-1830] WRITINGS OF JOSEPH HENRY. 11 



mean elevation. The highest part of it comprises the sur- 

 face of the counties of Steuben, Allegany, Cattaraugus and 

 Chautauqua; and a little to the north of these, it begins to 

 decline, and finally descends, by three principal steps, to its 

 terminations on the south shore of Lake Ontario. The great 

 elevation and geographical importance of this table, may be 

 inferred from the fact, that it gives rise to several streams of 

 water, which find the level of the ocean at points almost as 

 distant as the extremities of the continent. The head 

 branches of the Alleganj'-, of the Genesee, and of the Susque- 

 hanna, are all found inosculating with each other in the 

 county of Allegany; while their waters separately mingle 

 with the ocean in the gulf of St. Lawrence, the Chesapeake 

 bay, and the gulf of Mexico. But the following heights, 

 from actual survey, will serve to give a more definite idea 

 of its general elevation. 



Chautauqua lake, the largest* sheet of water on this table, 

 and the most elevated of its size in the United States, is 1291 

 feet above the level of the ocean, and 723 feet higher than 

 Lake Erie, although only eight miles distant: its discharged 

 waters descend to the ocean, along the western declivity of 

 the water shed, through the Ohio and the Mississippi rivers. 

 The lowest pass to the east, over a swell of land near Casa- 

 daga outlet in Chautauqua count}^ is 1720 feet high; and 

 another pass in the same swell is 1972 feet. The lowest 

 notch in the height of land between Elm and Little Valley 

 creeks, in Cattaraugus county, is 1725 feet; and between 

 Little Valley and Big Valley, the lowest pass is 2144 feet 

 above the level of the ocean. Franklin ville has an elevation 

 of 1580 feet, and Angelica 1428 feet, although both are situ- 

 ated in vallies. This height of land extends close to the 

 shore of Lake Erie, as it may be seen by the map, that one 

 of the head branches of the Allegany, a tributary of the 

 Ohio, rises within four or five miles of the lake. The sur- 

 face is not broken, but consists of large swells of land, with 

 broad shallow vallies intervening. The principal indenta- 



*It is 18 miles long, contains 16,000 square acres, and discharges 2295 

 cubic feet of water per minute. — Whippo's Report. 



