346 R. S. TARR — LAKE CAYUGA A ROCK BASIN. 



• 

 in my opinion, admits of but one explanation, namely, that they were cut by one 

 and the same great glacier, whose margin was broken into several streams in cross- 

 ing the mountain ridge," * * * 



One of the first descriptions of the region from the standpoint of the 

 modern school of glacial geology is by Chamberlin * who, after describing 

 the region, says : 



" That these troughs were the preglacial channels of streams does not seem to me 

 to admit of reasonable doubt ; but that there was a selection and moulding by glacial 

 corrasion seems equally clear, those channels that lay in the directions that would 

 have been pursued had the ice moved on a uniform floor, being ground out wider, 

 deeper, straighter, and smoother, while those in transverse directions were measur- 

 ably filled and obscured. The whole region shows, in the most beautiful manner, 

 the subduing, softening effects of glacial grinding and deposition, without the 

 obliteration of the bolder features of the preglacial configuration." 



This is almost exactly the view presented in the present paper and by 

 Lincoln and Brigham, as stated below; but Chamberlin's statement is a 

 broad generalization, based upon a survey of the entire field, and is not 

 supported by definite proof that this is the actual interpretation of the 

 history of the region. 



Spencer,t writing in 1890 of the lake region of New York, is unshaken 

 in his old opinion that they are no more than river valleys. He uses 

 the fact that the bottoms of these lakes and of Ontario are below sealevel 

 as evidence of a preglacial elevation and postglacial depression of the 

 land, and Upham, in the same volume,J refers to this point as proof of 

 the same alternation of level. 



Wright also agrees with these authors, and says : § 



" Probably, however, they (the Finger lakes) are not due in any great degree to 

 glacial erosion, but they seem to occupy north-and-south valleys, which had been 

 largely formed by streams running towards the St. Lawrence, when there was, by 

 some means (probably through the Mohawk River), a much deeper outlet than now 

 exists, but which has been filled up and obliterated by glacial debris. The ice 

 movement naturall}^ centered itself more or less in these north-and-south valleys, 

 and hence somewhat enlarged them, but probably did not deepen them. The ice, 

 however, did prevent them from becoming filled with sediment, and on its final 

 retreat gave place to water. ' ' 



An important stage in the history of the development of opinion con- 

 cerning the origin of the Finger lakes is reached by the publication of a 

 paper by Dr D. F. Tincoln in 1892.* Hitherto opinions based upon 

 general considerations have been freely expressed, but nothing definite 



* Third Ann. Rep. U. S. Geol. Survey, 1883, p. 358. 

 t Bull. Geol. Soc. Am., vol. 1, 1890, pp. 65-70. 

 X Bull. Geol. Soc. Am., vol. 1, 1890, p. 567. 



gMan and the Glacial Period, 1892, p. 94; also the same conclusion is reached'in Wright's lee 

 Age, p. 323. 



