Article · Wikipedia archive · Last revised Jun 14, 2026

Chatter mark

In glacial geology, a chatter mark is a wedge-shaped mark left by chipping of a bedrock surface by rock fragments carried in the base of a glacier. Marks tend to be crescent-shaped and oriented at right angles to the direction of ice movement.

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

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.12

There are three main types of chatter marks. A crescentic gouge is an upstream-facing concave mark created when a piece of rock is removed. A crescentic fracture is a downstream-facing concave mark that also results from rock removal. In contrast, a lunate fracture is likewise downstream-facing but forms without the removal of rock material.3

See also

See also

References

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