A chatter mark is one or, more commonly, a series of wedge shaped marks left by chipping of a
bedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...
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 a ...
(
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
/ref>
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
{{glaciology-stub