26 WRITINGS OF JOSEPH HENRY. [1824- 



considered as arms or branches of the principal basin, sepa- 

 rated from each other by a high ridge. From the head of 

 Cayuga lake, the edge of the basin turns suddenly to the 

 north along the lake, and passes in a northeasterly direction 

 through the northern part of Cortland county, a little south 

 of Skaneateles lake, in nearly a straight line to the Little 

 Falls on the Mohawk river. Here it suffers, for the first 

 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 traced along the sources of the Mohawk river, 

 Fish creek and the Salmon river, to the valley of the Black 

 river, which may be considered 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 valleys through which de- 

 scend the Grass, the Racket, and the St. Regis rivers. 



From the foregoing description of the southern boundary 

 of the lower subdivision of the St. Lawrence basin, it evi- 

 dently comprises 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, form- 

 ing 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 nearly 

 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 col- 

 lection of water occupies the lower part of an immense hol- 

 low, the deepest depressions of which are more than two 

 thousand feet below the general level of the surrounding 

 mountain surface. As this hollow is situated with its longer 

 diameter directly across the mountain system, it lays bare to 



*See Bigsby's Sketch. 



