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

The most ancient structures of the transition formation p 285 with which we are acquainted are slate and graywacke, which contain some remains of sea weeds from the silurian or cambrian sea.

From COSMOS: A Sketch of the Physical Description of the Universe, Vol. 1 by Humboldt, Alexander von

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

Those streams which originate in, or run through districts of granite, limestone, graywacke, &c., present pebbles of these respective rocks abundantly along their banks, at points below the termination of the fixed strata.

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