228 The American Geologist. April, i89i 
The outflowing James river was cutting down its channel during 
the retreat of the ice-lobe, and its erosion was so rapid as to pre- 
vent the northern part of lake Dakota from retaining sufficient 
depth to outflow eastward into the south end of lake Agassiz 
when the way was opened b} r the further departure of the ice, re- 
ceding from the Head of the Coteau des Prairies and beginning to 
uncover the Red River valley. A large tract of the sand and silt 
beds of lake Dakota, and of a contiguous glacial lake formed in 
Sargent county, North Dakota, at the time of the Dovre moraine, 
now sends its drainage to the Red river b}' the head stream of the 
Wild Rice, which passes north of the Head of the Coteau and en- 
ters the area of lake Agassiz near Wyndmere. The lowest portion 
of the water-shed on this lacustrine deposit, over which the James 
river would flow east to the Wild Rice river is scarcely ten feet 
above the general level of the James valle}* or twenty-five feet 
above the present level of the James river, being at Amherst on 
the Aberdeen branch of the Saint Paul, Minneapolis and Mani- 
toba Railway, 1,312 feet above the sea. The elevation of the 
upper portion of the lake beds in the vicinity of Oakes, and the 
lack of evidence that the lake waves have acted at any greater 
height upon the adjoining surfaces of undulating till and morainic 
hills, lead to the conclusion that the highest shore line of the 
north end of lake Dakota is not more than 1,345 feet above the 
sea, showing that there was only a shallow expanse of water above 
the plain of lacustrine silt. On the north the depth of the chan- 
nel of the inflowing James river, eroded apparently before the 
glacial retreat could permit an eastward outlet into lake Agassiz, 
indicates that the surfaces of land and water in the James valle}- 
had gained nearly their present relations, lake Dakota being al- 
ready drained away, when the Wild Rice river and the south end 
of the Red River valley were uncovered by the recession of the 
ice-sheet. It is evident, therefore, that the long area of lake 
Dakota has experienced only slight differential changes of level, 
at least in the direction from south to north, since the departure of 
the ice. The James River valley is thus strongly contrasted with 
the northward uplifting that has affected the Red River valley as 
shown by the beaches of lake Agassiz, the highest of which rises 
from south to north about six inches per mile for 30 or 40 miles 
at its south end, but a foot or more per mile within 40 miles far- 
ther north, and indeed has an average northward ascent of about 
