230 



NEW YORK STATE MUSEUM 



Thus the Croton river entering the Hudson on the east through 

 a valley excavated before the Wisconsin epoch has a relatively 

 broad mouth and is evidently engaged in silting up Croton bay, 

 but previous to this existing stage and subsequent to the deposi- 

 tion of Croton point delta at that stage of the ice retreat there 

 took place extensive alterations in the outline of that deposit 

 through erosion along the present path of discharge of Croton 

 river into Tappan sea. There is also the deep cut which divides 

 Croton point delta into two parts now loosely tied together by 

 beaches and swamps. 



Cedar pond brook at Stony Point presents something of the 

 same evidence. It has cut deeply through the North Haverstraw 

 terrace which it built against the ice margin, as soon as the 

 retreat of the glacier admitted of discharge into the gorge, but 

 in its earlier excavatory work cleared away the bed below the 

 present sea level, forming the back bay behind Grassy point 

 which in the present stage has become partly filled with alluvium 

 and swamp growth. 



Peekskill cove might be cited as an analogous instance of de- 

 pression in progress but there are reasons which have been set 

 forth above for considering this as originally unfilled, the ter- 

 races being marginal to ice in the channel. The continuance of 

 the cove as a small harbor, however, is dependent on the depres- 

 sion, for the streams which enter it are of considerable length and 

 have no appreciable delta. 



Popolopen creek on the south of the site of Fort Montgomery 

 is another cove which seemingly should have been filled at least 

 to the present water level were not the land now lower than it 

 was at some epoch after the retreat of the ice sheet. 



Likewise Fishkill creek enters the Hudson through an opening, 

 now marsh filled, indicating considerable excavation below the 

 present level of the sea before the actual water level was attained 

 by the deposition of alluvium. 



Wappinger creek, below the falls, is a drowned valley without 

 a delta. 



Rondout creek, coming in from the west and loaded with sedi- 

 ment, has evidently in recent times filled up a broader channel 

 which demands considerable excavation below the present sea 

 level at some epoch after the retreat of the ice. 



