1891.] NEW YORK ACADEMY OF SCIENCES. 37 



and he furthGr 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 tertiar}'' species from Richmond, Ya. 



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 are 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 clays at Croton Point concretions are 

 common, sometimes forming mas.ses four by six feet and several 

 inches thick. 



