■Winchell.] ' O [March 5, 



varies very materially in the percentage of bituminons and carbonaceous 

 matters at different localities ; and the thickness of the dark bituminous 

 beds is also extremely variable. In Michigan and Tennessee the bitumi- 

 nous beds are comparatively thin, but in the former State there is a vast 

 mass of non-bituminous or slightly bituminous shales immediately over- 

 lying the lower portions, which pass by insensible gradations into the 

 typical black shale. These, according to Hunt, occur also in Ontai'io. 

 Proceeding from structural data alone, I united this entire series of shales 

 in one formation which I styled the Huron group ; and I am even now 

 strongly inclined to associate this shale with the strata above rather than 

 with those below. Should it be thought these facts tend to point out the 

 equivalency of the Black Shale proper with the dark shales existing in the 

 lower part of the Portage group of New York, it may be stated that the 

 existence of Lingula spatulata in great abundance in the Black Shale of 

 Ohio and Kentucky and the presence of Discina Lodensis and Leiorliynclius 

 viuliicosta in the Black Shale of Ontario will effectually narrow the deter- 

 mination to the Genesee Shale of New York. '"3 



In the next place, the Carboniferous Conglomerate marks a superior 

 horizon which cannot ordinai'ily be mistaken. The Parma Conglomerate 

 of Michigan, as I have heretofore indicated, '°i occupies the same strati- 

 graphical position. The conglomerate of Western New York identified 

 by the New York geologists with the Coal Conglomerate of Ohio, presents 

 undoubtedly a lithological affinity. The same is true, however, of the 

 conglomerate represented as terminating the Chemung series, and also of 

 the conglomeratic portions of the Catskill group. I am not informed of 

 the lithological or structural grounds upon which these three similar con- 

 glomerates (each locally varying to similar sandstones) have been ranged 

 in an order of sequence. As they are nowhere seen in immediate super- 

 position, it is at least supposable that they are but local occurrences of 

 one and the same formation. If thus identifiable, the question still re- 

 mains to be determined whether the formation lies in the horizon of the 

 Chemung, in that of the Catskill or that of the Coal Conglomerate. The 

 only evidence at i)resent in our possession bearing upon the determination 

 of this question is paleontological. This evidence, as I have already inti- 

 mated, tends to unite the so-called Chemung and Carboniferous conglome- 

 rates and range them in a zone below the Coal Conglomerate of Ohio. 

 This subject will be resumed in the paleontological part of this paper. 



In the third place, it may be remarked that we are now in possession of 

 the means of determining the parallelism of the western strata between 



103 T desire to remark, in passing, that the Marcellus shale of New York is probably represented 

 In Little Traverse Bay by the highly bituminous and earthy limestone near the base of the Ham- 

 ilton group. The same is seen at Thunder Bay Island, Lake Huron, and in the oil wells of Ennis- 

 killen, Ontario. This shale seems therefore, like the Genesee shale, to constitute only an appendage 

 to another formation. 



'"■i Michigan Geol. Eep., 1861, pp. 114, 138. So far as I know this was the first instance in which a 

 geological designation was bestowed upon this formation. The Canadian geologists in the Report 

 of 1863, apply the name " Bonaventure formation " to a series of arenaceous strata " belonging to 

 the base of the Carboniferous series." (p. 404.) In the Atlas to accompany this Report, published 

 in 186fi, the Bonaventure formation is put down as the equivalent of the Coal Conglomerate of the 

 United States. 



