566 PROCEEDINGS OF XKW YORK MEETING. 



even approximately proportionate, upon certain parta of it- area, to the thickness 

 the ice accumulation. The sea, after the retreat of the ice, extended over the basin of 

 Lake Cham plain and far up the St. Lawrence and * »t t n w.i valleys, but no Quater. 

 nary marine beds are found about Lake Ontario nor thence westward. In 1 1 » « - latitude 

 of New York, channels of southward drainage from the terminal moraines <>l" Long 

 island, Martha's Vineyard, Nantuckel and Cape Cod, crossing their frontal plains 

 modified drift and continuing beneath the -e :i . Bhow that 1 1 1 i - part of the coast was 

 higher when these moraines were fprmed than now; and, as no post-glacial marine 

 beds are found there, we may infer that no subsequent sinking bas ;it any time carried 

 tlii.- tract below its present level. It therefore seems probable that while- the ice sheet 

 was retreating from it- terminal moraine on Staten island, past the Catskills and along 

 the Hudson and Champlain valley, the alevation ot the coastal plain outside the Nar- 

 rows, doubtless -till retaining a hundred feet or more of it- for rly very great alti- 

 tude above the sea, and the contemporaneous depression of the region toward the north, 

 known to have been more than five hundred feet below the present sea level at Mon- 

 treal, caused the Hudson valley from Manhattan island northward to 1" cupied by 



a lake, held in by the northern barrier of the receding ice-sheet, and outflowing to the 

 sea over the now submerged plain off Sandy Hook. Since the departure of the ice, a 

 see-saw movement, further depressing the mouth of the Hudson and again uplifting 

 the country northward, has determined the present courses of drainage. 



Returning to the fiord of the Saguenay, cut in the very hard Laurentian gneiss and 

 granite, and comparing it with the shorter submerged fiord of tin' Hudson, cut in soft 



Tertiary (days, it i- obvious that a much longer time was required for tl rosion of 



the Saguenay gorge and the similar fiords of all the coast from Maine to Greenland, 

 and also from the Columbia to Alaska; but still thi> work was not geologically very 

 long, else these valley.- would have become widened, being bordered by gentle slopes 

 instead of Bteep fiord walls. Professor Hitchcock has called attention to the general 

 absence of Tertiary formation- alone; these northern shores of our continenl as proof 

 that the land was higher than now throughout the whole Tertiary era. N'o coastal 

 Pliocene formations are known north of the Carolina-. Thence to the Arctic ocean 

 the present land surface seems to have been nowhere submerged during the Pliocene 

 period : but, on the contrary, evidence of great elevation is afforded by the stream- 

 eroded indentations of Pamlico and Albemarle Bounds and Chesapeake and Delaware 

 hay-, while the vastly older northern coasts are sharply incised by the deep but nar- 

 row fiords. This erosion was probably effected during a period of extraordinary ele- 

 vation, when the northern part of this continent was uplifted as a plateau much above 



previous or present height ; and this uplift seems to have occurred earlier and to 

 have lasted longer in far northern latitude.- than in the vicinity of New York-. The 

 Hudson fiord indicates that it culminated near the close of the Pliocene period, initiat- 

 ing the Quaternary glaciation. 



In the interior of the continent, evidence of -imilar preglacial elevation and of de- 

 pression during the Glacial period is afforded by the basins of the ureal Laurentian 



lake- The origin and history of th basins have been well studied by Newberry, 



( 'lay pole, Spencer, Drum mond, and other-. In the light of their investigations let us 

 briefly the geologic records of tl scillatione of this area : 



Tie- very ureat disturbances of the region on the west in elevation of the Cordille- 

 ran mountain i m<e the Cretaceous period, make it impossible to identify 



there the cour f the larger tributaries to the mediterranean I which 



Btretched from the Gulf of Mexico to the latitude of Athabasca and Great Slave 



