CLAYS OF NEW YOEK 589 



present day but traces of these deposits remain, and tlie streams 

 whicli formed tliem have cut down through them below tide 

 leyeh Dr Merrill thinks it highly probable that these deltas once 

 filled a large portion of the valley in the Highlands. At Roseton, 

 as already mentioned, there is a deposit which may have come 

 from the delta of Wapj)inger creek. Also at Jonespoint oppo- 

 site Peekskill there is a terrace composed of transported material, 

 which Dr Merrill for a while regarded as a portion of Peekskill 

 delta; the size of the pebbles composing it caused him to give up 

 this view. There is however in the upper portion of the terrace, 

 a layer of unassorted material which is slightly separated from the 

 rest; also at the south end of the terrace, a portion of thinly and 

 obscurely stratified loamy clay, which may have formed a portion 

 of the secondary cone of this delta. At Croton, Ilaverstraw and 

 Cornwall, also at ISTew Windsor, the clay is overlain by delta ma- 

 terial, and where this occurs, specially at Croton, the upper limit 

 of the clay is comparatively low, it having probably been eroded 

 to a certain extent by the river entering the estuary at that point, 

 and again it is not likely that very much clay would be deposited 

 around the mouth of the river on account of the current. This 

 may have been the case below Peekskill. 



In general the upper limit of the clay increases northward as 

 does the terrace level. To illustrate this point we have the follow- 

 ing altitudes. 



East side 



Croton 100 



Peekskill 120 



Fishkill 205 



West side 



Haverstraw 100 



Westpoint 185 



Cornwall 200 



Newburgh 205 



Port Ewen 207 



Schenectady 360 



