1891. ] NEW YORK ACADEMY OF SCIENCES. 37 
and he further considers that following the submergence there was 
an elevation amounting to 180 feet at New York and at Albany to 
an amount probably not less than 350 feet and perhaps even 400 
feet, and that during this elevation the estuary deposits were exten- 
sively eroded. There is then supposed to have been a second de- 
pression, which at New York amounted to 100 feet. 
As far as my personal observations go, they practically confirm 
Dr. Merrill’s conclusions. A few facts I may, however, add :— 
Regarding the unstratified material overlying the clays at certain 
points we note the following :— 
1. The materials are coarse sand, pebbles, and cobble-stones, lying 
mixed up together, the only locality where stratification was noticed 
being at Dutchess Junction. 
2. The materials are of the same kind as the rocks in that vicinity. 
3. The stones are rounded and water-worn and show no signs of 
glaciation. This material was possibly washed down into the Hud- 
son Valley from the valleys of its tributaries by the floods which 
took place in the late quaternary and during the emergence of the 
land. 
The ice-scratched boulders found in the clay were probably dropped 
there by icebergs floating down the estuary to the sea. 
While in the field I found no fossils, but a microscopic examination 
of the clays has thus far resulted in the discovery of three objects :— 
1. A diatom resembling a tertiary species from Richmond, Va. 
2. A fragment which may possibly be a diatom or desmid. 
3. Another fragment whose surface has a moniliform pattern. 
This closely resembles the surface-marking of the shell of a Buc- 
cinium described by Sir William Dawson from the Champlain de- 
posits of Canada. (Canad. Nat., New Series, vol. vi.) 
Concretions avé very common in the clays and of varied outline. 
One variety found at Coxsackie has formed around the roots which 
penetrate the clay and resembles in form the rhizomorphs described 
by Dr. Northrop (Trans. N. Y. Acad. Sci., vol. x, No. 1) from the 
Bahamas. They may have originated in a similar manner. 
In the sands overlying the cla ys at Croton Point concretions are 
common, sometimes forming masses four by six feet and several 
inches thick. 
