Glacial Geology of Western New York. 533 



over large districts. Their direction, that of the ice-flow, has beeu 

 referred to above. It is believed that they are subglacial con- 

 ►structional forms, a modification and localization of the ground- 

 moraine. Every gradation can be found from a slight parallel 

 ridging of the general drift surface (finely shown along the Rome, 

 Watertown, and Ogdensburg Eailroad, between Rochester and 

 Niagara) to the bold isolated mound. Between the typical, strong, 

 well-developed ridges (as in the neighbourhood of Clyde), there 

 may often be found another set of minor ridges, as distinct as the 

 great ridges, but perhaps of only a comparatively few feet in height 

 and breadth. 



Moraines. 



The terminal moraine barely enters the southern edge of the State, 

 at Glean and Salamanca, in a re-entrant angle. This line of drift is 

 mapped in all large treatises and textbooks. The greatest develop- 

 ment of morainal drift in the eastern half of our area fills the heads 

 or southern ends of the valleys of the lake region, making aa 

 irregular and curving belt. This has been well illustrated by 

 Professor Chamberlin.' In the larger north and south valleys of 

 the " Finger" lake region, the moraine is usually an enormous drift 

 mass of characteristic topography which blocks the valley and 

 establishes the water-parting. Upon the high intervening ridges the 

 moraine is inconspicuous or quite wanting. It seems evident that 

 in the lake district the ice-field was, during recession, divided into 

 practically distinct valley glaciers. 



In the western and south-western portion of the area the moraines 

 are more numerous and irregular lines. Two systems exist : one 

 north-east and south-west, parallel with Lake Erie, in the south-west 

 corner of the State ; the other somewhat parallel with the Ontario 

 shore, in the north-west corner of the State. These have been, 

 mapped by Mr. Frank Levex'ett.- 



In the districts of well-developed drumlins morainal drift is almost 

 wanting, but large kame areas suggest pauses of the ice-front. It 

 would appear that the forces producing drumlins and moraines have 

 not both been fully effective in the same locality. They seem in. 

 some degree mutually exclusive. 



Glacio-Aqueous Deposits. 

 Eskers. 

 These linear masses of gravel and sand, deposited in the beds of 

 overloaded subglacial streams, are not common. Those seen lie in 

 the bottom of valleys. A very large one, though not of great length, 

 is situated in the Irondequoit valley, near Pittsford.^ Other well- 

 defined eskers have been seen by the writer between Palmyra and 

 Marion, Wayne Co. ; near Gorham, Ontario Co. ; in Henrietta Town, 



1 "Terminal Moraine of the Second Glacial Epocli" : 3rd Annual Report, 

 U.S. Geol. Surv., pp. 291-492. Plate xxxiii covers the area of Western New York. 

 '^ Amer. Journ. Sci., vol. L, pp. 1-20. 

 ^ bee Journal of Geology, vol. iv, p. 135. 



