WARREN ["IMIAM — THE CHAMPLAIN SUBMERGENCE. 509 



of Boston and northeastward to cape Ann ; about 150 feet in the vicinity of Ports- 

 mouth, New Hampshire ; from Mo to about 300 feet along the coast of Maine and 

 southern New Brunswick; aboul to feet on the northwestern shore of Nova Scotia ; 

 thence increasing westward to 200 feet in the Bay of Chaleurs,375 feet in the Saint 

 Lawrence valley opposite the Saguenay, and 520 feet at Montreal ; 300 to 400 feet, 

 increasing from smith to north, along the basin of lake Champlain ; about 275 feet 

 at < >gdensburg, and 450 feet near the city of ( Htawa ; .'Kill to 500 feet on the country 

 southwest of James bay ; in Labrador little at the south, hut increasing northward 

 to 1,500 feet at Nachvak, according to [)r. Robert Bell, and in northern Greenland 

 and Grinnell land from L,000 to 2,000 feet. 



That the land northward from Boston was so much lower while the ice-sheet was 

 being melted away is proved by the occurrence of fossil mollusks of far northern 

 range, including l.nin arctica, Gray, which is now found living only in arctic seas 

 where they receive muddy streams from existing glaciers and from the Greenland 

 ice-sheet. This species is plentiful in the stratified clays resting on the till in the 

 Saint Lawrence valley and in New Brunswick and Maine, extending southward to 

 Portsmouth, New Hampshire. But it is known that the land was elevated from 

 this depression to about its present height before the sea here became warm and the 

 southern mollusks, which exist as colonies in the Gulf of Saint Lawrence, migrated 

 thither, for these southern species are not included in the extensive lists of the 

 fossil fauna found in the beds overlying the till. 



In the Saint Lawrence basin these marine deposits reach to the southern end of 

 lake Champlain, to Ogdensburg and Brockville, and at least to Pembi'oke and Allu- 

 mette island, in the Ottawa river, about 75 miles above the city of Ottawa. The 

 isthmus of ( Ihiegnecto, connecting Nova Scotia with New Brunswick, was submerged, 

 and the sea extended 50 to 100 miles up the valleys of the chief rivers of Maine and 

 New Brunswick. 



From the Champlain submergence attending the departure of the ice the land 

 was raised somewhat higher than now; and its latest movement from New Jersey 

 to southern Greenland has been a moderate depression. The vertical amount of 

 t his post-glacial elevation above the present height and of the recent subsidence on 

 all the coast of New Jersey, New England and the eastern provinces of Canada is 

 known to have ranged from L0 feet to a maximum of at least 80 feet at the head of 

 t he hay of Fundy, as is attested in many places by stumps of forests, rooted where 

 they gre.Wj and by peat beds now submerged by the sea. 



At the time of final melting of the ice-sheet this region, which before t he Lee age 

 had stood much higher than now. was depressed, ami the maximum amount of its 

 subsidence, as shown by marine fossils at Montreal and northwestward to Hudson 

 bay, was 500 to 600 feet. Subsequently our Atlantic coast has been re-elevated to 



a height probably K' > feel greater than now; and during the recent e] h its latest 



oscillation has been again downward, as when it was ice-covered^ The rate of de- 

 pression since the discovery of America has probably been I to 2 feet, or less, in a 

 hundred years. I n t he hasin of 1 1 udson bay, however, the observations of] >r. Bell 

 show that the re-elevation from the Champlain submergence is still in progress, its 

 rate, according to his estimate, reaching probably 5 to 7 feet during each century. 



Turning to the glaciated regions of Europe, we find similarly thai the countries 

 which wire ice-covered, after having been much higher before the ice accumu- 

 lation, as shown by fjords, were depressed somewhal below their present height 

 when the ice disappeared. The supposed great submergence, however, up to 1,21 



l.\ I \ -Bi ii Soc, V»l., Vol. 3, 1891. 



