Report of the Statk (xeologist. 



between the Hamilton and Chemung series or, to express it more precisely, 

 between the Hamilton and Sherburne formations. 



In the region under consideration, the, field work directly preliminary to 

 the preparation of the geologic map of New York was conducted by Mr. N. H. 

 Darton, of the United States Geological Survey. Mr. Darton evidently 

 regarded all of the fossiliferous rocks underlying the Oneonta formation as 

 belonging to the Hamilton, and did not consider what became of the Tully 

 limestone, Genesee slate, Sherburne and Ithaca formations which, at Ithaca, 

 fifty miles west of Norwich in the Chenango valley, have a thickness of nearly 

 850 feet. 



Mr. Darton first published an account of this work in March, 1893, in 

 w hich he stated that " The stratigraphic components of the Oneonta forma- 

 tion are somewhat variable in its smaller subdivisions, but certain members 

 preserve general characteristics throughout. The basal beds are grey flags 

 w hich merge into the Hamilton.' 1 1 The same correlation was shown in his 

 figure 2 B through Oneonta and Franklin, 2 where the Oneonta is represented 

 as resting directly on the Hamilton. Again it is stated that "the Hamilton 

 exposed " at the Lyon brook bridge 3 in the Chenango valley, a locality 

 which has been described in this report as representing the top of the Ithaca 

 formation capped by the basal part of the Oneonta. 



At an earlier date the writer published a paper 4 in which was traced the 

 development of the classification of the Upper Devonian system in central and 

 eastern New York. The error of con-elating the fossiliferous beds below the 

 ( >neonta sandstone in the Chenango and Susquehanna valleys with the upper 

 Hamilton was fully explained, both the stratigraphic and palaeontologic evi- 

 dence being given. 



1 American Journal of Science, Third series, Vol. XT.V., p. '-'Ofi. 



2 Ibid., p. 205. 



11 Loc. cit., p. 207. 



1 The Upper Hamilton and Portage stages of central and eastern New York. American Journal of Science, Third series. Vol. 

 XLVI., Sep. 1893, pp. 212-231. 



