12 



Report of the State Geologist. 



further west in the more typical Portage region. The same beds are known 

 to occur further east, and at Sherburne, in the Chenango valley, they were 

 early termed by Vanuxem, the " Sherburne sandstones." 



Above these lie beds of sandy shale, often with considerable quantities 

 of argillaceous shale, bearing fossils which, for the most part, are Hamilton 

 species, showing no variation. Gradually, however, forms appear which are 

 not known to occur in the normal Hamilton fauna, among others Spirifer 

 m£S(istri(ill.% which becomes abundant and large at about 300 feet above the 

 base of the fossiliferous beds. In the upper portions of the group the fossils 

 are distributed in thin beds, separated by wide, barren intervals ; these barren 

 sandstones and flags finally predominating to such an extent that fossils are 

 seldom seen. In the Otselic river section, fossils which occur in the typical 

 Portage section are very rarely seen ; the fauna is a Hamilton fauna, modified 

 by the presence of some non-Hamilton species, and by certain characteristic 

 variations of the Hamilton species themselves. 



In the Tioughnioga valley, the presence of some of the more abundant 

 and widespread Portage species is noticeable. The commingling of the two 

 faunas in the Cayuga lake section is well known. Through Schuyler county, 

 in sections made at Havana and northward on the w est side of Seneca lake, 

 the predominating fossils are still the brachiopods of the Ithaca group, but 

 with an increase in the representation of the Portage fauna, which manifests 

 itself in places in Yates county by some of its indicial types. It is not until 

 the western limit of Yates county is reached that the normal Portage fauna, 

 with its peculiar types of life, so distinct from those of the Ithaca group, is 

 fairly pronounced, and this expression of the fauna is intensified further west- 

 ward in Ontario and Livingston counties, where evidences of the Ithaca fauna 

 are met with only at rare intervals. 



The Classification and Distribution of the Hamilton and Chemung Series of 



Central and Eastern New York. 



By Charles S. Prosser. 



These investigations of the rock series from Chenango county eastward 

 wi re undertaken principally for the- purpose of tracing the boundaries of 

 the < Mieonta group of sandstones and shales, of ascertaining their stratigraphic 

 and faunal relations to the deposits above and below, and, also, of elucidating 

 so far as possible, the division line between the Hamilton group and the over- 



