The Graptolite-Fauna of the Skiddaw Slates

Abstract

The term Skiddaw Slates is the name given to all the sedimentary and contemporaneous volcanic deposits of the Lake District and its neighbourhood, which lie below the Borrowdale Volcanic Series. Mr. Marr has shown (Geol. Mag. 1894, p. 122) that the main outcrop of these beds lies north of the mass of volcanic rocks which constitute the central hills of Cumbria. This outcrop seems to be continued in a south-south-easterly direction across the eastern end of Ulleswater to Shap, though it is partly covered by a deposit of Carboniferous Conglomerate. Another mass of Skiddaw Slate forms the hill of Black Cone in the south of Cumberland, and a small outcrop also occurs near Dalton-in-Furness. The same rocks appear to be extensively developed in the Isle of Man, though the beds there seem to be unfossiliferous. East of the Lake District the Skiddaw Slates are again found in the Cross Fell Inlier, and have been mapped in the small inlier of Teesdale. The beds are always much contorted and faulted, and greatly affected by cleavage; also in certain places they have been extensively altered by the protrusion of igneous rocks through them. The largest collections of fossils have been made in the Keswick district, where the beds have been well worked by local observers. Some of these are well preserved, but the best fossils, as a whole, come from the Cross Fell Inlier. The following are the chief localities from which fossils have been obtained:— At Mr. Mart's request I undertook