PLEISTOCENE MARINE SUBMERGENCE 1/ 



the ice margin on Maine and New Brunswick opened a strait to 

 the St Lawrence gulf. Then, but not before, salt waters entered 

 the lower St Lawrence valley, and slowly worked up into the Cham- 

 plain valley. 



However, by the time salt water reached the Champlain valley a 

 decided change in the physiography had occurred. During the 

 many thousands of years in the history, sketched above land uplift 

 had been in progress in the areas relieved of the burden of the ice 

 cap, and the earlier shore lines of the Hud son- Champlain had 

 undoubtedly been raised much above the waters. How much eleva- 

 tion had occurred before salt-water life entered the Champlain 

 waters we can not now determine. A lifting of 300 feet at Fort 

 Edward, of the 450 feet total rise, would have entirely broken the 

 connection between the Champlain and the Hudson waters. And 

 long before the connection was broken the long stretch of the 

 narroAV strait with its receipt of land drainage from a large terri- 

 tory from both Vermont and New York would have discouraged 

 marine life from making the southward journey. 



It would appear from the known history and the probable 

 physical conditions that marine fossils should not be found in the 

 Hudson valley or in the higher Champlain deposits. 



ABSENCE OF BEACHES IN THE STATEN ISLAND 



REGION 



No continuous beaches (bars, cliffs and terraces) would be 

 expected in the narrow stretches of the Hudson valley. But the 

 absence of distinct, positive beaches on the New Jersey coast, Staten 

 Island and Long Island has been a cause of perplexity even to those 

 who accept postglacial submergence. The necessity for beaches 

 on a submerged land has been tacitly assumed by most writers. It 

 is believed that this assumption is wrong. 



Merrill realized this difficulty, and was the first writer to sug- 

 gest an explanation (30, pages 105-9). I^^ ^ recent paper the 

 writer quoted liberally from Merrill's argument (55, pages 299, 

 301), but for the present purpose it may be sufficient to quote the 

 conclusion of his analysis of the mechanics of beach erosion: 



. . . for the present purpose which is simply to point out the fact that a 

 land surface in process of subsidence or emergence may be subjected to wave 

 action without being incised with distinct shore lines, and alsO' that wave 

 action may produce an inclined plane as well as a terrace or base level. 



It is therefore evident that submergence would not leave a deeply cut shore 

 line as its record unless the rates of land movement were so adjusted as to 



