GYPSUM DEPOSITS OF NEW YORK IJ 



stome, with some limestone at the top. The conglomerate is the 

 well known Shawangunk grit which was formerly regarded as the 

 equivalent oi the Oneida conglomerate of central New York. The 

 shales (High Falls) are a minor feature of the northern sections 

 O'f the area, though they gain in strength progressively toward 

 the south and on the New Jersey border have a thickness of sev- 

 eral hundreds of feet, so as to predominate over the other members. 

 They are of reddish color, pyritic, and in plaices graduate upward 

 into sandstone. With their exception, the strata of the region pre- 

 sent a coarser phase of sedimentatiOiU than that inherent to the 

 Salina of the type localities. 



The variation in the character and sequence of the strata com- 

 posing the two areas is explainable by their accumulation in 

 separate basins which received land drainage from different parts 

 of the Siluric conitinent. This condition is indicated by the 

 diagram [fig. 2] which shows the relations of the Upper Siluric 

 formations of central New York. The Salina beds of this 

 region were deposited in the interior or Mississippian sea wihioh 

 received the drainage from the continental lands to the north. To 

 the east the sea was shut off from the Atlantic basin by a barrier 

 of Lower Siluric and earlier formations which extended along the 

 Appalachian protaxis and which had been augmented just previous 

 to the opening of Upper Siluric time by the Taconic uplift. Dur- 

 ing the whole of the Salina age there seems to have been no free 

 communication between the two basins, so that the sediments 

 formed on the Atlantic side of the barrier must have come from 

 the adjacent Appalachian highland. The detritus was brought down 

 to the sea probably by short swift streams; whereas in the inte- 

 rioT basin there was a much more gradual slope from the Adiron- 

 dack and Canadian highlands owing to the existence of a wide 

 coastal pla,in that had been in process of construction from the 

 early Paleozoic times, and the slower moving tributary rivers were 

 able to transport only the finer materials to their outlets. 



From these considerations, it is apparent that the geographic 

 features which were conducive to the deposition of salt and gyp- 

 sum in the first region may have been wholly wanting in the other. 

 The available evidences are, however, scarcely sufficient to warrant 

 the assumption that these minerals do not occur in southeastern 

 New York. The Salina of this region has been so recently recog- 

 nized that Httle attention has been given to its exploration and 

 the descriptions are based wholly on surface exposures. It is 



