290 D. F. Lincoln — Glaciation in the 



Aet. XXXVIII. — Glaciation in the Finger-Lake region of 

 New York ; by D. F. Lincoln, M.D., Geneva, N. Y. 



The Appalachian plateau, at the line between New York 

 and Pennsylvania, is composed of Upper Devonian sandstone 

 and sandy shale, dipping slightly to the south, with summits 

 2000-2500 feet above tide level. The valleys are rather deep 

 (400-800 feet), and resemble in a general way those of central 

 Pennsylvania, but without the N.E.-S.W. parallelism of the 

 latter. The elevations do not take the form of ridges ; they 

 consist of broad, clumsy masses, diminishing in steepness as 

 they ascend, and capped with irregular rolling plains. 



The Susquehanna, with its tributary the Chemung, here 

 forms an important depression, north of which the land rises 

 to the height of 2000 feet, again sinking to form the basin of 

 the Finger Lakes. The lakes therefore occupy a section of 

 the northern slope of the Appalachian plateau, which may be 

 defined as extending 100 miles E.-W., from the Genesee 

 Valley to Cazenovia Lake, and about 70 miles N.-S., from 

 Lake Ontario to the curved line of high land just south of the 

 lakes. 



This line of heights corresponds in position with the 

 " Terminal Moraine of the Second Glacial Epoch " of Cham- 

 berlin,* and is defined as a water-parting by the following 

 high points-^Bristol, 2254 ft. ; Urbana, 1940 ; Orange, 2033 ; 

 Newfield, 2095; Dryden, 1888; Virgil, 2133; Solon, 1977; 

 Fabius, 2015 ; Fenner, 1862. f 



The height of land of which these are the summits is cut 

 through by many deep straight valleys, which on the south 

 communicate with the Chemung-Susquehanna valley, while on 

 the north they converge toward a common imaginary center 

 in Lake Ontario. The northerly discharge is intercepted by 

 streams flowing eastward, which unite to form the Oswego 

 River. Most of these north-south valleys are so blocked with 

 drift as to form lakes. 



The middle of the common basin is axially depressed, in a 

 north-south direction ; the depression is occupied by the two 

 largest lakes, Seneca and Cayuga. 



There is a considerable system of minor, preglacial valleys 

 still traceable in the elevated tracts between the lakes. This 

 system, however, has been so disturbed by glaciation that it no 



* U. S. Geol. Survey, Third Report. 



f Triangulation of N. T. State Survey, 1883, 1887. 



