

How far down do moraines extend?

A

Deep into the ice, frequently all the way to the bottom.

54
Q

How do moraines affect mass balance?

A
  • Since the rock material is dark and can absorb more of the Sun’s E (hastening ablation), affects mass balance
  • Conversely, if big enough, it may act as insulated cover and inhibit the local melting of the underlying ice (ice-core moraines)
55
Q

Give an example of moraines.

A

Kaskawulsh glacier in kluane national park, St. Elias Mountains of Yukon.
-Convergence of 2 outlet glaciers, south and central arms

56
Q

What are some examples of glacial erosion?

A
  • Glaciated valleys: most readily visible glacial landform, trough shaped, steep, near vertical cliffs (sheared mountain sides), ex. Yosemite national park (CA sierra Nevada mountains)
  • Cirques
  • Arêtes: jagged narrow ridges where the back of two glaciers meet
  • Horns: several cirque glaciers erode mountain, sharp pointed peak, ex: Matterhorn in Switzerland (all 3 types glacial erosion)
57
Q

What is Headward erosion?

A

Erosion of upward origin of glacier, cutting back

-Ex. Cirque glaciers developing on opposite sides of a ridge erode headward and eventually form saddle or notch

58
Q 
Tech tip (Matt Peter):
How far apart should travellers be connected?
A

10-12 m

59
Q 
Tech tip (Matt Peter):
What are some equipment to stay safe while climbing?
A

Crampons (shoes with pick bottoms), harness, ice pick, anchor with ice screws, rock climbing hardware

60
Q 
Tech tip (Matt Peter):
For extremely steep climbing, what should you do?
A

Only 1 person climb at time, safeguarded with partner using belay or mechanical friction device (technical climbing)

61
Q

Geography exercise:

Lesson 6?

A
  • Mont Blanc (W Alps, France, Italy)
  • The Transantarctic Mountains (Antarctica)
  • The Columbia Glacier (Prince William Sound, Alaska US)
  • The Saint Elias Mountains (SW Alaska, SW Yukon and far NW BC)
  • The Vernagtferner Glacier (Tyrol, Western Austria)
  • The Matterhorn (Western Alps (Switzerland, Italy))
  • The Columbia Icefield (border of BC and AB)
  • The Baffin Mountains (Nunavut, Canada

INT D 280 - DONE (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions