REPORT OF THE STATE PALEONTOLOGIST I903 343 



Shawangunk grit and conglomerate 



The lowest member of the Ontaric section in eastern New- 

 York is the Shawangunk grit. This designation was first ap- 

 phed to the formation by Mather,^ the term being derived from 

 the mountain area of that name, "which extends from near High 

 Falls in Ulster county southwest through Orange county and 

 beyond the limits of the State. The Shaw^angunk grit, wherever 

 the contact has been observed, is seen to rest unconformably on 

 the Lower Siluric shales. The Shawangunk grit is generally 

 correlated with the Oneida conglomerate, the latter term often 

 being applied to it. Of these two formations the Shawangunk 

 grit has the greater development, the thickness varying from 

 less than 50 feet in parts of Ulster county and gradually increas- 

 ing in thickness to more than 200 feet within a few miles. The 

 Oneida conglomerate in its type section has a thickness of from 

 15 to 20 feet and in its western extension it gradually grades 

 into a sandstone known as the Oswego sandstone, which in 

 Oswego county has a thickness of more than 100 feet. Both 

 the Oneida conglomerate and the Oswego sandstone are transi- 

 tional into the Medina sandstone above. 



It will thus appear that Avhile w^e may consider the Medina as 

 direct!}^ following and transitional from the Oneida in central 

 New York, the sequence of events following the deposition of 

 the Shawangunk grit in eastern New York has never been satis- 

 factorily established. While for many years the red shales lying 

 above the Shawangunk grit in Ulster county and further south 

 have been generally correlated with the Medina of central New 

 York, no proof has ever been set forth to establish their identity 

 with any degree of certainty. Mather^ in the final report of the 

 first district, the western limit of which was as far west as Her- 

 kimer county, did not definitely correlate these red shales, though 

 he was inclined to refer them to the Medina. He says, " The 

 observations made do not render it certain wdiether these red 

 rocks are equivalent to the Onondaga salt group or the Medina 



iGeol. N. Y. ist Dist. 1843. p. 355. 

 2Geol. N. Y. istDist. 1843. p. 355, 363. 



