9 glacial depositional features

9 glacial depositional features

Glacial depositional features are features resulting from deposition of materials made by valley glacier or ice sheet. The material can be deposited by moving ice or by water form melted ice. 

The following are glacial depositional features

  • Till, this is material deposited directly by the glacier. till is always unsorted since glacier is not capable of doing so.
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  • Stratified drift, this are sediments laid down by by glacial melt water. The main difference between  till and stratified drift is that ice cannot sort the sediments it carries hence till is composed of unsorted particle sizes. Stratified drift is sorted according to the size and weight of fragments

  • Erratics, these are large boulders or rock which has been carried by glaciers and deposited in the area where it does not belong. For example it would mean the large boulder of limestone being deposited in an area where the bedrock is made up of granite.
  • The most widespread features of glacier deposition are moraines. moraines are basically ridges of till, there are four main types of moraines. End moraine and ground moraine are common in both Alpine glaciers and ice sheet.End moraine forms at the terminal of the glacier. As the glacier begin to recede, the layer of till is laid down, forming gently undulating surface of ground moraine. Alpine or valley glacier also forms two other  types of moraines. The sides of the valley glacier accumulate large quantity of debris from the valley walls.When the glacier melts these materials are left behind as ridges called lateral moraines. When two advancing valley glacier come together to form a single flow, the till that once was carried along their edges is now joined to form medial moraine

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  • Eskers, these are deposits made by streams flowing in the tunnels underneath the ice, near the terminal of the glacier.
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  • Drumlins are streamlined asymmetrical hills composed of till. The steep side faces the direction from which the glacier advances, while sides points in the direction the ice moved.It is thought drumlins is formed when glaciers advance over previously deposited materials.
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  • Outwash plain, it is gently sloping area ( sometimes fan shaped) comprising sands and gravels deposited by melt water streams flowing from stationary margins of glacier or ice sheet.

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  • Kames, it is small hill or poorly sorted sand and gravel that accumulates in the crevasses or in ice caused indentations in the surface.
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  • Roche mountonnee, this is an asymmetrical hill of exposed bedrock; displaying gently sloping upstream side that has been smoothed and polished by glacier and abrupt steep downstream side