292 IDENTITY OF THE WESTERN FORMATIONS 



an abundant fossil in New York, and among the thousands of 

 specimens of rocks and fossils in the State collection — the results 

 of the geological survey — the Calenipora appears but from three 

 positions, and one of these seems to me equivocal. The lowest 

 position is the Clinton group, from which one specimen only 

 appears, two being all that are known to have been found. The 

 second position is the upper part of the Niagara limestone, wliere 

 it is common, and occurs in numerous localities. The third po- 

 sition is from what is considered the water-lime group. But in 

 order that this fact may be fully appreciated, it should be known 

 that wherever the Catenipora appears in the water-lime group, 

 the Onondaga salt group has nearly thinned out, thus bringing the 

 Niagara group very near the water-Ume. At some localities of 

 this kind, the Catenipora is in a mass, which at Schoharie is known 

 as the " Coralline limestone," and which is separated from the 

 water-lime (as characterized by fossils) by twenty-five feet or 

 more of a soft ash-colored rock destitute of fossils. This coralline 

 limestone contains no fossUs in common with the true water-lime 

 above. It rests upon a green shale with iron pyrites, which, from 

 the absence of the Medina sandstone and conglomerate, is suc- 

 ceeded below by the Hudson river group. 



The point to be decided is, whether the green shale, containing 

 iron pyrites, is the representative of the Clinton, or of the Onon- 

 daga salt group. If the former, then the " Coralline limestone " 

 holds the place of the Niagara limestone, and must be considered 

 its equivalent ; but if the latter, then it is a part of the water-lime 

 group. But in all instances which I have known, where the 

 Catenipora occurs in the so called water-lime group, there has 

 been an extreme thinning out of the inferior groups, so that this 

 one and the Hudson river group are brought within a short dis- 

 tance of each other. I might observe, also, that there are several 

 species of fossils in the " Coralline hmcstone" which appear to 

 be identical with some in the Niagara group, and which are not 

 found in the water-lime group where the intermediate rocks are 

 largely developed. 



In the paper before alluded to, the name Niagara limestone 

 was sometimes used as synonymous with Cliif limestone. It 



