Glaciers & climate change

Question 1

Why were Vikings particularly prolific from 800-1200 A.D.?

Answer 1

Warm temperatures enabled them to travel freely and inhabit Arctic lands

Question 2

Glacial drift

Answer 2

Large rocks found far from the sources, this hindered cultivation for farmers. They were found in large valleys.

Question 3

Erratics

Answer 3

the glacier left behind single rocks, no strata and no order

Question 4

Louis Agassiz

Answer 4

paleontologist that measured glaciers

Question 5

Interpretations of glacial drift

Answer 5

1. great deluge (flood)

2. glacial origin

Question 6

Agassiz notes about glaciers

Answer 6

1. can carry large boulders
2. do not sort sediment
3. melt and leave behind deposits

Question 7

How have glaciers affected us here in western Oregon?

Answer 7

Floods triggered by the failure of glacial dams in Montana swept down the Willamette valley and into the Eugene area

Question 8

Transformation to glacial ice:

Answer 8

1. accumulation and compaction
   2 initial snow- 90%
   3 ends blunted by melting or sublimation 50% air
   4 with overburden, pressure melting
   5 firm snow packed- 25% air
   6 water recrystallizes in voids - 20% air
   7 glacial ice is not transparent because of air bubbles- bluish color

Question 9

two types of glaciers

Answer 9

alpine and continental

Question 10

Alpine glaciers

Answer 10

• occurs in mountainous areas

- topographic control on ice movements

Question 11

continental

Answer 11

-spreads over large areas
-unconfined by topography
-thick
today found in Antartica and green land

Question 12

why isn’t the north pole capped by an ice sheet?

Answer 12

there is no land to have an ice sheet on. spreads on the ocean.

Question 13

Glacier requirements

Answer 13

1. Cold- snow doesnt melt in the summer
2. snowfall- accumulation
3. gentle surface slope- accumulation without avalanches

Question 14

what controls temperature?

Answer 14

altitude and latitude

Question 15

Altitude

Answer 15

temperature decreases with elevation

Question 16

Latitude

Answer 16

distance from the equator

Question 17

result of latitude and altitude

Answer 17

glaciers are closer to sealevel near the poles

Question 18

Viscosity

Answer 18

the measure of a material’s resistance to flow

Question 19

Styles of glacier movement

Answer 19

1. Basal sliding
2. Internal flow
3. Fracturing
4. Plastic flow

Question 20

Basal Sliding

Answer 20

• Meltwater accumulates at base of glacier
• Fluid pressure reduces friction
• Common in temperate glaciers (warm areas)

Question 21

Mechanisms of basal sliding

Answer 21

Regelation: on up-glacier side of obstructions, pressure melting occurs
- on down-glacier side, water refreezes

Question 22

Internal Flow

Answer 22

• Plastic like flow
• ice crystals deform
• shearing- crystals slide past one another
• polar glaciers - base frozen to ground

Question 23

Fracturing

Answer 23

• Brittle behavior
• ice near surface (upper 60m)
• crevasses

Question 24

Plastic flow

Answer 24

• below 60m depth

- Deformation is pressure dependent

Question 25

why dont glaciers flow downhill faster?

Answer 25

Sediment at their beds slow them down

Question 26

two general factors of the rate of movement

Answer 26

1. slope | 2. ice thickness

Question 27

Water is a big factor in the rate of movement

Answer 27

Temperate glaciers are faster than polar ones

Question 28

Surges

Answer 28

- Build up of water pressure - short term acceleration - water drainage slows it down - velocities 20-100 m/day

Question 29

movement driven by gravity

Answer 29

1. sloping surfaces (valley glacier) 2. gravitational spreading - flat pressure builds with thickness - lateral movement releases pressure

Question 30

Accumulation by snowfall

Answer 30

- upper portion of glacier | - winter snow doesnt melt

Question 31

Ablation

Answer 31

loss of ice near the base of glacier - sublimation - melting - calving

Question 32

Equilibrium Line

Answer 32

seperates accumulation and ablation zones

Question 33

Negative budget

Answer 33

- ablation exceeds accumulation | - glacier retreats

Question 34

Positive budget

Answer 34

Accumulation exceeds ablation | -glacier advances

Question 35

Steady budget

Answer 35

ablation equals accumulation | -no change in size

Question 36

the velocity of glaciers tend to be slower or faster near valley walls and why?

Answer 36

they tend to be slower near the valley walls due to friction

Question 37

If the accumulation area for a glacier is 10 km2 and the ablation area is 5 km2, the status of the glacier budget is ……

Answer 37

Cannot be determined because we don't know how much has snowed and the elevation

Question 38

Which of the following is NOT characteristic of Ice Ages?

Answer 38

More CO2

Question 39

climate fluctuations within ice ages are primarily controlled by :

Answer 39

variations in earths position and orientation relative to the sun

Question 40

Why are glaciers observed at lower elevation near the equator that at latitudes of 30 degrees North and South of the equator?

Answer 40

Rate of snowfall is higher near the equator