114 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 17, 



base of the sedimentary series in the north of England, is a mass 

 of strata designated the Shiddaw Slates by Professor Sedgwick, 

 from the circumstance that these slates comprise the Skiddaw range 

 of mountains. They have hitherto been regarded as all but unfos- 

 siliferous, the described organic remains consisting only of two species 

 of Graptolites and four forms which have been attributed by Pro- 

 fessor M'Coy to Fucoids. 



The Skiddaw slates occupy a large area in the northern portion of 

 the Lake-district. They also occur in the south-western extremity 

 of Cumberland, where they form the mountain of Black Comb ; and 

 they are seen in Westmoreland on the eastern margin of the Lake- 

 district, exhibiting themselves in three small patches. The object of 

 this memoir is to point out in detail the circumstances under which 

 they occur in their several areas, and to show that they are more 

 fossiliferous than they have hitherto been regarded, and also to point 

 out their equivalents elsewhere. 



§ 2. The Skiddaw Slates of the West Side of Derwentwater, 

 Bassenihwaite, and Binsey Cray. 



The Skiddaw slates on the west of Derwentwater and Bassenthwaite 

 Lakes, and Binsey Crag, form a portion of the area where they exhibit 

 themselves in their greatest development, both geographically and 

 geologically. The south-eastern boundary of this western part of 

 the Skiddaw slates of Cumberland runs from the lower end of 

 Derwentwater, by the Cat Bells, through Newlands to the head of 

 Crummock- water. From thence it continues westward, and then, 

 passing by the lower end of Ennerdale Lake, turns south-westward 

 round the base of Dent Hill. 



The western margin of this area is marked by the Carboniferous 

 rocks of West Cumberland ; and these rocks, in their eastern ex- 

 tension from Cockermouth, run along the northern edges of Binsey 

 Crag and Caldbeck-fells, forming the northern limit of the older rocks 

 of Cumberland. 



The eastern boundary of the district under consideration is formed 

 by the lower portion of Derwentwater, the River Derwent, Bassen- 

 thwaite Lake, and the ridges extending to Binsey Crag. 



Commencing at Newlands, on the southern border of the Skiddaw 

 slate area, we have, in the hills which lie south of Newlands, the 

 greenish-grey rocks, containing lead-veins, which appertain to the 

 series immediately overlying the Skiddaw slates. On crossing the 

 Newlands valley northwards, the Skiddaw slates make their appear- 

 ance at the southern base of the ridge of hills which contains Aiken 

 Knot and Keskadale Knot. The strata here dip S.S.E., passing under 

 the greenish-grey rocks, and consist of hard, slaty, grey shales, with 

 interstratified coarser beds not exhibiting the same amount of cleavage 

 as the finer deposits. On the north side of Keskadale Knot there are 

 considerable masses of debris which have fallen from the outcrop of 

 the Skiddaw slates. This debris is locally called " Screes," and among 

 it fragments containing fossils are found. These " Screes " occur also 

 on the south side of Keskadale Knot, and yield the same fossils as those 



