Depositional landforms

• What is a terminal moraine and how are they formed?

  A ridge of till extending across a glacial trough, they are crescent shape as the slides of the glacier does nto advance as far as the centre. They mark the furthest point the glacier snout reached.
• what is a lateral moraine and how are they formed?

  a ridge of till running along the edge of a glacial valley. The material accumulates on top of the glacier having been weathered from the exposed valley sides. As the glacier melts or retreats, this material sinks through the ice to the ground and is deposited.
• what is a recessional moraine and how is it formed?

  a series of ridges running transversely across glacial troughs and which are broadly parallel to each other and to the terminal moraine. They are found further up the valley than the terminal moraine. They form during a temporary still-stand in retreat.
• What is an erratic and how is it formed?

  Large boulder transported and deposited by a glacier That has different geology to the area in which they have been deposited
• What is a drumlin and how is it formed?

  A mound of glacial debris that has been streamlined into an elongated hill. formation is not fully understood it could be:

  • lodgement of subglacial debris as it melts out of the basal ice layers
  • reshaping of previously deposited material during a subsequent re-advance
  • accumulation of material around a bedrock obstruction - these are known as rock-cored drumlins
  • thinning of ice as it spread out over a lowland area, reducing its ability to carry debris.
• what are till sheets and how are they formed?

  They are formes when a large mass of unstratified drift is deposited at the end of a period of ice sheet advance