262 



STEATIGBAPHICAL GEOLOGY 



remarkable both in their lithological and palaeontological characters. 

 They include two beds of limestone, each of which is overlain 

 by a band of chert-beds ; the lower set is known as the " Red 

 Beds," and the upper as the " Crow limestone and chert." The 

 chert in the Red Beds is 42 feet thick, and has yielded a remark- 

 able set of fish teeth, an account of which, with a complete 

 enumeration of the beds at Leyburn in Wensleydale, has been 

 published by Mr. J. W. Davis. 



4. North Lancashire and Westmoreland 



The area occupied by Avonian limestones in this district is 

 shown on the map (Fig. 87), and the beds have been recently 

 studied and classified by Professor Garwood, who finds representa- 

 tives of both the Tournaisian and Visean stages. 8 The fauna, 

 however, contains some special elements, and the relative abundance 

 of species is different from that prevailing near Bristol, so that he 

 found it well to make different zonal divisions, though these can be 

 roughly correlated with the southern zones. The following table is 

 copied from that given by him : 



The lowest beds are shales and conglomerates found in Ravenstone 



