GEOLOGY AND GEOGRAPHY OF OLAY DEPOSITS 



115 



material, which Dr. Merrill for a while regarded as a portion of 

 Peek's Kill delta ; the size of the pebbles composing it however 

 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, Haverstraw and Cornwall, also at New Wind- 

 sor, the clay is overlain by delta material, 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 fol- 



lowing altitudes : 



East side. 



Croton 100 



Peekskill 120 



Fishkill 205 



West side. 



Haverstraw 100 



West Point 185 



Cornwall 200 



Newburg 205 



Port Ewen 207 



Schenectady 360 



These measurements apply, of course, to the upper terrace, 

 which can be traced along many portions of the river.* 



An examination of the above figures and the distances between 

 the points mentioned indicate an interesting fact. Between New 

 York and Peekskill, a distance of 45 miles, the terrace rises 40 

 feet, or eight ninths of a foot per mile. From Peekskill to West 

 Point the rise is eight feet per mile. From West Point to New- 

 burg the terraces ascend two and one half feet, and from New- 

 burg to Albany about five twelfths of a foot per mile. From the 

 above it would seem that the uplift from New York to Albany 



* For detailed statement of terrace altitudes, see H. Ries, Trans. N. Y. Acad. Scl., Nov., 1891. 



