REVIEW OF GtEOLOGHCAL STRUCTURE. 23 



of north-eastern Pennsylvania and Ohio. That the Vespertine connects 

 through this gap with the Waverly of Ohio is indicated by the Waverly 

 fossils found continuously from McKean county to the Ohio line, but that 

 the Umbral and Catskill do not reach Ohio seems demonstrable. 



The local red color of the Bedford shale is certainly insufficient proof 

 of relationship with the Catskill, while the palaeontological evidence is 

 incompatible with the theory of their identity. The Bedford shale con- 

 tains in some places great numbers of fossils, among which may be 

 mentioned Syringothyris typa, Spiriferina solidirostris, Orihis Michelini, Rhyn- 

 chonella Sagerana, Chonetes Logani, etc., all Lower Carboniferous species, 

 while not a trace of the Catskill fishes has yet been found in Ohio. 



The truth in regard to the Catskill formation probably is that it was 

 formed in an enclosed — perhaps fresh water — basin which had its centre 

 in south-eastern New York and eastern Pennsylvania, and that it shoaled 

 away to a Chemung shore in western Pennsylvania, beyond which its 

 deposits did not extend. 



The Cleveland Shale is considered by Prof Lesley to be of Chemung age, 

 but this was necessitated by his identification of the Bedford shale with 

 the Catskill, and the arguments against one are as cogent against the 

 other. As has been- already stated, the fossils found at and even under 

 the base of the Cleveland shale are identical with those of the Bedford. 



It may be thought that the preceding remarks are inconsistent with 

 the view before presented, that the Chemung and Catskill as well as the 

 Waverly group should be included in the Carboniferous system, for if all 

 are parts of one formation why insist upon their distinctness ? It is 

 true, however, that the well-marked subdivisions of each formation hold 

 invariable positions in regard to each other, and are characterized by 

 differences in lithological characters and fossils, although some species 

 are usually common to all the members of the group. We may hereafter 

 find in Pennsylvania such a blending of Chemung and Waverly fossils 

 as shall unite them more closely than heretofore, but such blending 

 would in no wise affect the question of the identification of the subdi- 

 visions of the Carboniferous system in Pennsylvania with those of Ohio. 



THE LOWEE CARBONIFEROUS LIMESTONE. 



In the discussion of the phenomena presented by the Carboniferous 

 system in Ohio, published in Vol. I, Geology, of this Report, mention is 

 made of the discovery by Prof. Andrews of a thin bed of limestone in 

 the southern part of the State, proved by its fossils to be the representa- 

 tive of the Chester limestone of Illinois, the upper member of the great 

 Carboniferous limestone series. Pacts are also stated there which prove 



