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

by Sir Charles Lyell

Productus calvus, Sow. Min. Con. Syn. Productus horridus, Bronn's Index, &c., King's Monogr., &c.; Leptæna, Dalman.

Magnesian Limestone.

Fig. 338.

Spirifer undulatus, Sow. Min. Con. Syn. Triogonotreta undulata, King's Monogr.

Magnesian Limestone.

The compact limestone (No. 4.) also contains organic remains, especially corallines, and is intimately connected with the preceding. Beneath it lies the marl-slate (No. 5.), which consists of hard, calcareous shales, marl-slate, and thin-bedded limestones. At East Thickley, in Durham, where it is thirty feet thick, this slate has yielded many fine specimens of fossil fish of the genera Palæoniscus, Pygopterus, Cœlacanthus, and Platysomus, genera which are all found in the coal-measures of the carboniferous epoch, and which therefore, says Mr. King, probably lived at no great distance from the shore. But the Permian species are peculiar, and, for the most part, identical with those found in the marl-slate or copper-slate of Thuringia.

Fig. 339.