122 TWENTY-SEVENTH EEPOET ON THE STATE MUSEUM. 



est member of that body had asserted, as the result of his 

 investigations, that the rocks at the base of the Niagara Ter- 

 race, consisting of red, gray and mottled marls and sand- 

 stones, were not the continuation of the salt-bearing beds of 

 Onondaga, and elsewhere to the eastward, but a lower forma- 

 tion ; that the Niagara limestone, so largely developed at 

 Niagara and Lockport, was not a continuation of the limestone 

 of the Helderberg, but a distinct formation, having its great- 

 est development toward the west, and gradually thinning to 

 the eastward ; and that instead of lying above the Salt forma- 

 tion, it lay beneath it ; that the Salt formation, extending 

 westward from Syracuse, passed to the southward of the 

 Niagara Terrace, and formed the broad belt of flat country 

 to the south of the range, which is so marked a feature from 

 the Genesee river south of Rochester to the Niagara river at 

 Tonawanda ; thus separating, by a distance of several miles, 

 the limestone of Niagara and that of Black Rock. 



The conditions which originally led to this misapprehension 

 of the relations of the different formations, are, the flat marshy 

 counfoy from the outlets of Seneca and Cayuga lakes to the 

 northward, which has obscured the outcrops, and beyond this, 

 in Wayne county, the great accumulation of drift, which has 

 deeply covered the rock over a large area. If to these we add, 

 that in the earlier geological explorations the line of the Erie 

 canal was that principally traveled, — that the passage from 

 the red and gray marls of the Onondaga region to the red and 

 mottled marls of the Medina Sandstone at Rochester and 

 westward of the Genesee river was through an alluvial or 

 drift country which concealed the underlying rock forma- 

 tions, — the supposed identification of the two formations is 

 not surprising. 



That such views should prevail before continued and con- 

 nected observations had been carried on, we are prepared to 

 understand ; but after nearly forty years of observation, and 

 after the relations of all these rocks have been fully understood 

 for thirty years or more, I submit that it is not worthy of the 

 credit of the American Association to allow such a paper to 

 pass into its publications without serious consideration. Per- 

 sonally I may be interested in this question more than others, 

 since I have published a volume principally upon the palaeon- 

 tology of the formation or group here proposed to be dis- 



