﻿296 Review of the New York Geological Reports. 



Art. IX. — Review of the New York Geological Reports. 



(Continued from Vol. xlvii, p. 380.) 



Grey Sandstone, Shawangunk Grit, and Oneida Conglome- 

 rate. (Formation IV, of Pennsylvania and Virginia.) — By refer- 

 ring to the table on page 355, Vol. xlvii, of this Journal, it 

 will be observed that the Oneida conglomerate forms with the 

 Medina sandstone and Clinton group, a transition series or con- 

 necting link between the lower and middle divisions of the New 

 York system. The eastern geologists are not agreed as to the 

 exact geological position of these strata. Hall, in his tabular 

 arrangement, places the Oneida conglomerate as the highest mem- 

 ber of the Champlain division. Vanuxem considers it a member 

 of the Ontario division subordinate to the Clinton group, as will 

 appear from the following extract from his Report, p. 75 : " The 

 Oneida conglomerate forms a part of the Clinton group, the next 

 mass in the order of superposition. It was separated, as being a 

 convenient point for division, and from the importance which 

 was once attached to this rock, having been confounded with the 

 conglomerate of the coal era, thus giving rise to the wildest cal- 

 culations and distorting the whole of the geology of western New 

 York." Mather, considers the Shawangunk grit a member of 

 the Ontario division, but lying probably below the Medina sand- 

 stone, for speaking of the strata composing the Ontario division, 

 he says : " the rocks of this division may be classed under two 

 groups, 1st. Pyritons strata and red shales and grit (above) ; 

 2d. Shawangunk grit, or conglomerate, (beneath); and 3d. A 

 range of rocks similar to the above, but the identity of which is 

 not completely demonstrated" And again on page 355 of Ma- 

 ther's Report, we find the following paragraph regarding the 

 above strata : " The observations made do not render it certain, 

 whether these rocks are equivalent to the Onondaga salt group 

 or the Medina sandstone, but it is thought probable from some of 

 the mineral characters, no fossils having been seen, that they be- 

 long to the epoch of the Medina sandstone, and that the subja- 

 cent Shawangunk grit is equivalent to the grey sandstone instead 

 of the Oneida conglomerate."* 



As we understand it, ihe identity of the Oneida conglomerate and Shawan 



doubted 



Eds. 



