404 New York State Museum 



Ithaca beds in the central part of the State. Recent 

 studies (Cooper '30) suggest that the Sherburne sand- 

 stone at its type locality and probably for some distance 

 eastward is actually a clastic phase of the Tully, and that 

 at least part of the Sherburne of the Schoharie valley 

 is in reality of Hamilton age, representing the Moscow 

 and at least a portion of the Ludlowville. The Sherburne 

 flags are bluish, rather fine-grained sandstones alternat- 

 ing with smooth, greenish or olive colored shale. Typical 

 marine fossils are absent from the typical Sherburne 

 sands and shales. The Sherburne sandstone represents a 

 bar formation, this bar acting as a barrier which sepa- 

 rated the western fauna in central New York from the 

 modified Hamilton fauna in the eastern area of the At- 

 lantic. The Oneonta sandstone (Vanuxem '40), with a 

 thickness of 2000 to 3000 feet, represents the uppermost 

 Portage in the east (figure 1). The name is derived from 

 exposures in Oneonta, Otsego county. These are red 

 beds, a nonmarine deposit overlying the Ithaca beds from 

 Chenango eastward, the basal portion probably being 

 equivalent in time to the higher Ithaca beds of the central 

 part of the State. The beds are quite unf ossiferous. 

 They are characterized by the fresh or brackish water 

 clam Archanodon (Amnigenia) catskillensis and a small 

 crustacean has been reported. Plant remains as the club 

 mosses Archaeosigillaria and Protolepidodendron, the 

 tree fern Archaeopteris and the seedfern Eospermatop- 

 teris occur. The highest formation in the great Devonian 

 outlier in Orange county, typically exposed in Skunne- 

 munk mountain, is the Skunnemunk conglomerate (Dar- 

 ton '94) which extends south through Bellvale mountain 

 into New Jersey. It has a thickness of 300 to 2500 feet, 



