Glacial Processes

Question 1

What is a glacier?

Answer 1

A large mass of ice that forms over many years from the accumulation and compaction of snow.
Flows slowly downhill due to gravity, shaping the land and impacting the surrounding environment.

Question 2

What is snow?

Answer 2

The material that hasn’t changed since falling

Question 3

What is the density of snow?

Answer 3

50-200kg m-3

Question 4

What is firn?

Answer 4

Wetted snow that has survived at least one melt season without turning to ice

Question 5

What is the density of firn?

Answer 5

400-830kg m-3

Question 6

What is glacier ice?

Answer 6

The interconnecting passes between grains that are sealed off

Question 7

What is the density of glacial ice?

Answer 7

830-917kg m-3

Question 8

When did the last glacial maximum occur?

Answer 8

20,000years ago before present

Question 9

What is the last glacial maximum?

Answer 9

The most recent period during the earth’s history when ice sheets reached their maximum extent

Question 10

What fraction of the earth’s surface is presently covered by glaciers?

Answer 10

1/10

Question 11

How much of the Global North is covered by ice sheets/glaciers?

Answer 11

1.74m km2 (Greenland)

Question 12

How much of Europe and Central America is covered by ice sheets/glaciers?

Answer 12

500,000km2

Question 13

How much of the global south is covered by ice sheet/glaciers?

Answer 13

13.5m km2 (Antartica)

Question 14

How much bigger was Antartica previously?

Answer 14

1.2 X

Question 15

How much bigger was N.Europe Ice sheets?

Answer 15

1500 X

Question 16

How much bigger was N.America?

Answer 16

1000 X

Question 17

How much bigger was Greenland?

Answer 17

1.3 X

Question 18

Why is it important to study glaciers?

Answer 18

To understand their decay and their role in climate and sea level change from past to future

Question 19

What are the defining characteristics of a glacier?

Answer 19

• Ability to move
• Deform & Slide due to gravity
• Moves ice from high accumulation areas to lower ablation areas

Question 20

What are the factors affected ice to snow?

Answer 20

Temperatures less that 0 mean that densification is due to compression and melting and refreezing - faster process
Temperatures more than 0 means that densification is due to compression from overlying weight of snow/firn
- slower process

Question 21

How does a glacier move?

Answer 21

• Driving stresses pushes the ice down the slope
• Basal drag resists
• Ice then reacts like “hot” solids near melting point
• Deforming occurs due to this stress

Question 22

What do early observations of glaciers show?

Answer 22

That flow wasn’t accepted until C.19th

Question 23

What is iceberg calving?

Answer 23

A major component of ablation for tidewater glaciers

Question 24

What happened in Greenland (Calving)

Answer 24

There was a widespread increase during 1996-2006

Question 25

What did the increasing in calving coincide with?

Answer 25

A period of warming air temperatures

Question 26

What is positive mass balance?

Answer 26

Accumulation > Ablation
Net GAIN mass = Thickening
(winter)

Question 27

What does a bright white surface do?

Answer 27

Reflect large portions of SWR back
HIGH ALBEDO
Hinderance to melt

Question 28

What does a dark dirty surface do?

Answer 28

Absorbs SWR
LOW ALBEDO
melts

Question 29

What are three key processes of glaciers?

Answer 29

Crushing
Abrasion
Quarrying