1868.] HULL PENDLE HILLS. 321 



known that the Millstone series forms a range of hills with an 

 average breadth of a mile and a half, in which the beds dip at 

 angles varying from 30"^ to 50°, or even more. The Yoredale series 

 occupies a tract of country nearly as broad, with the addition to the 

 thickness derived from a rise in the ground in the direction of the 

 dip. The inclination of the beds is nearly as great as that of the 

 overlying Millstone-grit series. 



The thickness of the Yoredale series has been ascertained with 

 much precision by my colleague Mr. Tiddeman, from very clear and 

 continuous sections in the neighbourhood of Clitheroe. Throughout 

 the whole series of grits and shales, there occurs only 350 feet of 

 limestone and occasional thin earthy calcareous bands. The thickness 

 of the entire series, exclusive of the limestone above referred to, is 

 no less than 4675 feet. If, therefore, we add to this the Millstone- 

 grit, we get the following results : — 



Thickness of Millstone -grit series .... 5500 feet. 

 Thickness of Yoredale series 4675 „ 



Total 10175 „ 



In order to ascertain the entire development of the Carboniferous 

 series in this district, it is necessary to add the thickness of the 

 Lower, Middle, and Upper Coal-measures. Unfortunately for our 

 purpose, a portion of the Middle and the whole of the Upper Coal- 

 measures are absent from the Burnley district, having been denuded 

 off from that area. There is, however, no good reason for sup- 

 posing that these Upper beds were not originally deposited here, 

 as there is no sensible break in the series between the Middle and 

 Upper Coal-measures of Lancashire. I think, therefore, I shall be 

 entirely justified in going a few miles to the southward, where 

 these beds occur, and adding the measure of their thickness to that 

 of the underlying beds at Burnley. Taking the thickness as fully 

 ascertained in the neighbourhood of Manchester*, we obtain the 

 following grand sum for the Carboniferous Eocks in Mid-Lancashire 

 as originally deposited : — 



Thickness of the entire sedimentary beds, as originally dejposited in 

 the Burnley district. Thickness 



in feet. 



{Upper Coal-measures. . (Ardwick, &c.). , 201 3 f 

 Middle „ . . (part at Burnley) 4247 

 Lower „ . . (Bui-nley) 2200 



MiUstone-grit series . = (as above) 5500 



Yoredale series (as above) 4675 



Total 18635 



* " Greology of the Country around Oldham and Suburbs of Manchester," 

 Mem. Geol. Survey ; also Quart. Journ. Geol. Soc. vol. xviii. p. 140. The thick- 

 ness of the Coal-measures there given is 7200 feet ; but this does not include the 

 full series of the Upper Measures under Manchester, as the upper limit is con- 

 cealed beneath the Permian formation. 



t This is not the entire thickness, as higher beds are concealed by the uncon- 



