PLEISTOCENE GEOLOGY OF NASSAU CO. AND BOROUGH OF QUEENS 659 



The position of the ice front is definitely fixed in this field during 

 the retreat by certain sandy deltas backed by niorainal deposits. 

 Elsewhere in the retreat from the main moraine, the j^osition of 

 the ice front is indefinite. In the hypothesis of glacial lakes lield 

 in by it, it is placed at certain points so as to control the outlet of 

 water bodies or lakes whose level is known. Tliere are in tliis 

 district certain drift ridges which simulate the form and extension 

 of the main moraine, and they appear to have developed in part 

 during the retreat from the outer ridge at East New York. Their 

 trend a,nd position accord as nearly as might be expected with the 

 position of the ice front at the time of the Port Washington and 

 College Point stages. 



In a broad sense most of the western part of the island north 

 of the moraine is morainal. But it has a distinct aggregation in 

 belts rudely parallel to the outer moraine and presumably to the 

 ice front as it retreated. Some of the thicker deposits may be due 

 to the working over of the moraine whose disappearance beneath 

 this later drift at Poslyn has been noted. 



A glance at the contours on the map will show a line of irregu- 

 lar, flattish drift hills with hollows lying about 2 miles north of 

 the main moraine. This line is encountered at East Williamsburg. 

 On the north and west of Corona is a curved line of deposits 

 highly suggestive of an ice margin, and the phenomena are repeated 

 in deposits bending around from East Calvary cemetery near Hun- 

 ters northeastward past Pavenswood into Astoria and thence to 

 the East river near Sanford point. This line is, again, about 2 

 miles farther back than the Corona line, and the two bend south- 

 westward toward New York bay, as the line might be expected to 

 bend if the ice were not completely stagnant along tlie axis of most 

 rapid movement down the Hudson valley. Moreover, the Astoria 

 line is apparently a continuation of the College Point frontal 

 deposits, and they are so represented by the line drawn on the 

 accompanying sketch map (pi. 9). The line of the Port Washing- 

 ton stage is not so definitely known. From Littleneck bay it is 

 represented as following the Corona deposits ; it may have rested 

 ao-ainst the drift hills on either side of the southern end of Fluph- 

 ing bay ; the results are practically the same in either view. 



