rock flour

American  

noun

1. glacial meal.

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rock flour British  

noun

1. very finely powdered rock, produced when rocks are ground together (as along the faces of a moving fault or during the motion of glaciers) and are thus chemically unweathered

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Etymology

Origin of rock flour

First recorded in 1880–85

Example Sentences

See Examples For:

rock flour

Many glacial tills, glacially derived diamictites, include very finely-pulverized rock flour along with giant erratic boulders.

From Textbooks ● Jan. 1, 2017

Together, the movement plucks off bedrock and grinds the bedrock producing a polished surface and fine sediment called rock flour as well as other poorly-sorted sediments.

From Textbooks ● Jan. 1, 2017

Near the surface, rocks are involved in repeated brittle faulting produce a material called rock flour, which is rock ground up to the particle size of flour used for food.

From Textbooks ● Jan. 1, 2017

Loess commonly starts as finely ground-up rock flour created by glaciers.

From Textbooks ● Jan. 1, 2017

Glaciers may move the weathered rock products, or they may grind the fresh rocks into a powder called rock flour, and thus form soils having more nearly the chemical composition of the unaltered rocks.

From The Economic Aspect of Geology by Leith, C. K. (Charles Kenneth)