Graywacke sandstone
Lithogenous sedimentary rock.
Graywacke is a fine-to-coarse grained, dark gray to brown “muddy” sandstone or fine-grained conglomerate composed of firmly cemented fragments (as of quartz, feldspar, and rock fragments that commonly volcanic in origin). Graywacke sandstone is typically poorly sorted. Graywacke is the most common sandstone found in the western Coast Ranges of the North America, formed from sediments derived from volcanic arc, like the modern Cascades Range. It is often associated with deep, offshore submarine fan deposits (turbidites).
This sample comes from the Santa Cruz Mountains, Santa Cruz County, California. |
| https://gotbooks.miracosta.edu/rocks/sedimentary/45.html |
2/2/2021 |
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