74 
DESCRIPTION OF THE ROCKS 
one continuing above the river, along Rombalds moor, by Baildon hill, 
Bradford, and Bramley fall : that between them are shales and a coal 
bed of some value, worked opposite Keighley, and continued to Ad- 
dingham ; and below the lower one a great part of the Craven shales. 
The same general view applies to the valley of Lothersdale ; where 
above the limestone are thick shales, covered by gritstones which appear 
separated from the range of Sutton crags, by some moderate thickness 
of shales. The shales lying west of Colne are also to be referred to the 
Yoredale series ; and the thick and varied gritstone series between 
Colne and Boulsworth might be considered to include both the Ingle- 
borough and Brimham grits- 
It follows as a strict consequence that the shales of the deep western 
valleys of Todmorden, Marsden, &c., and the limestone shale of Derby- 
shire, are principally to be referred to the Yoredale series ; and the thick 
millstone grits of the same region, viewed as including the whole of 
the shales, grits, coals, &c. which lie above the Cam limestones in the 
north of Yorkshire. 
The Nidderdale shales diminish southward, and the Ingleborough grit 
is gradually lost as a distinct member of the group ; the Bolland shales 
appear to retain their thickness as far south as Derbyshire. 
Hence appears the propriety of the terms Nidderdale shale and 
Bolland shale, for these are no where fully developed together, but stand 
as reciprocal and successive terms ; the former being unfolded to 
a maximum of thickness and variety, in a large area, where the latter 
is redueed to a very small thickness, or is wholly extinguished. 
Craven Shales . — The map will shew, better than any tedious descrip- 
tion, the area occupied by the Craven shales and black limestone south of 
a line drawn from Kirby Lonsdale through Settle and Malham to Gras- 
sington, and in general it may be said that in all this tract the strata in- 
tervening between the limestone and millstone grit conform closely to 
the argillaceous rocks called by Mr. Farey, in Derbyshire, 4 the lime- 
stone shale.’ Perhaps the best exhibitions of this thick series are seen 
