Unit 4a

Question 1

How do glaciers move/transport the entrained (picked up) rock debris?

Answer 1

• flowing ice body (glacial transportation)
• flowing meltwater (fluvial transportation)

Question 2

What are the 4 locations where entrained debris can be picked up?

Answer 2

1. supraglacial debris = transported on the surface of the glacier (fluvial/glacial)
2. englacial debris = transported within the glacier (fluvial/glacial)
3. subglacial debris = transported at the base of the glacier (fluvial/glacial)
4. proglacial debris = transported away from the front of the glacier (fluvial only)

Question 3

What is supra glacial debris? What are the characteristics of the material?

Answer 3

where frost shattered, avalanche and other debris falls onto the glacier from the valley side, material is angular and unsorted

Question 4

What is subglacial debris? What are the characteristics of the material?

Answer 4

Small debris accumulated by basal ice freezing, where large boulders can be entrained by deformational flow. Some debris can be plucked from where regelation takes place around irregular bedrock

Question 5

What is englacial debris and what are the characteristics of the material?

Answer 5

occurs as the ice moves at variable speeds forming crevasses where debris can fall into the cracks or be carried by meltwater and trapped within glacier

Question 6

What are erratics?

Answer 6

these are different rock types to the bedrock that they sit on.

Question 7

What is extentional flow and what does it result in terms of debris?

Answer 7

Ice that flows over an increasingly steep gradient will experience internal stress, results in supraglacial debris falling into crevasses and becoming englacial debris

Question 8

What is compressional flow and what does it result in terms of debris?

Answer 8

Ice that flows over a decreasing gradient will experience external stress, resulting in sub/englacial debris moving towards the surface becoming supraglacial debris

Question 9

What 6 glacial landforms are formed due to glacial ice?

What landscape will these landforms be found on?

Answer 9

Drumlins, Terminal morraine, Recessional morraine, Lateral morraine, Medial morraine and Push morraine

Till Plain

Question 10

What 6 glacial landforms are formed due to meltwater?

What landscape will these landforms be found on?

Answer 10

Eskers, Kames, Kame terraces, Kettle holes, Kettle lakes, Varves

Sandur/Outwash Plain

Question 11

What is glacial till known as in the U.K?

Answer 11

Boulder Clay

Question 12

What is lodgement till and how does it form?

Answer 12

This till is plastered on the underlying surface by the glacier above.
This happens when the friction between the debris and the bedrock is greater than the drag created by the glacier
forms subglacially

Question 13

What are the characteristics of lodgement till?

Answer 13

• unsorted, unstratified
• till is comprised of debris ranging from large boulders to a fine matrix of sand, silt and clay
• till is compacted (due to pressure)
• more rounded

Question 14

What is ablation till and how does it form?

Answer 14

this material can be deposited from sub, en and supra glacial debris due to process of ablation
sometimes meltwater can carry away finer material, leads to more angular debris.

Question 15

What are the characteristics of ablation till?

Answer 15

• unsorted and unstratified
• contains larger material and smaller cobbles, but NO fine material
• till is poorly compacted
• clasts are angular

Question 16

What is deformation till and how does it form?

Answer 16

if glacier advances over an area of previously deposited till, underlying sediment can be folded/faulted
till tends to be well compacted, contains different rock types
the patter of till will reflect the sheer stress involved with its formation

Question 17

What is a moraine?

Answer 17

an accumulation of glacial debris deposited by a glacier or left behind as the glacier retreated

Question 18

How can a moraine be categorised?

Answer 18

subglacial or ice- marginal (formed on the edges)

Question 19

What are till plains?

Answer 19

glacial moraine can cover large areas of land, producing extensive flat area of land
(typically 50m thick, above there may be other depositional landforms)

Question 20

What is a drumlin?

Answer 20

an elongated hill, streamlined in the direction of ice flow, composed of glacial deposits (lodgement till)

Question 21

What is a cluster of drumlins known as?

Answer 21

a basket of eggs

Question 22

What are the conditions needed for drumlins to form?

Answer 22

glacier has to have a high concentration of sediment, high amount of meltwater is also needed

Question 23

What is the process called that forms drumlin?

Answer 23

sub - glacial sediment deformation