PLEISTOCENE MARINE SUBMERGENCE 29 



From the data at hand it appears that New York State was not 

 raised as a rigid body but by a progressive wave movement. The 

 south side of the Iroquois basin suffered about one-half of its total 

 rise during Iroquois time. The northern part of the basin was 

 lifted very little until after extinction of Iroquois. The New York 

 City district did not rise at all until the ice was gone, for not until 

 the ice front had withdrawn considerable distance was there any 

 eft'ective reduction in the weight of the ice cap. The question is, 

 Did the wave uplift of the land ever overtake the receding margin 

 of the iwaning glacier? In a former paper the writer expressed a 

 negative opinion (27, page 250), but with further study and in 

 the light of the accompanying charts it. seems probable that some 

 small rise occurred at Covey hill while the thin ice margin yet 

 lingered against that northern salient. 



DESCRIPTION OF THE SHORE FEATURES 



Long Island 



The amount of Postwisconsin submergence is shown in plate 3, 

 The positive evidences of submergence are abundant and sufficient, 

 the only ones lacking being bars of wave construction and marine 

 fossils. The absence of bars on sand plains has been described 

 in an earlier chapter ; and absence of fossils on a shore of abundant 

 drifting sand is probably to be expected. 



This subject has been recently traversed in a published paper 

 (55)> to which the reader is referred for fuller discussion. For 

 this present writing it will be sufficient td enumerate some of the 

 characters which prove the burial in the open sea. 



1 The island lies entirely within the area of postglacial 

 depression. 



2 Positive proof of the submergence of the near-by valleys of 

 the Hudson and Connecticut. 



3 The evident shore lines about the eastern moraines. 



4 The admitted wave-eroded origin of the cliff' extending from 

 the west end of the island to 6 miles beyond Jamaica. 



5 The very smooth, even surface of the lower parts of the area. 



6 The materials of the plains and the occurrence of surlicial 

 loams over large tracts of the lower plains. 



* 7 The subdued, wave-smoothed surfaces of the moraines beneath 

 the theoretic plane, and the very rough, harsh, unsubdued surface 

 of the same moraines above that plane. 



