52 NEW YORK STATE MUSEUM 



That they were deposited along the ice margin is clearly established 

 by the presence of kames and large drift boulders along the western 

 edge which prove an ice contact front here. The gradual down- 

 ward slope of the sand plains toward the west is to be accounted 

 for by the gradual lowering of the marginal lake level as the ice 

 retreated. 



The depressions within the sand plains may be explained in either 

 one of two ways. They may have been due to isolation of ice 

 masses from the ice margin (possibly sometimes as icebergs) which 

 were partially or completely buried under the delta sand to be 

 melted later thus causing the development of the depressions, or 

 they may have been due to unequal deposition of the delta materials 

 whereby some places were not brought up to the general level. The 

 depth, steepness of sides and irregular shapes of the depressions 

 cause the writer to favor the first view to account for most of them. 



Kames 



Kames, which are hillocks of crudely stratified materials de- 

 posited at the ice edge, are rather abundantly represented except on 

 the east side over the sand plain area. There is no group oflargc 

 kames such as those of Park and Sperry hills within the Boonville 

 quadrangle, or like those of the Remsen quadrangle described in a 

 forrrier report. Probably the best example of a single kame is the 

 one ^ of a mile southeast-south of Greig. It is remarkable for its 

 steepness and symmetry of form and shows a hight of at least 150 

 feet. Many kames are located along the steep western front of the 

 great sand terrace above described, especially from Lyons Falls 

 northward. Other good examples may be found from south of Port 

 Leyden to north of Lyons Falls along the railroad; south and west 

 of Talcottville ; along the road from Turin to Houseville ; south and 

 east of Martinsburg; and even on the highland southwest of 

 Mohawk hill. Frequently, as in the locality last mentioned, there 

 are long low ridges of stratified materials called eskers associated 

 with the kames. 



No doubt kames were also formed over the region now covered 

 by the sand plains, but as the ice gradually retreated from the 

 valley the kames formed along the ice edge were buried under the 

 deep delta deposits. Only those along the western margin of the 

 great delta deposit were left uncovered. Partially buried kames 

 in the midst of a sand plain are finely exhibited around Forestport 

 on the Remsen quadrangle. The sands are there comparatively 



