1891. ] NEW YORK ACADEMY OF SCIENCES. 39 
I am inclined to think that the disturbance at this locality was pro- 
duced by one or more land-slips. 
At Cornwall the upper terrace is underlain by till, and this we 
find to be the usual succession. In only two instances was the 
upper terrace found to have the clay beneath. 
Going further down the river we come to Haverstraw. Here we 
find three terraces, the upper one underlain by till containing large 
boulders; this drift dips under the clay, as can be seen by a section 
exposed at the south end of the village and to the rear of T. Chrys- 
tie’s yard. 
Some two miles west of Haverstraw along the N. J. & N. Y. R. 
Ri. between Thiells and Mt. Ivy is a very interesting little basin- 
shaped clay deposit of elliptical outline. It is not over 18 feet thick, 
as determined by boring. The clay is underlain by till and over- 
lain by two to three feet of the same material containing small ice- 
scratched boulders. The valley in which this deposit lies contains 
numerous ridges of drift, whose longer axes lie parallel to the 
direction of the valley. A section of one of them is exposed near 
the clay deposit. This latter was probably formed in a small tem- 
porary lake under the ice. j 
At Stony Point the upper surface of the clay is very uneven and 
is covered by two to eight feet of unstratified material consisting of 
coarse sand and cobblestones. A similar deposit is found over- 
lying the clay at Low Point above Fishkill. Also at Dutchess 
_ Junction the clay is covered by the same kind of material, this latter 
locality being the only one where any stratification is observable in 
the mass. The layers dip towards the river. 
The delta deposits of the streams tributary to the Hudson are of 
great interest. They afford us an idea of the former size of these 
streams, and also indicate the amount of submergence which took 
place at the several points. 
These delta deposits are made up of two members: Ist, the thinly 
stratified loamy clays which were deposited a short distance from 
the mouth of the river; and, 2d, the coarse, cross-bedded sands and 
gravels which were deposited at its mouth. 
The following streams between New York and Albany have 
formed delta deposits (as noted by Dr. Merrill, Amer. Journ. Sci., 
June, 1891): Wappinger’s Creek, New Hamburgh; Fishkill Creek ; 
Quassaic Creek, Newburgh; Moodna River, Cornwall; Indian 
Creek, Cold Spring ; Peekskill; Pocantico River, Tarrytown; Saw- 
mill River, Yonkers ; Tibbitt’s Brook, Van Cortlandt ; Minisceongo 
Creek, Haverstraw. 
All of these deltas have been largely eroded by the streams which 
formed them, and little is left of them at the present day. 
Dr. Merrill (Amer. Journ. Sci., June, 1891) considers it highly 
probable that some of these deltas once filled a large portion of the 
valley in the Highlands. At Jones’s Point opposite Peekskill there 
is a deposit of thinly stratified loamy clay which may have formed 
a portion of the secondary cone of Peekskill Delta; also at Rose- 
