Published online by Cambridge University Press: 01 May 2009
The grits and conglomerates in the Etruria Marls of North Staffordshire include types with a chamosite-rhombohedral carbonate cement containing interesting spherulitic and concentric structures. Manganese appears in this cement and in certain calcareous bands in the argillaceous fades of the Marls. The clastic fragments suggest derivation from Pre-Cambrian and Cambrian rocks. The heavy mineral suite resembles that listed by Fleet for similar horizons in the Midlands, but staurolite is recorded also.
There is no new evidence bearing on Robertson’s hypothesis that basic igneous rocks of Carboniferous age have contributed to the formation of the Etruria Marls.