Glacial Depositional Landforms

Question 1

Lateral moraine:

Answer 1

• Debris from freeze thaw weathering of the valley sides falls onto a glacier
• It is then transported and deposited at the edge of the glacier where it melts

Question 2

Medial moraine:

Answer 2

• At the confluence of two tributary glaciers, the lateral moraine joins to form a medial moraines
• This is then deposited during ice melt and retreat

Question 3

Terminal moraine:

Answer 3

-Debris is deposited at the maximum extent of a glacier, especially if the glacier is in equilibrium and the snout is stationary and debris will be continuously supplied to the same place

Question 4

Drumlins:

Answer 4

• Formed when the ice becomes overloaded with sediment
• When the competence of the glacier is reduced, material is deposited
• The glacier may have experienced a reduction in its competence for several reasons, including melting of the ice and changes in velocity.
• E.g. when glacier ice becomes overloaded with debris when exiting an upland area
• The deposits are then streamlined and shaped by the moving ice
• Forms steep stoss side and elongated lee side

Question 5

Erratics:

Answer 5

• Large pieces of till, usually boulders which are carried by a glacier to a different geographic location to when they originated from
• E.g. huge erratic boulders weighing up to 16,000tonnes were carried 300km from Canadian Rockies to plains of Alberta by Cordilleran Ice Sheet

Question 6

Till Plains:

Answer 6

• Formed when a large section of ice detaches from the main body of the glacier and melts
• The suspended debris will be suddenly deposited and form a large plain of unsorted till

Question 7

Lodgement till:

Answer 7

• Occurs beneath the ice mass when subglacial debris that was being transported becomes lodged or stuck on the glacier bed
• Friction between the subglacial debris and the bed becomes greater than the drag of the ice moving over it

Question 8

Ablation till:

Answer 8

• Material that has been dumped as the glacier melts and thaws
• Can include material that has travelled within the glacier at any point i.e. subglacially, englacially, supraglacially

Question 9

Recessional moraine:

Answer 9

• Moraine deposited during temporary readvancement of a glacier when it begins to retreat again
• Indicates which direction the glacier is retreating
• Lies parallel to terminal moraine