Ice Sheets

Question 1

Name 7 glacier types.

Answer 1

Ice sheets, Ice caps, plateau ice fields, valley glaciers, ice fields, piedmont lobes, cirque glaciers

Question 2

What are the main groups glaciers can be put into ?

Answer 2

Constrained by topography, or unconstrained by topography.

Question 3

What are the 3 main components of ice sheets?

Answer 3

Ice domes, outlet glaciers, and ice streams

Question 4

What are ice streams?

Answer 4

Corridors of restricted, fast flowing ice in ice sheets - they drain a very large volume of ice.

Question 5

Glaciers require flow from the _____________ zone to the _____________ zone

Answer 5

accumulation zone to the ablation zone

Question 6

What’s the difference between cold and warm ice?

Answer 6

Cold ice is entirely frozen and below the pressure melting point. Warm ice is at the pressure melting point and has liquid water within it.

Question 7

What’s the difference between temperate glaciers, polar glaciers, and polythermal glaciers?

Answer 7

Temperate glaciers are entirely at the pressure melting point (warm ice only).
Polar glaciers are entirely below the pressure melting point (cold ice only).
Polythermal glaciers contain a mix in varying structures.

Question 8

What is glacial abrasion? What are the two types?

Answer 8

Grinding of fine grained material.
- Striation or polishing

Question 9

What is striation?

Answer 9

When a glacier scores the bedrock with rough protrusions.

Question 10

What is glacial polishing?

Answer 10

When overriding rocks and glacial ice remove sharp protrusions from the bedrock.

Question 11

What is the process of glacial quarrying/plucking?

Answer 11

Fracture of large fragments from bedrock by a glacier

Question 12

What are glacial troughs? What are the 5 types?

Answer 12

Troughs formed by glacial erosion ( NOT U-Shaped valleys)
- Alpine, Icelandic, Composite, Intrusive, Inverse

Question 13

What is areal scouring?

Answer 13

Tracts of subglacially eroded bedrock, aka extended areas with evidence of glacial erosion like abrasion and quarrying/plucking.

Question 14

What is selective linear erosion? Why does it happen and what can we learn?

Answer 14

Deep eroded troughs separated by unmodified land/plateau.
The eroded troughs occur under fast ice sheet flow, giving evidence of the glacial structure and thermodynamics.

Question 15

What are bedrock megagrooves? What causes them?

Answer 15

Enormous grooves in bedrock, usually over 1000m long and 10s of metres deep.
Cause is debated but could be fast ice flow on hard beds.

Question 16

What are the three main small erosional forms?

Answer 16

P forms, Whalebacks, Roches moutonnees

Question 17

What are P forms?

Answer 17

Small erosional depressions in bedrock.

Question 18

What are Whalebacks?

Answer 18

Bedrock bumps formed by abrasion.

Question 19

What are Roches Moutonnees?

Answer 19

Lumps defined by a steady ‘up ice’ incline and a steep ‘down ice’ side. Caused by Ice sheets

Question 20

Define the two types of glacial debris transport and deposition?

Answer 20

Passive: in or on the glacier, usually angular.
Active: Below the glacier, usually shaped and rounded.

Question 21

What is a subglacial till?

Answer 21

Deposits laid down on the ice-bed interface. Subglacial traction till or glaciotectonites

Question 22

Name three types of subglacial bedforms. How do they relate?

Answer 22

MSGLs, Drumlins, Ribbed Moraines. They exist on a spectrum of formation under different ice speeds, ribbed moraines form under the slowest ice, MSGLs under the quickest.

Question 23

What are drumlins?

Answer 23

Smooth oval shaped hills, parallel to direction of ice flow.

Question 24

What are MSGLs?

Answer 24

Mega-scale glacial lineations, more elongated than drumlins.

Question 25

What are Ribbed Moraines?

Answer 25

Formations perpendicular to ice flow.

Question 26

What is ice sheet stagnation terrain?

Answer 26

When a glacier just stagnates and melts where it is, glacier spots over topographical highs melts slower

Question 27

What are large scale glaciotectonics?

Answer 27

When large amounts of sediment are thrusted by glacial advance.