402 
GLACIAL DRIFTS IN MINNESOTA 
age because it is deeply leached and much eroded relatively, or to 
ascribe to the Kansan till a “younger” origin, because it is relatively 
little leached. It also would not be impossible in return for repeat¬ 
ed inquiry about “gumbotil” and “Iowan drift” in Minnesota to 
find some small phenomena which under a willing imagination 
could be made to appear to show that they are here. Under 
broader consideration however there is no evidence or criteria 
that has weight bearing affirmatively on them as yet, in Minnesota. 
The main body of the Kansan drift appears to lie in Iowa as 
compared to the main body of the Wisconsin Kewatin drift that 
lies, in Minnesota. Of the moraines of the latter, eight main 
moraines in Minnesota cross into Iowa. Of these, four are out¬ 
side and four just inside the position of the glacier as shown on 
the map, plate xxxvi. Four, or more, moraines close across the 
Minnesota River above its great south angle, and as many also 
across the Red River valley. Thus by moraines, an estimate of 
half the glaciers’ action was while it ended in Iowa, counting the 
period of advance as nothing, and twice as much drift may lie 
in Minnesota as Iowa, in depth. Such an estimate has no force 
except to introduce the idea as to why the main thickness of the 
Wisconsin drift appears to be in southern Minnesota rather than 
south of it. The Kansan till coming presumably from equally 
far north extended so much farther south that, by comparison 
with the Wisconsin drift the main body of its mantle should be 
found in Iowa, and, in fact, appears from all accounts, to be there. 
As to an Iowan drift between them, the same comparison would 
lead to an expectation that its main body lay as much in Minnesota 
as in Iowa, and the finding of no evidence of it has been a very 
intense problem. 
The seemingly very rapid advance of glaciers in Minnesota, as 
compared to the hesitating and long drawn-out succession of re¬ 
advances during recessional substages is an hypothesis that may be 
modified by experience in nearby districts, but here there is lack 
of evidence that the glacier made moraines during its advance to 
maximum extension except in north-central Minnesota, where the 
Wisconsin Kewatin glacier overrode its own. In that district, how¬ 
ever, not enough work has been done to be entirely satisfactory, 
as there may be many phenomena in it that are not yet known. 
