from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Plural form of graywacke.
Sorry, no etymologies found.
There was the quartz body above, stringers and veins of it reaching through the graywackes and slate, but to handle it
There are also sediments made up of large undecomposed fragments of the original rocks, cemented to form _conglomerates_, or made up of small fragments of the original rocks cemented to form _arkoses_ and _graywackes_.
As John Wells has shown, the influence of Eights’ studies with Amos Easton led him to use Eatonian stratigraphy and therefore to equate fallaciously the Pottsville conglomerates with the conglomerates capping the Catskill graywackes, arguing that coal was not found in the Catskills.
"He had made a discovery at the source of that little tributary, where the erosion of the glacier had opened a rich vein, and on following the stream through graywackes and slate to the first gravelled fissure, he had found the storage plant for his placer gold.