212 NEW YOKE STATE MUSEUM 



silicious, and its coloring is due to the weathering of the lower 

 layer. This formation has a thickness of about 15 feet, but some- 

 times, as at Burlington, it reaches a thickness of 100 feet. Iso- 

 lated bowlders are occasionally found in the clays. The clays 

 are usually horizontally stratified, and contortions of the layers 

 are extremely rare. Numerous marine Quaternary fossils have 

 been found in the overlying sands; the (Skeleton of a whale has 

 also been found in them. 



Openings have been made in these deposits for the purpose of 

 obtaining brick clays at Plattsburg and a few other localities. 



LONG ISLAND CLAYS 



Clay beds are exposed along the north shore of the island and 

 at several points along the main line of the Long Island railroad. 



There is still some doubt as to the exact conditions under which 

 the beds of clay and gravel which form the greater portion of 

 Long Island were deposited, but it is probable that the clays 

 represent shallow water marine deposits of Cretaceous and 

 Tertiary age. 



The age of the clays is still largely a matter of speculation, 

 and will probably remain so in many cases unless palaeontologic 

 evidence is forthcoming. Those on Gardiner's Island are quite 

 recent, as shown by the contained fossils, and the clay on Little 

 Neck, near Northport, is Cretaceous. The age of the Glen Cove 

 clay is probably Cretaceous. 



Cretaceous leaves in fragments of ferruginous sandstone have 

 been found along the north shore of Long Island from Great 

 Neck to Montauk Point, but they are usually much worn and 

 scratched and have evidently been transported from some dis- 

 tant source. The clays at Center Island, West Neck, Fresh Pond 

 and Fisher Island are very similar and are very probably of the 

 same age, possibly Tertiary, but we lack palaeontologic or strati- 

 graphic evidence. At West Neck the clay underlies the yellow 

 gravel, and the latter is covered by the drift, so that is Pre- 

 pleistocene. 



a Hollick, Notes on Geology of the North Shore of Long Island, Trans. N. T. Acad. Sci., XIII. 



