Brown crescent-shaped chatter marks on a formation of gray sandstone.
Chatter marks on sandstone south of Lac Beauchamp, in Gatineau, Quebec, Canada

In glacial geology, a chatter mark is a wedge-shaped mark (usually of a series of such marks) left by chipping of a bedrock surface by rock fragments carried in the base of a glacier (glacial plucking). Marks tend to be crescent-shaped and oriented at right angles to the direction of ice movement.[1][2]

There are three different types of chatter marks. The crescentic gouge is an upstream concave that is made by the removal of a piece of rock. The crescentic fracture is a downstream concave that is also made by the removal of rock. The lunate fracture is also a downstream concave made without the removal of rock.[3]

See also

References

  1. ↑ Marshak, Stephen, 2009, Essentials of Geology, W. W. Norton & Company, 3rd ed. ISBN 978-0393196566
  2. ↑ Dictionary of Geological Terms, Third Edition (1984). American Geological Institute Publications. Robert L. Bates and Julia A. Jackson, Editors
  3. ↑ Encyclopædia Britannica


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