now by a moderate degree of refrigeration, are found to extend 
over all the North Atlantic region, including also Greenland, Ice- 
. land, northwestern Europe, and even Spitzbergen 1 . We there- 
fore must conclude that these climatic changes probably have 
depended in common on further reaching causes and conditions, 
which may yet have consisted chiefly in geographic movements 
of elevation and subsidence, with their effect on the general 
oceanic circulation. 
Between the time of departure of the ice-sheet, at the close of 
the Glacial period, and the time of northward migration of the 
southern marine fauna, a very imp >rtant upward movement had 
taken place, affecting the eastern provinces of Canada and the 
northern two thirds of New England, extending south to the lat- 
itude of Boston. To speak more strictly, however, this uplifting 
of our part of the continent was limited southeastwardly by a line 
drawn approximately from the mouth of the Hudson northeast to 
Boston and onward through Nova Scotia. When the ice-sheet 
was withdrawing from this region, the country south of this 
line stood somewhat higher than now, as is shown by the chan- 
nels of streams that flowed away from the melting ice and ran 
across the modified drift plains which form the southern shores 
of Long Island, Martha’s Vineyard, Nantucket, and Cape Cod. 
A subsequent depression of the land there, continuing perhaps to 
the present time, has brought the sea into these old river courses. 
But north and northwest from this line the lan l at the time of re- 
cession of the ice-sheet was lower than now, and the coast and 
estuaries were more submerged by the sea. At Boston and north- 
ward to Cape Ann the depression appears to have been no more 
than from ten to twenty-five feet. Eossiliferous beds overlying the 
till show that the vertical amount of the marine submergence in 
the vicinity of Portsmouth was about 150 feet ; along the coast of 
Maine, from 150 to about 300 feet ; on the northwestern shore of 
Nova Scotia, about 40 feet ; thence increasing westward to about 
200 feet in the basin of the Bay of Chaleurs, 375 feet in the St. 
Lawrence valley opposite the Saguenay, and 520 feet at Montreal ; 
300 to 400 feet, increasing from south to north, in the basin of 
Lake Champlain; about 275 feet at Ogdensburgh, and 450 feet 
1 (James Geikie, Prehistoric Europe, Chapters xx and xxi, 1881. Warren Upham, 
“On the Cause of the Glacial Period,'’ Am. Geologist, vol. vi, pp. 327-339, Dec., 1890. 
