Topographical Sketch of the State of J\ m eu> York, 103 



time in the course that we have described, an interruption, and 

 an outlet appears to have been forcibly broken through into the 

 lower valley of the Mohawk, by some tremendous convulsion of 

 nature. From the Little Falls, the edge of the basin may be trac- 

 ed along the sources of the Mohawk river, Fish creek and the 

 Salmon river, to the valley of the Black river, which may be con- 

 sidered a branch of the St. Lawrence basin, extending back almost 

 to the valley of the Mohawk. From the Black river to St. Regis 

 the remaining part of the basin in this state is the narrow slope 

 of land along the St. Lawrence river, and the several vallies 

 through which descend the Grass, the Racket, and the St. Regta 



From the foregoing description of the southern boundary of the 

 lower subdivision of the St. Lawrence basin, it evidently compris- 

 es the richest and most fertile part of the state, and includes the 

 minor basins of the Genessee country, of the Oneida lake, and the 

 valley of the Mohawk river as far east as the Little Falls. It is 

 also evident from the data before given, that the mean elevation of 

 the high land, forming the boundary just described, must be at 

 least 1600 feet above the level of the ocean. On the north side of 

 the lake in Canada,* the edge of the basin probably rises to near- 

 ly the same height, and as the bottom of Lake Ontario, in the 

 deepest places, sinks 900 feet below its surface, or more than 600 

 feet below the level of the ocean, it follows that this collection o^ 

 water occupies the lower part of an immense hollow, the deepest 

 depressions of which are more than two thousand feet below the 

 general level of the surrounding mountain surface. As this hol- 

 low is situated with its longer diameter directly across the moun- 

 tain system, it lays bare to the view on its southern side the differ- 

 ent strata of rocks which deeply interlays the surface of the coun- 

 try to the south, and presents a geological section in this state, 

 perhaps not less interesting than that at Paris, London or 



The lowest pass from the ocean into the St. Lawrence basin 

 throughout its whole extent, except the bed of the St. Lawrence 

 river, is through the vallies of the Hudson and the Mohawk riv- 

 ers. The highest part of this pass is near the Little Falls, and is 

 elevated only 425 feet above the level of tide water. 



The elevation of the lowest passes to the south, between the 

 waters of Lake Ontario and those of the Susquehanna and the 



* See Bigsby's Sketch. 



