what are the different types of glaciers and glacier movement

Question 1

what are the densities of fresh snow, firn and glacier ice

Answer 1

• fresh snow= 0.05g/cm3
• firn= 0.4g/cm3
• glacier= 0.91cm3

Question 2

what is the process of snow turning to glacier ice called

Answer 2

diagnesis= snow to firn to glacier ice

Question 3

how long could it take for diagnesis to happen

Answer 3

30-40 years (valley) and 1000 (ice sheets)

Question 4

what depth will true glacier ice be discovered at and what is it characterised by

Answer 4

100m, blueish colour

Question 5

what defines ice sheet glaciers

Answer 5

expands over 50,000km2, high latitude locations

Question 6

what are the two current ice sheets glaciers and how much of the worlds ice do these possess

Answer 6

antarctica and greenland, 96%

Question 7

what are the typical rates of movement for valley glaciers

Answer 7

20-200m per year

Question 8

what are two locations where valley glaciers are rife

Answer 8

alps and rockeys

Question 9

what is the main difference between cold and warm based glaciers

Answer 9

• cold based glaciers have basal temperature below pressure melting point
• warm based glaciers basal temperature is above PMP

Question 10

what is the pressure melting point

Answer 10

the PMP is the temperature at which the ice is on the verge of melting
-at the surface of a glacier this is 0 degrees, but within the ice mass it will be lowered by increased pressure

Question 11

why is the basal temperatures relationship with PMP so important

Answer 11

glacial movement is catalysed by the presence of meltwater. Where basal temp is below PMP there will be a lack of meltwater.

Question 12

what is an example of a warm based glacier and four characteristics of it

Answer 12

the Athabasca glacier Canada

• moves 2-3 metres per year
• approx 6km long
• basal temp at PMP
• moves mainly by basal slippage

Question 13

give an example of a cold based glacier and four characteristics of it

Answer 13

the merserve glacier antarctica

• average temperature all year is -17 degrees
• PMP is not reached so no meltwater
• limited precipitation, less than 250mm
• moves mainly by intergranular flow or laminar flow

Question 14

what are the two key types of glacier movement and which type of glaciers do these apply to

Answer 14

• basal sliding, warm based

- internal deformation, cold based

Question 15

explain the three types of basal sliding are there

Answer 15

• slippage, ice slides over the valley surface due to meltwater
• creep, ice deforms under pressure do to obstructions on the valley surface
• bed deformation, ice is carried by the downslope movement of sediment on a gentle gradient

Question 16

explain the two elements of internal deformation

Answer 16

• intergranular flow, individual ice crystals move and re-orientate in relation to eachother
• laminar flow, movement of individual layers within a glacier, often layers of annual accumulation

Question 17

describe gradient in relation to internal deformation

Answer 17

• both intergranular and laminar flow can only occur when a glacier is on a slop
• when ice moves over a steep slope it is unable to deform quick enough so fractures form, this is extended flow