Geology of Long Island. 347 



The shell-bed was underlain by quicksand bearing water. 



In the vicinity of Manhasset, on the road to Port Washington, 

 are extensive exposures of stratified sand, more or less inclined 

 from the horizontal. About 200 yards south of the post office, 

 on the west side of the road, is a bank about 40 feet high, com- 

 posed of a white, coarse, laminated sand, streaked with hydrous 

 peroxide of iron, the layers dipping S. E. 13°. A little north- 

 east of the post office, along the road, there are banks of red 

 sand cemented together in places by sesquioxide of iron and re- 

 sembling the Cretaceous red sand bed of New Jersey. 



On the shore of Manhasset Bay, near Port Washington, are 

 high banks of coarse yellow stratified sand and gravel. This de- 

 posit is very irregular in its stratification, as it shows in many 

 places the "flow and plunge" structure described by Dana, and 

 which is evidently produced by swift currents. The depth of 

 this formation cannot be determined, it is probably not less than 

 150 feet, and possibly is much greater. These beds dip about 

 15° W. ; the strike is nearly due north and south. Along the 

 shore of Manhasset Bay, from Port Washington to Barker's 

 Point, are extensive banks of stratified sand and gravel, much 

 stained with iron and dipping westward. At Prospect Point 

 and Mott's Point, the banks are composed of coarse gravel simi- 

 lar to that at Port Washington. 



Between Roslyn and Glen Cove, there are high banks of red and 

 flesh-colored sands, while at Carpenter's clay pits a most interest- 

 ing section is presented (fig. 1). The greatest hight of this sec- 

 tion is 73 feet, the strike of the beds being N. 80° W. and the 

 dip about 37° northerly. The layers here are composed of coarse 

 white gravel and sand, apparently consisting of quartz, but sus- 

 ceptible of being easily crushed in the hand. The pebbles are 

 traversed by innumerable cracks, and appear to have been sub- 

 jected to the action of an alkaline solution. Interstratified with 

 the gravel are layers of fine white clay, from six inches to one foot 

 in thickness, stained pink in some places, and containing occasion- 

 al fragments of a soft hematite or red ochre. Besides these beds, 

 there is a deposit of kaolin farther south, but its stratigraphical 

 relations to the layer exposed could not be determined. This kao- 

 lin is a soft white granular clayey substance, consisting chiefly of 

 hydrous silicate of alumina from the decomposition of feldspar. 



