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  • Print publication year: 2004
  • Online publication date: March 2011

10 - Shaping the landscape

Summary

The effects of glacial erosion and deposition are abundantly clear in any of the world's most beautiful mountain regions. Although now devoid of glaciers, regions such as the greater part of the Rocky Mountains of the USA or the uplands of the British Isles provide a rich legacy of glacial phenomena. Sharp peaks and steep-sided, flatbottomed valleys are typical manifestations of the erosive capability of glaciers, while deposition from glacier ice has produced a variety of heaps of sand, gravel and mixed sediments. Even more abundant glacial deposits are found in the lowland regions bordering mountain ranges, or on the plains that underlie the outer limits of the last great ice sheets.

Glacial erosional landforms

The effects of erosion can be seen on all scales–from small outcrops of bedrock to the world's highest peaks, and to the vast areas of scoured low rocky country of the Canadian Shield. The distinctive imprint left by glaciers permits us to recognize the effects of glaciation in areas that have not been covered by ice for many thousands or even millions of years.

Small-scale features

On the smallest scale of centimetres to metres, glacial erosion is represented by striated, polished and grooved rock surfaces, features which are the result of debris-laden ice at the base of the glacier sliding over a slab of rock. Associated with them are smaller features such as chattermarks and crescentic gouges which are the result of a repeated juddering of an ice-embedded stone on the rock surface.

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