Upham.] 
452 
[Jan. 1, 
Saint Louis, thence westward nearly to the junction of the Re- 
publican with the Kansas river, thence northward through eastern 
Nebraska and north-northwest through South Dakota, bending 
from this course about thirty miles west of Bismarck, thence pass- 
ing westerly through northern Montana, Idaho and Washington, 
reaching the Pacific ocean not far south of Vancouver island. It ex- 
tended beyond the Ohio river only for short distances in the vicinity 
of Cincinnati ; but the Missouri river lies mainly within the gla- 
ciated area. On the Mississippi river three hundred to four hun- 
dred and fifty miles north of the boundary of the ice-sheet where 
it reached farthest south, a large driftless area including southwest- 
ern Wisconsin and parts of adjoining states escaped glaciation. In 
the Rocky mountains, the Cascade range, and the Sierra Nevada, 
ice-fields of great extent were accumulated along distances of 
-seven hundred to eight hundred miles south from the border of the 
continental ice-sheet, to latitude 37° S. ; but no evidences of such 
local glaciation south of the ice-sheet are found in the Appalachian 
mountains. 
Upon British America the directions of the glacial striae and 
transportation of the drift show that there were two general ice- 
sheets, one reaching from Newfoundland and Labrador to the 
Rock} T mountains and the Arctic ocean, having its greatest thick- 
ness over the Laurentian highlands and James bay, with outflow 
thence to the east, south, west, and north ; and the other west of 
the Rocky mountains, covering British Columbia, attaining a max- 
imum thickness of about one mile, and outflowing south into the 
United States, west into the Pacific ocean, and northward to the 
upper part of the Yukon basin. The glaciers of the Rocky moun- 
tains were doubtless confluent with these ice-sheets, so tnat at the 
time of maximum extent of the ice it was continuous from the At- 
lantic to the Pacific, covering approximately 4,000,000 square 
miles of this continent. 
Half as large an area was ice-covered in Europe, the principal 
center of outflow being the plateau and mountains of Scandinavia, 
whence the ice moved west and north into the Atlantic, southward 
over northern Germany, and eastward over a large part of Russia. 
Smaller ice-sheets were formed upon Scotland and Ireland, and 
these became confluent with each other and with the Scandinavian 
ice which crossed the present bed of the North Sea to the borders 
of Great Britain. Glaciers also were far more extensive than now 
