A Manual of Elementary Geology / or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments

by Sir Charles Lyell

Fig. 267.

Columnaria oblonga, Blainv.

As seen on a polished slab of chert from the sand of the Upper Oolite, Tisbury.

Among the characteristic fossils of the Upper Oolite, may be mentioned the Ostrea deltoidea ([fig. 269.]), found in the Kimmeridge clay throughout England and the north of France, and also in Scotland, near Brora. The Gryphæa virgula ([fig. 268.]), also met with in the same clay near Oxford, is so abundant in the Upper Oolite of parts of France as to have caused the deposit to be termed "marnes à gryphées virgules." Near Clermont, in Argonne, a few leagues from St. Menehould, where these indurated marls crop out from beneath the gault, I have seen them, on decomposing, leave the surface of every ploughed field literally strewed over with this fossil oyster.

Upper Oolite: Kimmeridge clay. ¹/₄ nat. size.

Fig. 268. Gryphæa virgula.

Fig. 269. Ostrea deltoidea.