A chatter mark is one or, more commonly, a series of wedge shaped marks left by chipping of a
bedrock surface by rock fragments carried in the base of a
glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
(
glacial plucking). Marks tend to be crescent-shaped and oriented at right angles to the direction of ice movement.
[Marshak, Stephen, 2009, Essentials of Geology, W. W. Norton & Company, 3rd ed. ]
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 which 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.
Encyclopædia Britannica
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See also
* Glacial polish
*Glacial striation
Glacial striations or striae are scratches or gouges cut into bedrock by glacial abrasion. These scratches and gouges were first recognized as the result of a moving glacier in the late 18th century when Swiss alpinists first associated them w ...
References
Glaciology
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