NIAGARA FOSSILS EAST OF THE HUDSON. 355 



Professor Davis : At Rondout there is a very striking outcrop of the 

 Hudson formation dipping at a steep angle to the east, with the Coralline 

 limestone upon it dipping at a tolerably steep angle to the west, and fitting 

 into deep inequalities of the beveled surface of the under formation. The 

 contact could not have been made by a fault ; it was a distinct unconformity. 

 Intermediate between Rondout and Catskill I have found a valley where 

 the structure of the two rocks is clearly discordant — so much so that one 

 could hardly ascribe the discordance to the uneven folding of rocks of dif- 

 ferent resistance. On goiug up the Hudson valley beyond Catskill to the 

 Schoharie region, the Hudson and Helderberg rocks seem to be conformable, 

 both being essentially horizontal ; but the outcrops near their contact are not 

 very extended ; an unconformity by erosion might escape detection there. 



Mr. Walcott : In this connection I wish to place ou record a recent dis- 

 discovery of Niagara fossils* in the tilted and upturned strata east of the 

 Hudson, in the township of Cambridge, Washington county, New York. The 

 section at this point consists of a mass of dark shales with interbedded chert, 

 and small lenticular masses of limestone in which the fossils occur. The 

 stratigraphic relations of this mass of rock to the strata of the Hudson terrane 

 to the west were not ascertained. This discovery is of interest, as it proves 

 that in this area of disturbance, unconformity, and usually of apparent non- 

 deposition of the rocks of the Niagara age, there was one tract in which the 

 Niagara fauna existed, became imbedded, and was not removed by subse- 

 cpient erosion. 



* Orthis Jlabellum, Sowerby ; Ort his, 2 sp. undet. ; Leptaena transversalis. Hall ; StrophomeiM rhom- 

 boidaHs, Wahlen ; Rhynchonella negleeta. Hall: Merisla dubia. Hall ; Ceraurus, of the type of C.in- 

 signis (Beyrieh) Hall, and Ittcenus (fragment of head). 



