the world > the earth > structure of the earth > constituent materials > clay > [adjective] > other clays
cimolian1813
puggy1907
Bradfordian1910
1910 Encycl. Brit. IV. 372/1Bradford clay, a thin, rather inconstant bed of clay or marl situated in England at the base of the Forest Marble, the two together constituting the Bradfordian group in the Bathonian series of Jurassic rocks.