GEOLOGY AND GEOGKAPHY OF CLAY DEPOSITS 133 



West Neck, Fresh Pond and on Fisher's and Gardiner's islands. 

 It is important, however, not to confound tilting of the layers, 

 due to slipping, as is the case on Little JSTeck near Northport, 

 with that produced by the ice-thrust. 



Both Dana and Merrill consider Long Island Sound to be 

 of preglacial origin ; the former calls attention to a channel in 

 the southern part of the sound, which probably was that of a 

 river draining Connecticut in preglacial times, and which emptied 

 into Peconic bay. The latter points to the absence of till along 

 the north shore of Long Island where the sound is wide, as evi- 

 dence of the fact that most of the drift was dropped into the 

 sound by the ice in its passage across it. 



On the other hand Hollick* considers that Long Island Sound 

 was dry land until the glacial period, and that the continental 

 glacier upon its arrival on the Connecticut shore plowed up the 

 material from the space now occupied by the sound and pushed it 

 ahead to form the range of hills along the northern part of Long 

 Island. It seems to the writer however that the facts do not 

 support this theory. If we suppose the northern range of hills to 

 be composed of material pushed up out of the area now occupied 

 by the sound, it should everywhere show signs of disturbance. 

 This it does not do. The high hills of sand and gravel at Port 

 Washington for example show no signs of disturbance. 



Mention should be made of a yellow gravel formation. This 

 is found almost everywhere on Long Island, and sections in the 

 railway cuttings frequently show a thickness of 30 or 40 feet. 



Staten Island clays 



The clays of Staten Island are chiefly Cretaceous, as proven by 

 the fossils found in them. (A. Hollick, Trans. N. Y. Acad. Sci., 

 vol. XL) The chief outcrops are at Kreischerville, Green Ridge 

 and Arrochar. Besides the clay there are several "kaolin" 

 deposits. 



In many instances the clays and overlying yellow gravels have 

 been much disturbed by the passage of the ice over them, and in 

 some cases the sections show overthrown anticlines, as on the 

 fingerboard road at Clifton. 



* Notes on Geology of North Shore of Long Island, Trans. N. Y. Acad. Sci., XIII. 



