178 NEW YORK STATE MUSEUM 



with our present knowledge of the facts, the theory here set 

 forth, ^ which re«>:arcls the Esopiis of any jijiven region as the time 

 equivalent of the Oriskany from the Decewville formation, (in- 

 cluding perhaps as Schuchert suggested, the typical Schoharie 

 as a late eastern phase of the Decewville) down to the phase of 

 Oriskany represented at the region in question, seems the most 

 satisfactory. Thus at Becraft mountain, where about 200 feet 

 of Esopus succeed the Oriskany, which here is lower Oriskany 

 as shown by stratigraphy- and paleontology,^ the Esopus repre- 

 sents all of the later Oriskany to the top of the Decewville. But 

 where, as at Schoharie, the Esopus rests on typical middle Oris- 

 kany, it represents only the upper part of the Esopus of Becraft 

 mountain, as is further shown by the diminished thickness 

 (90 ft). 4 



These facts do not do away with the formational name Esopus, 

 or Schoharie, an}- more than the name Marcellus can be abolished 

 as a formational one, although westward it is represented by the 

 upper Onondaga and lower Hamilton. The same relationship is 

 again seen in the Oneonta sandstone and the Portage shales and 

 in the Catskill sandstones and shales and the Chemung shales. 



"■ Professor Chirke has called my attention to the fact that Freeh (Lethaea 

 Palaeozoica II, p. 208-9) has previously outlined this general concep- 

 tion, Freeh however represents the Lower Oriskany as existing in the 

 western region, where judging from his diagi*am (p. 200), he makes his 

 shore zone throughout Oriskany-Onondaga time, his formations being 

 mostly clastic (sandstones, etc.) in the west, and shading off through the 

 argillaceous Esopus and Schoharie to calcareous deposits in the east. The 

 Schoharie is considered by Freeh to be the shore equivalent of the Onon- 

 daga. Ulrich and Schuchert likewise believe in the general equivalency of 

 the Decewville and Esopus (N. Y. State Mus. Bui. 52, p. 658, tab.). 



'Grabau, A. W. Stratigraphy of Becraft Mountain. 



^Clarke, J. M. Oriskany fauna of Becraft Mountain. 



*If the Camden Oriskany is of an earlier type than tlie Oriskany of 



Becraft mountain, it must represent an early Oriskany invasion while late 



Ilelderbergian (Port Ewen) deposits were still laid down in the northern 



part of the Cumberland sea, since there is no faunal or stratic break 



between the Oriskany and Port Ewan of Becraft mountain, nor between 



the Port Ewan and Becraft formations of the same locality. 



! 



