Cold Environments: Fluvioglacial Processes and Landforms

Cold Environments: Fluvioglacial Processes and Landforms

1. The Importance of Meltwater

   • Melting snow helps to enlarge the shallow nivation hollows that eventually become corries when the snow turns to ice
   • Helps to lubricate the base of the glacier.
   • Transports moraine beneath the ice, where it provides tools for glacial erosion
   • When freezes, can help with plucking.
   • Erode channels and form distinctive depositional features - both in front of and beneath the ice.

2. Fluvioglacial Landforms: Meltwater Related Features

   • Meltwater Channels
     • Takes the form of a steep-sided , often dry, valley carved into the landscape
     • Most commonly results from the overspill of a lake that builds up next to or in front of a glacier
   • Eskers
     • Long ridges of sand and gravel. They can be up to 30 meters high and usually take the form of meandering hills-often stretching for several kilometres-that run roughly parallel to the valley sides.
     • Meandering shape suggests they were formed by subglacial river deposition during the final stages of a glacial period
   • Kames
     • Kame Terrace: Most extensive type of kame. Results from the infilling or a marginal glacial lake. When the ice finally melts, the kame terrace is abandoned as a ridge on the valley side.
     • Kame Delta: A smaller feature that forms when a stream deposits material on entering a marginal lake. Small mound-like hills, and can be identified by their deltaic sedimentation characteristics.
     • Crevasse Kame: Some kames arise from the flucial deposition of sediments in surface crevasses. When ice melts, they are deposited on the valley floor to form small hummocks
   • Outwash Plain
     • A gentle sloping area of sands and gravels that forms in front of the glacier.
     • Results from the 'outwash' of sediment carried by meltwater streams and rivers.
     • At the end of a glacial period, huge quantities of sediment will be spread out over the outwash plain by great torrents of meltwater.

Images and files in the map