Upham.J 
314 
[Nov. 4, 
been a very important element, re-enforced probably by con- 
temporaneous greater elevation of the Cordilleran mountain belt 
from the St. Elias range to the Sierra Nevada, in causing these 
mountains and t.he adjoining lower ground to bear very lately, as 
Russell and Becker have shown, extensive glaciers or even ice- 
sheets, which have now disappeared from the southern part of 
this belt and are fast retreating in Alaska. 1 The last 500 or 
1,000 years, according to Russell, have been marked by rapid gla- 
cial recession in the St. Elias region. But during the same or a 
longer time the North Atlantic area has been growing colder, 
gradually excluding the southern mollusks, causing the ice-sheet 
of Greenland to increase again, and giving to that country a 
much less hospitable climate than during the prosperous period of 
the Norse colonies, from 900 to 500 years ago. Both the de- 
crease of the Alaskan glaciers and the increase of cold and of ice 
accumulation in Greenland are attributable, as I believe, to the 
present partial closure of the passage between the Arctic and 
Pacific oceans. 
In another way, however, which is perhaps more probable, 
that is, by assuming that the principal current through the for- 
merly enlarged Bering Strait flowed as now northward, we may 
almost equally well explain the climatic changes of both the 
western Cordilleran belt and the North Atlantic area. Such in- 
creased northward outflow from the Pacific would be subtracted 
from the warm Kuro Siwo or Japan current, the greater part of 
which passes to the east and south along the shores of Alaska, 
British Columbia, and the Pacific States, and would thus tend to 
produce the cold of the recent Cordilleran glaciation. The 
formerly large branch of the Japan current entering the Arctic 
Ocean by Bering Strait would be partly, and probably almost 
wholly, carried thence eastward along the northern coast of 
North America and through its archipelago to Baffin Bay, Davis 
Strait, and the North Atlantic, bringing somewhat milder cli- 
matic conditions to Greenland and to all those shores where the 
1 I. C. Russell, Geological History of Lake Lahontan, U. S. Geol. Survey, Mono- 
graph xi, 1885, p. 273; Bulletin, G. S. A., vol. i, 1890, p. 142; Expedition to Mount 
St. Elias, Alaska, National Geographic Magazine, vol. iii, 1891, pp. 64, 93, 98, 100, 104, 
112, 173. G. F. Bocker, Bulletin, G. S. A., vol. ii, 1891, p. 196. Warren Upham, 
Am. Jour. Science, III, vol. xli, pp. 41, 51, Jan., 1891; Am. Geologist, vol. viii, p. 
150, Sept., 1891. 
