638 NEW YORK STATE MUSEUM 



buiUHng bv the direct action of the ice and througli tlie accumula- 

 tion of gravels by water action. 



The till pluiiHi of the moraine in this area is best shown in a road 

 cut about one mile south of East Norwich. The till is here 

 decidedly gravelly rather than clayey, with cobbles up to 20 inches 

 in diameter, rarely, though occasionally ice scratched. The topog- 

 raphy is cast into small knobs more distinct than the 20 foot con- 

 tour lines of the map can be niade to show. The hill over which 

 the road in question passes has a drunilinoid curve, as if the ice liad 

 overridden it. 



The overriding action of the ice shown in the boulders deposited 

 on water-worn gravels in the moraine and by the ice swept curves of 

 many of the knobs is further attested by the outlying meridional 

 ridges between the inner and outer lines of moraines just north of 

 Westbury pond. Their massiveness and accordance in elevation 

 with the inner ridge are good evidence that they were formed by 

 the same phase of ice action which was concerned in the construc- 

 tion of the main ridge of which they are but spurs. 



The thick till phase of the moraine proper shades off imper- 

 ceptibly into the thin till phase of the upper surface of the gravel 

 plains on the north. This latter drift a])pears to be, over most of 

 the area, ordinary ground moraine like that on the mainland far 

 north of the moraines. Only here and there and particularly on the 

 extreme eastern border of the Oyster Bay quadrangle do consider- 

 able patches of till with morainal topography lie north of the main 

 wall, but none of these have the aspect of a frontal deposit. Thev 

 are, rather, thickened deposits of the ground moraine, and their 

 principal relief is molded on the ridges and valleys of the older 

 drift which they mantle. They have therefore on tlie map been 

 distinguished from the deposits which by their linear arrangement 

 and massiness more cleariy pertain to deposition at or immediately 

 beneath the ice front. 



The stratified gravels in the moraine appear to belong to two dis- 

 tinct categories as regards the mode of their origin : 1) ontwashed 

 gravels laid down at the ice front and subsequently pushed up into 

 ridges ; 2) high cones or fans deposited along the ice front by out- 

 pouring streams either from fountains such as Russell has described 



