﻿I56 NEW YORK STATE MUSEUM 



Considering their relation to the ice sheet, the kames are essen- 

 tially morainal in so far as they are peripheral or marginal to the 

 ice sheet. Eskers, specially if of great length, are longitudinal, or 

 parallel to the ice movement, and correspond to drumlins of the 

 ice-laid drift. The esker-kames noted above are not quite typical 

 of either class, and' are therefore all the more instructive. In the 

 field these four or five chains are distinct and clean-cut features. 



It should be borne in mind that all these detrital deposits were 

 formed when the ice front was bathed by several hundred feet of 

 water of Lake Iroquois. The streams which drained the ice sheet 

 may have flowed in tunnels beneath the ice (subglacial), or in 

 trenches on the ice (superglacial), or rarely within the ice (engla- 

 cial). To enter the standing water with sufficient force to carry 

 detritus the subglacial streams must have been under considerable 

 head or hydraulic pressure. 



The various differences in these water deposits must be sought 

 in the variation of the glacial drainage in its complex relation to 

 the inclosing ice and to the receiving waters, and to the amount 

 and kind of rock debris at different depths in the ice and within 

 reach of the streams. 1 



Glacio-aqueous deposits 

 Clay plains. The largest in volume and the most extensive of 

 the deposits due to glacial agency, direct or indirect, are the clay 

 plains which were spread by the Iroquois and Gilbert waters. Ex- 

 cept where in the Black river district the moraine and delta oc- 

 cupy the ground the prevailing drift of practically all the terri- 

 tory south of the parallel of Lafargeville is this clay; and also 

 large areas of the lower ground north of this line. With exception 

 of some till and thinly till-masked rock ridges all the lower ground 

 of the Cape Vincent sheet and the southwest half of the Clayton 

 sheet is clay. East of Clayton and east and west of Lafargeville 

 the plains are clay, blending into till, or eastward at Strough into 

 sand. Excellent views are afforded of these prairielike plains from 

 the railroads to Clayton and Cape Vincent. In the northern dis- 

 trict the clay occupies only the valleys and hollows, where the 



1 The reader who wishes to pursue the study of water-laid .drift will find 

 a philosophic discussion by R. D. Salisbury in Glacial Geology of New 

 Jersey. Final Rep't, 5:113-45. 



Kames of Central New York are briefly described by the present writer. 

 Jour. Geol. 4:190-59. See also Am. Geol. 22:177-80; Am. Ass'n Adv. 

 Sci. Proc. 47:278-81. . 



On eskers, favoring their superglacial position, see an article by W. O 

 Crosby, Am. Geol. 30:1-39. 



