CONISTON LIMESTONE SERIES. 8 1 



these rocks has earned them the title of " rain-spot " slates (as at 

 White Moss Quarry, near Ambleside).^ 



The Bowder Stone in Borrowdale is a tumbled mass of rock 

 belonging to the Borrowdale Series. 



The occurrence of the Borrowdale Series between Ingleton and 

 Settle has been noticed by Sedgwick, Phillips, and Prof. Hughes.* 

 The Volcanic rocks on this horizon, in the area at the foot of the 

 Cross Fell escarpment, consist of submarine tuffs, interbedded 

 throughout a great thickness of strata with beds of the same 

 lithological character, and containing the same fossils as the 

 Skiddaw Slates. Mr. J. G. Goodchild regards these beds, which 

 he terms the Milburn Rocks, as the submarine representatives of 

 the mainly subaerial volcanic accumulations of the Borrowdale 

 Series proper. 



The "Green Slates" are much used for building at Keswick and other places. 

 They are quarried in Borrowdale (north of the Bowder Stone), at Honister Crag, 

 Goat Crag, Castle Crag, Wallow Crag, and Falcon Crag. In many places the 

 slate is of excellent quality for roofing. Some of the beds contain gritstone or 

 greywacke, provincially called " calliard." Good slates are obtained at Tilber- 

 thwaite, and these are coarse fragmentary rocks. 



As John Phillips remarked, in consequence of the superior hardness of the rocks, 

 the mountains formed of the Borrowdale Series assume bolder forms, present more 

 lofty and rugged peaks, and more inaccessible precipices, than the softer slates of 

 Skiddaw. 



An interesting example of minutely faulted slate belonging to the Borrowdale 

 Series has been figured by Mr. J. J. H. Teall.'^ 



CONISTON LIMESTONE SERIES. 



This series forms the Lower Coniston Group, the Upper Group 

 belonging to the Silurian System. It consists of slaty beds in which 

 limestone is more or less prominently developed ; and it includes, 

 in several places, a variable thickness of volcanic beds. The series 

 may be locally divided as follows : — 



Coniston [ Ashgill Shales. 

 Limestone < Coniston Limestone. 

 Series. ( Dufton Shales. 



The total thickness is variable. While in some localities it may 

 not be more than 500 feet, Mr. J, G. Goodchild informs me that 

 under Roman Fell, north-east of Appleby, the limestones and 

 shales are interstratified with a great thickness of alternating 

 felspathic mudstones, tuffs, and ashy grits, of various degrees of 

 fineness, and with occasional beds of lava, which altogether must 

 attain a thickness of not less than 1500 feet. Certain shales at 

 Style-End Grassing were originally grouped with the Borrow- 



1 J. Phillips, in Black's Guide to the Lake District, 1866, p. 239. 

 ^ See also Nicholson, G. Mag. 1869, p. 213. 

 3 G. Mag. 1884, p. I. 



