﻿1 66 NEW YORK STATE MUSEUM 



Old till. As far as the writer is informed, the first one to 

 recognize Prewisconsin till in New York was F. B. Taylor. In the 

 summer of 1905 he directed attention to the very compact, resistant, 

 stony ; blue till in the bottom of the deep valleys southeast of Buf- 

 falo, which he confidently pronounced older than the overlying and 

 prevailing Wisconsin drift. Subsequently the writer noted other 

 occurrences of similar till. In 1907 Frank Carney published an ac- 

 count of what he regarded as old till in the Keuka valley. 1 



No soil zones or forest grounds lying between the supposed old 

 till and the superfical till have yet been found, to prove the fact of 

 an interval of deglaciation, though such finds may be expected. 

 The writer has noted very sharp distinctions between the two tills, 

 with incorporation of the lower into the upper. An important 

 locality is along the new cuttings for the shortened tracks of the 

 Delaware and Hudson Railroad west of Schenectady, between Kelly 

 station and Duanesburg. Here an incoherent, yellow till, capped 

 with gravel, directly overlies a very hard, dark blue till. The con- 

 trast between the two is very striking and the line of separation is 

 very distinct in some sections ; while in places the older blue till 

 has been plowed up and masses have become incorporated in the 

 yellow till. The blue till retains its color and consistency even when 

 exposed for considerable time to the weather, masses which have 

 lain in the field over the winter being only partially disintegrated. 

 The writer was told that the steam shovels were able to cut the 

 blue " hardpan " with much difficulty and very slowly. 



The blue t : ll has a very different composition and derivation 

 from the overlying and oxidized yellow till. It is impossible that 

 an ice sheet, producing from its burden of ground-up shale and 

 limestone the hard blue till, should suddenly cease to deposit this 

 and at once lay down a yellow oxidized till of entirely different 

 origin. We have here good proof of at least two distinct episodes 

 in ice work. 



The writer has not noted in our Thousands Islands area any 

 example of tills comparable to the old, blue tills farther south, 

 though Cushing thinks that he has seen them. But they probably 

 do occur just south of the boundary, in the northern part of the city 

 of Watertown. Here begins a group of drumlins that extends 

 southward. In the mass of the drumlin forming the dome-shaped 

 hill north of the Black river, and in the small drumlin ridge in the 

 northwest corner of the city, where the Dexter electric line crosses 



1 Pre- Wisconsin Drift in the Finger Lake Region of New York. Jour. 

 Geol. 15:571-85. 



