654 NKW YORK STATE MUSEUM 



upper surface, as iiuliciited by the topo<^rapliic map, is about 80 feet 

 above the present scale vel. The outer, or soutlierii edge of this 

 delta is sharply lobate, each lobe corresponding, as in existing deltas, 

 to the encl of some distributary stream coursing in glacial times over 

 its surface to the body of water in which the deposit was accumu- 

 lating. Taking the summit line of these lobes as indicating the water 

 level of the time, it is evident that the water body rose SO feet above 

 the present sealevel. We shall examine presently into the question 

 whether this water was the sea or a lake held in on the north side of 

 the moraine by the ice sheet which still occupied Long Island sound. 



The front of this sand plain or delta is concave toward Manhasset 

 bay, trending northward from Port AVashington and then westf 

 ward about one mile beyond the villai^e. This form of the front is 

 accordant with the outline of the outer curve of the neck. At a 

 distance varvinu: from half a mile to a mile from the lobes the glacial 

 stmtified sands j)ass into till, and the level surface of the old delta 

 gives place to a hummocky topography, sloping generally toward 

 the oi>en waters of the sound, plainly indicating the deposits which 

 were laid down in the presence of the ice or beneath it while the 

 waters pouring from the ice constructed the delta. We thus have 

 the picture of a small semicircular embayment of the ice front. 

 From an inspection of the ground, it appears that the edge of the 

 ice lapped over on the existing land for a distance of three fourths 

 of a mile to nearly a mile from Barker point, around by Sands Light 

 point, and for a slightly greater breadth on the eastern side, a£ 

 least as far as Mott point. Beyond this locality it is quite impossible 

 to discriminate the deposits of the ice made at this stage from the 

 earlier deposits laid down when the ice front was closely pressed 

 against the moraine on the south. 



The structure of the delta as exposed in tlie summer of 1900 is 

 typically deltiform, with beds of sand steeply inclined toward the 

 frontal lobes, each bed having been deposited in its present inclina- 

 tion on the growing edge of the deltii, as the streams coursing over 

 the embankment, already ])uilt up to water level by this process, 

 came to the outer margin and let their load of sand come to rest 

 by sliding down the frontal slope to the angle of repose for that 

 material in water. {See pi. 7 and 8) 



