VALLEY OF THE MISSISSIPPI. 21 



generally marks the termination of this stratum 

 throughout its course, which terminates westwardly 

 near to the proper commencement of lake Ontario. 

 Jn several parts of this ridge and its vicinity gypsum 

 lias hcen found, as at the falls of the Gcunessee, at 

 the outlet of Owasco lake, and also contiguous to the 

 falls of Niagara. The Table- Rock, from whence visi- 

 tors commonly view the stupendous cataract, is in great 

 part a mass of gypsum ; which, continually moisten- 

 ed by the falling spray and the neighbouring springs, 

 carries down a portion of the dissolved mass, which 

 is afterwards deposited in rounded nodules in the 

 cavities below. In these rocks we also discover small 

 nodules of galena and the blende ore of zinc, which 

 is more or less prevalent throughout this ridge as far 

 as Grand River in Upper Canada. In the dark grey 

 gypsum of Gennessee, employed in agriculture, there 

 exists a considerable admixture of carbonate of lime. 

 About fifteen or twenty miles west from Queenstown 

 this ridge presents considerable beds of calcareous 

 breccia, or dislocated angular fragments, again col- 

 lected and cemented in a base of the same material. 

 Mr. Maclure traced this calcareous stratum, with its 

 concomitant accompaniment of shells and hornstone 

 nodules, as far as the borders of Lake Champlain, 

 where it terminates in the immediate vicinity of the 

 primitive on the west, and an elongated point of the 

 transition on the east. 



The very imperfect knowledge which we yet pos- 

 sess of the western regions of the Mississippi, pre- 



