Review of the New York Geological Reports. 297 



The probability is, that all these siliceous deposits, viz. the 

 grey sandstone, Shawangunk grit, and Oneida conglomerate, 

 should be grouped as one formation, as has been done in Penn- 

 sylvania. There the sandstones and conglomerates of the Kit- 

 tatinny or Blue Mountain, (a continuation of the Shawangunk 

 Mountain,) are all included in formation IV ; they lie between 

 formation III, the great slate stratum of the Kittatinny valley 

 (Hudson River group of New York) and formation V, the red 

 and variegated sandstones of the valley northwest of the Kitta- 

 tinny Mountain, (Medina sandstone and Clinton group of New 

 York.) 



In New York these rocks are almost destitute of fossils. In 

 Pennsylvania, Rogers found some Fucoides, and a "small and 

 very globose species of Terehratula in it." The Esopus mill- 

 stones of New York were quarried in the Shawangunk grit near 

 the village of Kingston. " The fine-grained grits of this forma- 

 tion would make a beautiful and durable building stone." 



Veins of lead ore traverse the Shawangunk grit. The Ulster 

 lead mine near Redbridge on the Shawangunk Mountain, and 

 the EUenville lead mine at the base of the same mountain, have 

 been worked by the North American Coal and Mining Company. 

 So far these mines have not proved productive, and the ore is 

 difficult to work in consequence of being much intermixed with 

 blende. 



The usual thickness of the Shawangunk grit is from sixty to 

 one hundred feet; its maximum in New York is supposed to be 

 about five hundred feet. This formation increases rapidly in 

 thickness, going southward in Pennsylvania; at the water gap 

 of the Lehigh, according to Rogers, it is increased to at least 

 two thousand feet. 



Medina Sandstone. (Lower part of formation V, of Pennsyl- 

 vania.) — This formation is a red or variegated siliceous mass; for 

 the most part a solid rock, but marly and friable in its western 

 extension. Interstratified with it are grey bands of quartzose 

 sandstone. Marine plants or Fucoides, are almost the only or- 

 ganic remains of the red portions ; whereas the grey sandstone 

 beds afford marine shells. 



The superficial outcrop of these strata is represented on the 

 chart by a light red belt bordering the southern shore of Lake 

 Ontario ; narrow in the east, especially in Wayne County, but 

 expanding westward where it enters Canada. 



