Dfift in Minneapolis, Minn. — Upham. 293 
limestone and St. Peter sandstone. But east of the University 
and for three miles northward, the river originally flowed at a 
considerable distance east of its present course, the old river 
bed being marked by a continuous tract of shallow peat near 
the eastern limit of the modified drift. 
CHANNELS OF DRAINAGE FKOM THE MELTING ICE-SHEET. 
In the southeast part of these gravel and sand plains, much 
of their original deposit was removed by the rivers coursing 
away from the melting icefields; but since the full departure 
of the ice upon this area, little further erosion has taken place. 
The deserted water courses vary in size up to widths of a 
quarter or third of a mile, with depths of 25 to 43 feet below 
the remaining plains and plateaus. They indicate a somewhat 
prolonged halt of the receding ice border near the western lim- 
its of the city. 
A less permanent course of outflow of a stream from the 
retiring ice is traced along a distance of about two miles south- 
eastward from near the east end of the Lowry hill esker; and 
it apparently represents the incipient glacial river which dur- 
ing the farther recession of the ice border, having become then 
a much larger stream, formed that esker series. Beginning at 
and close east of the intersection of Eighth (Chicago) avenue 
and Twenty-sixth street, this very interesting water course, of 
unequal depths, from 5 to 20 feet, and in part 40 feet, below 
the level of the plain on each side, and having a variable width, 
from 200 or 300 feet to about 1,600 feet, passes crookedly 
south-southeast to the intersection of Cedar avenue and Thir- 
ty-seventh street, where it opens into one of the broad river 
courses before described. The deepest and widest part of this 
singular channel is occupied by Powder Horn lake, some T.500 
feet long and 200 to 600 feet wide, nearly 40 feet below the 
general level, and probably 10 to 15 feet deep. But at some 
places before coming to this lake, and again less than a quarter 
of a mile southeast from it, the channel rises almost to the 
plain level. I cannot doubt, however, that through all its ex- 
tent it was gullied by a torrent of water discharged from tlie 
ice-border during its retreat across this distance. 
