Portage Stages of New Yor~k. 215 



Oneonta. The shales and sandstones which contain these 

 fossils are exposed at the base of the high hill near Oneonta, 

 and are below the reds and grays which compose the terrane to 

 which Vanuxem gave the name Oneonta sandstone. The 

 quarry, a short distance west of Oneonta and below the high- 

 way, contains these species in association with others, especially 

 Paracyclas lirata (Con.) Hall, Chonetes scitula Hall and 

 Tropidoleptus carinatus (Con.) Hall. Above the highway 

 fossils become rare and gradually disappear, the last species 

 noted being Nuculites citneiformis Con. and Paloeoneilo 

 maxima (Con.) Hall, about half way up the hill. It seems 

 that Conrad's name for this zone was not considered in the 

 final reports of the New York Survey, although Vanuxem 

 referred to the horizon in several places ; for instance in 

 describing the hill near Oneonta, mentioned above, it is stated 

 that the Catskill group or Oneonta sandstones of Yanuxem 

 " occupy the highest part of the face of the hill, the base of 

 which is composed of rocks which 1 [Vanuxem] have sup- 

 posed to belong to the Ithaca group." * 



So far as the writer is aware he first called attention to the 

 twofold use of the term " Oneonta group," and indicated the 

 stratigraphic place of each zone.f The zone is well exposed in 

 the Susquehanna, Unadilla, and Chenango river valleys, 

 especially at Oneonta, Oxford and Norwich. In reference to 

 the correlation of the deposits below the Oneonta sandstone 

 there seem to be many conflicting opinions, owing to the fact 

 of the absence of the Tully limestone and the Genesee shales 

 in central and eastern New York. It is true that their dis- 

 tinctive lithologic characters simplify the matter of separating 

 the Hamilton from the overlying Portage in all that area 

 where they are present. But the writer found that a careful 

 study of the facies of the fauna of each zone, supplemented 

 by actual observation of their stratigraphic position and rela- 

 tion in the field, enabled him to separate the fauna of the 

 typical Hamilton from those of the modified Hamilton faunas 

 of the overlying rocks in regions where there was no trace of 

 the Tully limestone or Genesee shale. 



This method of separating the Hamilton from the Portage 

 above was thoroughly tested during the summers of 1890-91 

 in an examination of the Devonian system along the eastern 

 face of the Catskill mountains from Greene county, New York, 

 to Carbon county in eastern Pennsylvania. It was noted that 

 although the fossils in the upper rocks were mostly species 

 found in the typical Hamilton of central and western New 

 York, still there were slight variations or even varietal modifi- 



*Geol. X. Y., Pt. HI, p. 192. 



f Troc. Am. Assoc. Adv. Sci., vol. xxxvi, 1887, p. 210. 



