EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 137 



up to and including the Hamilton (Bellvale) shales is cut off at the north 

 by another downthrust against the crystallines, the east branch of the 

 VVoodbury creek following this fault line. This section was described by 

 Dr Ries in his Geology of Orange County with approximate accuracy 

 save for the details which better exposures have developed. What is here 

 regarded as Oriskany and Schoharie grit was then indicated as " H elder- 

 berg" while we can not feel entirely confident that any true Helderberg is 

 exposed. Beginning at the crystallines east of the shallow valley bounding 

 Pine Hill the succession rises in this order: 



Cambric, (fault), Shawangunk grit, Longwood shales (covered for a 

 thickness of 200' ; probably faulted at the top of the Longwood shales as 

 limonites are here developed and contain fossils which appear to belong to 

 the lower part of the Helderberg ; in this case the Rondout, Cobleskill and 

 Manlius formations are lost by the faulting), Oriskany, Esopus-Schoharie, 

 (Ononclaga ; not exposed), Bellvale flags, Skunnemunk conglomerate. 



All beds on this eastern limb are apparently conformable and the 

 formations of immediate interest have a strike n. 50 e., dip 60 w. In 

 ascending order these beds are : 



Thin-bedded silicious sandstone with a few thin i inch layers of dark 

 shale interbedded ; these carry traces of plant stipes, similar to those known 

 in the Helderberg of New York and the equivalent St Alban beds of 

 Gaspe ; (Port Ewen beds ?) 55' 



Heavy-bedded yellow silicious residual sandstone carrying 

 fossils in large masses ; Oriskany 13' 



Thin-bedded compact dark blue sandstone 14' 



Heavy-bedded sandstone lighter in color, gradually changing 

 upward to coarser grain and becoming pebbly. Fossils abundant 

 in upper layers. These beds represent the Esopus and Schoharie 

 grits 230' 5" 



The higher layers of the grit are better exposed along the railroad 

 200 yards northeast of the cut. 



