Depositional Features

?
  • Created by: Isla S
  • Created on: 10-04-14 12:36

Drumlins

  • Resemble an inverted spoon, with its steep side (stoss) facing the direction from which the ice advances. 
  • Up to 3km in length, 600m in width and 100m in height.
  • Typically appear in swarms - their shape means they are identified as basket of eggs topography.
  • Some have a central core of hard rock, or more resistant sediment, but some have no core at all.
  • Debate over formation.
  • Glacier becomes overloaded by moraine in contrast to the energy it has - so struggles to cope with transporting this amount in the lower course.
  • Thus, moraine is deposited.
  • Elongated shape related to direction of movement of the ice - blunt end facing the oncoming ice.
  • Moraine contained within drumlin tends to reflect this pattern.
  • Obstacles in path of glacier may be responsible, encouraging deposited material to be moulded into elongated shape.
  • Other ideas suggest role of meltwater.
1 of 2

Moraine

Moraine - material produced by glacial erosion - unsorted (huge boulders & fine powder) and angular (processes that form material involve freezing and shattering).

  • Ground moraine - spread all over the ground as a glacier retreats up valley in warmer times.
  • Terminal moraine - rocks deposited in a ridge at the maximum advance of the ice.
  • Lateral moraine - ridges of moraine that come from the valley sides and run parallel to those valley sides. 
  • Medial moraine - a ridge of rocks running down the middle of a valley formed by 2 lateral moraines from 2 glaciers coming together.
  • Recessional moraine - run parallel to terminal moraines and these ridges of material mark the retreat of a glacier. Each recessional moraine marks a point where the ice has been static long enough in the glaciers retreat for material to build up. 
  • Push moraine - mounds of material found where a drop in temperature or increase in precipitation allows glacial re-advance, and the glacier pushes previously deposited moraine forward into a new landform. This can change the orientation of the stones found in the original landform. 
2 of 2

Comments

No comments have yet been made

Similar Geography resources:

See all Geography resources »See all Hot and cold environments resources »