graywacke

American  

[grey-wak, -wak-uh] / ˈgreɪˌwæk, -ˌwæk ə /

Or greywacke

noun

1. Geology. a dark-gray coarse-grained wacke.

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graywacke Scientific  

/ grā′wăk′,-wăk′ə /

1. Any of various dark gray, coarse-grained sandstones that contain abundant feldspar and rock fragments and often have a clay-rich matrix. Graywackes are thought to originate in environments where erosion, transportation, and deposition happen so quickly that minerals and rock fragments do not have sufficient time to break down into finer constituents.

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Etymology

Origin of graywacke

1805–15; partly translation, partly adapted from German Grauwache; see wacke

Example Sentences

Dickinson, W. R. Interpreting detrital modes of graywacke and arkose.

From Textbooks • Jan. 1, 2017

Is it primitive, or is it graywacke like Catskill Mountains?

From Personal Memoirs of a Residence of Thirty Years with the Indian Tribes on the American Frontiers by Schoolcraft, Henry Rowe

I received a specimen of slaty graywacke from Lake Superior.

From Personal Memoirs of a Residence of Thirty Years with the Indian Tribes on the American Frontiers by Schoolcraft, Henry Rowe

In basalt, graywacke, porphyry, sandstone, limestone, &c., are certain elements indispensable to the growth of plants, and the presence of which renders them fertile.

From Familiar Letters on Chemistry by Liebig, Justus, Freiherr von

It led up stairs of graywacke, along the brink of slaty cliffs that dropped sheer, hundreds of feet to the stream below.

From The Rim of the Desert by Anderson, Ada Woodruff