D. F. Lincoln — Glacial Erosion of New York. 113 



we may yet trace the residue of the old side-notches in de- 

 graded forms. The same is suggested in places by curves in 

 the higher landscape. 



As representing several aspects of this discussion, let us 

 consider the case of the valley at Dundee, which lies ten miles 

 north of Watkins. Its banks are composed of Chemung 

 sandstone, thinly coated with drift ; they rise several hundred 

 feet above the little valley at a moderate angle. The stream 

 runs in a tolerably direct course towards the lake for about five 

 miles, with a moderate fall of 4-20 feet per mile. Passing 

 the village of Dundee — where it runs over rock for a mile- — 

 the stream cuts under the viaduct of the Fall Brook railroad, 

 and at once begins a plunge of 500 feet, which it accomplishes 

 in less than two miles by a line of post glacial gorges. If it 

 could descend to the bed of the lake, the remaining 600 feet 

 of fall would be accomplished in one mile. Such a case 

 appears to show (1) the loss, through lateral shearing, of the 

 Dundee valley, beginning at the point where its plunge com- 

 mences. The modern landscape suggests the same. (2) The 

 deepening of the main channel of Seneca, to an extent sufficient 

 to enable us to bring it into correlation with such tributaries 

 as this upland stream. Obviously, this implies a large figure- 

 several hundreds of feet both laterally and horizontally. 



In conclusion, it is worth notice that Dundee valley, and 

 other valleys at corresponding heights across Seneca Lake, on 

 the east side, agree very fairly in elevation with the system of 

 petty valleys antedating Glacial time which empty into the 

 Chemung near Elmira. The trough of Seneca Lake (with 

 that of Cayuga) stands an exception to the harmony, and its 

 excessive depth is from several points of view irreconcilable 

 with the hypothesis of pure river-erosion, with or without 

 crust-bending. 



Bibliography. 



Laurence Johnson, M.D. ; "The Parallel Drift-Hills of 

 Western New York." Annals of New York Acad, of Sci., 

 vol. ii, Jan. 9, 1882. 



T. C. Chamberlin ; " Preliminary Paper in the Terminal 

 Moraine of the Second Glacial Epoch," in 3d Annual Report 

 of the U. S. Geological Survey. 



D. F. Lincoln, M.D. ; " Glaciation in the Finger-Lake Re- 

 gion of New York." This Journal, vol. xliv, October, 1892. 



Professor Albert P. Brigham, of Colgate University, Hamil- 

 ton, N. Y.; "The Finger Lakes of New York."' Bulletin 

 Amer. Geographical Soc, 1893. 

 Am. Jouk. Sci.— Thibd Series, Vol. XLYII, No. 278.— Feb., 1894. 



