306 EIGHTEENTH REPORT ON THE STATE CABINET. 



attention was called to some peculiar fossils collected at Gait, in Canada 

 West; and in visiting the locality, I discovered some species identical with 

 those before known, from beds which I had regarded as of the Onondaga- 

 salt group in New- York. As this limestone at Gait [and Guelph] was clearly 

 above the great Niagara limestone of the Falls, and contained an almost 

 entirely different set of fossils, I very naturally inferred that it belonged to 

 the next higher formation, or the Onondaga-salt group; and that the 

 Wayne county locality was a feeble representation of the limestone of Gait.* 

 For these reasons the two were treated as identical, and referred to the 

 age of the Onondaga-salt group ; an opinion at that timje sustained by the 

 members of the Canadian Geological survey. 



At a later period, during the Geological Survey of Iowa, I recognised, 

 at the Leclaire rapids on the Mississippi river, a limestone holding the 

 same relative position, having the same lithological character, and contain- 

 ing some identical and many similar fossils with the limestone of Gait or 

 Guelph in Western Canada ; and I thus announced its apparent relations 

 in the Report on the Geology of Iowa. 



" Should the identity of the limestone of these two distant localities be 

 proved, it will afford sufficient ground for separating these beds from the 

 Onondaga-salt group, and for establishing a distinct group. It seems quite 

 probable that the limestones of this period have their eastern extremity 

 in Central New-York, where, from their small development, as well as from 

 similarity of lithological character, there seemed no sufficient ground for 

 separating them from the non-fossiliferous beds of the Onondaga-salt 

 group.! Since, however, in Canada, these beds attain considerable import- 

 ance, and ( admitting the conclusions above given ) acquire a still greater 

 thickness and more distinctive character on the Mississippi river, it seems 

 necessary to elevate them to the same rank as the other groups of the 

 series." Geology of Iowa, Vol. i, p. 75. 1857. 



Some two or three years later, I explored the geology of the central 

 and eastern portions of Wisconsin and the adjacent parts of Illinois. I 

 here found the limestone of Racine, and a part of Waukesha and some other 

 localities, resembling in all respects that of Leclaire and holding many of 

 the same fossils. It is likewise underlaid by the even-bedded darker- 



*The name Gait being considered objectionable, on account of a similar term al- 

 ready in use, and the same rock occurring also at Guelph, it has been called the 

 •' Guelph formation," in the nomenclature of the Geological Survey of Canada. 



*j- My views regarding the presence of the Onondaga-salt group proper in Wisconsin 

 and Iowa have somewhere been called in question, and I have only to remark in this 

 place that I have seen no reasons on my own part, nor facts adduced on the part of 

 others, to change my opinion in reference to the occurrence of this formation in the 

 localities I have heretofore cited. 

 2 • 



