Glaciation SG1

Question 1

What is the thick ice spread out over land and sea?

Answer 1

Ice Sheet

Question 2

What are the rivers of ice which flow down from high mountains in the river valley?

Answer 2

A Valley Glacier

Question 3

What is the cold phase where global temperatures dropped by approx. 5 degrees causing ice to spread?

Answer 3

Glacial Period

Question 4

What is the warm phase where temperatures increased to present level or above?

Answer 4

Interglacial period

Question 5

What are landscapes shaped by glaciers?

Answer 5

Glaciated landscapes

Question 6

What is a relict landscape?

Answer 6

Places that were glaciated in the past

Question 7

Where are the only two ice sheets in the world?

Answer 7

Antarctica and Greenland

Question 8

What is the name of the last ice age?

Answer 8

Pleistocene

Question 9

When was the most recent Ice Age?

Answer 9

2 million years ago - - 11,700 years ago

Question 10

What % of the earth is currently covered in ice?

Answer 10

10%

Question 11

What % of the earth was covered in ice 18,000 years ago?

Answer 11

30%

Question 12

What % of the worlds ice is contained in ice sheets?

Answer 12

69%

Question 13

What is basal sliding?

Answer 13

sliding of the glacier over bedrock in warm based glaciers where temperature exceeded pressure melting point and lubricates the surface

Question 14

What is meant by regelation creep?

Answer 14

when the glacier moves over an obstacle (such as a large protruding rock) by melting as the ice moves up over the obstacle, providing lubrication enabling the glacier to slide

Question 15

What is substrate deformation?

Answer 15

when meltwater seeps into the bedrock causing it to become statured and mud like which provides a lubricated plain for the glacier to slide over

Question 16

What is extending and compressing flow?

Answer 16

due to different gradients of the valley floor, the glacier moves quickly in steeper sections and the ice things out (in flatter sections the glacier moves slowly and thickens)

Question 17

What is internal deformation?

Answer 17

the overlying weight of the ice causes the ice near the base to be squashed
the ice crystals align and flatten so they move over each other by intergranular slip

Question 18

What is the step by step order of how glacial ice forms? (6 steps)

Answer 18

1) Snow falls as flakes which have an open, feathery appearance and so can trap lots of air
2) Snow becomes compacted by the weight of later snowfalls
3) The increase in pressure on the buried snow also results in pressure melting and a tiny amount of meltwater forms between the snow crystals which then refreezes
4) More meltwater continues to fill the air passages and refreezes into bigger ice crystals
5) Snow that has survived the subsequent summer melting is called firn/nerve
6) Over time, and with depth, a solid mass of glacial ice forms (in Antarctica it can take 1000 years but in Alpine locations it can be as quick as 25-40 years)

Question 19

What are the four points that applies to warm base glaciers?

Answer 19

High altitudes
Meltwater is present at the base
Move mainly by basal sliding and internal deformation
Temperature of ice at or above pressure melting point

Question 20

Are glaciated landscapes open or closed systems?

Answer 20

Open