Vll 



Its eastern limits where it formerly met the waters of the Atlantic 

 Ocean were probably where w^e now find the borders of this plateau 

 to be, namely, at the loo-fathom contour." 



*^ Shortly after the advent of the Ice Age the elevation had reached 

 its maximum. The rivers had pre\ iousiy cut deep valleys through the 

 easily eroded material forming the coastal plain in their course to the 

 sea and when the continental glacier, pushing its way southward and 

 eastward, finally flowed over the edges and escarpments of the hard crys- 

 talline rocks onto the soft and incoherent strata of the coastal plain, it 

 scooped it out to a great depth in places and then, either carrying it 

 forward in mass or else pushing and squeezing it ahead in a great con- 

 torted ridge capped by the boulder till, finally left it as part of the 

 terminal moraine. Wherever these conditions have prevailed we find 

 the phenomena to be the same and Long Island may be considered as 

 one of the grandest object lessons in this connection. ' ' 



Just when the period of elevation ended and that of depression be- 

 gan, in fact, whether it was previous to of subsequent to that of great- 

 est ice accumulation, is yet a matter of controversy between authori- 

 ties, but in either case, on the retreat of the glacier, we may picture 

 to ourselves the terminal moraine forming an elevated ridge extending 

 through Staten Island, Long Island and the islands to the eastward, 

 forming a continuous, more or less elevated land connection to the 

 north and east, with what remained of the coastal plain sloping away 

 from it on one side and a trough filled with the water from the melt- 

 ing glacier on the other. 



'^The present rate of coast subsidence is about two feet per cen- 

 tury ; at this rate six thousand years ago practically the whole of the 

 area included within the present twenty-fathom contour would have 

 been above sea level — only the deepest parts of the trough of the 

 sound being below it. ' * 



' * This area, as may readily be seen, includes the whole of Staten 

 Island, Long Island, Block Island, Martha's Vineyard and Nantucket, 

 besides a respectable portion of the submerged coasts eastward and 

 southward. It is also probable that at least a part of this area to the 

 eastward, which at the present time is lower than the twenty-fathom con- 

 tour, has become disproportionately so in modern times by tidal scour- 

 ing, and that it was actually and relatively higher formerly than now. 



*^ Under these circumstances we should, therefore, have had, during 

 a considerable period of time, a continuous strip of land, except for 

 the river outlets, all the way from New Jersey to Massachusetts, sepa- 

 rated by a body of water scooped out by the glacier, which, in its 



