"Greywacke is a variety of sandstone characterized by its poorly sorted angular grains of quartz, feldspar, and other small rock fragments. Greywacke is a texturally immature sedimentary rock generally found in Paleozoic strata." Of interest: quartz and feldspar are earth's most plentiful minerals. Paleozoic means Ancient Life when life flourished in the seas. It is the longest of the Phanerozoic eras, lasting from 538.8 to 251.902 million years ago, and is subdivided into six geologic periods (from oldest to youngest): Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.
Of interest: quartz and feldspar are earth's most plentiful minerals. Paleozoic means Ancient Life when life flourished in the seas. It is the longest of the Phanerozoic eras, lasting from 538.8 to 251.902 million years ago, and is subdivided into six geologic periods (from oldest to youngest): Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.