348 R. S. TARR — LAKE CAYUGA A ROCK: BASlK. 



Brigham, in a very excellent description of the region, arrives at the 

 same conclusion that Dr Lincoln has reached. He says :* 



' ' To review briefly, we suppose the basins to be a composite resultant of valley 

 erosion, glacial scoop and drift barriers, with perhaps a slight element of orography.' ' 



Observations and Interpretations. 



Evidence of buried Valleys. — Coming from a field where the evidences of 

 extensive glacial erosion are limited, and, indeed, where there is distinct 

 evidence of slight erosion, the author attempted to employ the results of 

 his New England experience in the interpretation of the history of lake 

 Cayuga. Thus, while nearly every day he looked upon distinct evidence 

 that the basin of the lake is rock-walled, he did not see the evidence, but 

 was blinded by the simulation of preglacial, mature valley forms.f 



The evidence upon which the title of this paper is based is of two kinds? 

 that of the buried channels in the cliff side, such as those referred to 

 above as described by Dr Lincoln, and the evidence of some of the larger 

 streams which are tributar}^ to the lake, and which flow in preglacial 

 rock valleys above the present lake surface. 



The cliff above referred to is on the eastern shore of lake Cayuga. The 

 rock surface rises and falls, with gentle slope, into a series of undulations 

 of alternating hills and valleys, the latter in no case extending more than 

 a few feet between the lake surface. They are partly, in some cases com- 

 pletely, filled with drift, and, excepting where revealed in cross-section at 

 the lake shore, are not visible in the topograph}^ They certainly seem 

 to be river-formed valleys, and, taken in connection with the other proof, 

 it seems evident that, as Dr Lincoln suggests, they really are. Aside 

 from the valley in the cliff south of Aurora, described by Dr Lincoln, 

 there are others at various points, one of which shows particularly well 

 on the lake shore about midway between Ithaca and Ludlowville. 



Evidence of Salmon Creek. — About six or seven miles north of Ithaca, 

 upon the east side of the lake, there is a tributary to the lake, known as 

 Salmon creek, upon which is situated the town of Ludlowville. The 

 creek flows in a broad, mature valley, distinctly preglacial in type, which 

 extends nearly southward and joins the lake at an angle of 20° or 30°. 

 As in the case of all the valleys, except the postglacial gorges, the hills 



* Bull. Am. Geograph. Soc, vol. xxv, no. 2. 1893, p. 16. 



■j- While the facts in this article are very nearly of the same kind as those put forward by Dr 

 Lincoln, the author discovered them entirely independently. At the time Dr Lincoln's paper was 

 published I was so strongly convinced that the valleys were river valleys, unmodified by ice, that 

 his paper produced no impression. It was only when the clearness of the evidence impressed 

 itself so forcibly on my mind that I could not but be convinced that I again looked at his paper, 

 and found that he had the same kind of proof. Therefore, although independently worked out, 

 the facts in this article are merely confirmations of his studies and deductions. 



