greywacke

Tanımlar (İngilizce)

1. isim A hard dark sandstone with poorly sorted angular grains of quartz, feldspar, and small rock fragments in a compact, clay-fine matrix.

   “Endless bleak, rounded hills composed of shales and ribs of tough ‘greywackes’ make up the Southern Uplands – all of such rocks were originally deposited under marine conditions.”