408 New York State Museum 



(Chad wick '19) above merge eastward into the Wells- 

 burg member in central New York. The Northeast 

 shales ("Portage flags" of I. C. White), renamed from 

 the township in Erie county, Pennsylvania, have in New 

 York a thickness of about 400 feet. In their western 

 expression they are practically barren, but eastward as- 

 sume a fossiliferous character. Next to the Dunkirk 

 black shale the most important horizon marker in this 

 group in the western area is the next member, the Cuba 

 sandstone (Williams '87) with a thickness of ten to 15 

 feet and carrying the Spirifer disjunctus fauna of the 

 Chemung. The name is from Cuba village, Allegany 

 county. This sandstone marks the upper limit of Spirifer 

 (Delthyris) mesacostalis in New York State. It is fol- 

 lowed by the 100 to 180 feet of Volusia shales (Chadwick 

 '19; from Volusia, Chautauqua county), a fossiliferous 

 continuation of the Girard shales of Pennsylvania. Above 

 this occur beds including shales of a distinctly reddish 

 or chocolate color, a continuation of the fossiliferous 

 "Chemung beds" of Erie county, Pennsylvania, called the 

 Chadakoin beds from exposures, at Jamestown, on the 

 Chadakoin river, Chautauqua county. These beds lie 

 above the true Chemung in the "Catskill." Their upper 

 limit is at the base of the Panama conglomerate (lowest 

 Mississippian), and they carry Spirifer disjunctus. 



The Chemung fauna is a modified Ithaca-Hamilton 

 fauna and is characterized by Spirifer disjunctus. The 

 fauna is largely a brachiopod and pelecypod fauna and 

 includes brachiopods as Spirifer disjunctus, Spirifer 

 mesacostalis, Cyrtia alta, Athyris angelica, Atrypa reticu- 

 laris, A. hystrix, Schizophoria striatula, Camarotoechia 



