394 
GLACIAL DRIFTS IN MINNESOTA 
transmitted stresses to the underground evidently until masses of 
the ground gave way and were transported. It is quite clear 
that the advancing ice picked up boulders and gravel beds in some 
such way and that it gave more material to throw out at the melt¬ 
ing front as outwash and kames. In its retreatal substages, how¬ 
ever, the Kansan glacier was much like the Nebraskan had been, 
and was seemingly riding smoothly on clayey, wet ground moraine 
or on bare immovable rock surface. The bed-rock surfaces that 
bear the striations of the Kansan glacier have a polished, pitted 
aspect that is termed clay-polish. 
Retreatal moraines of the Kansan glacier were no doubt of the 
low-lying, clay-moraine type, such as do not blockade valleys 
much and there was also evidently an absence of high -outwash 
plains so that the main rivers could at once resume their courses 
after the ice was gone. Post-Kansan erosion made many gravelly 
terraces along secondary streams, but the main river courses ap¬ 
pear to have silted up when filled at all. Kansan till lies at and 
below river-level of the Minnesota-Mississippi junction now in the 
pre-Kansan and post-Kansan valley there as it does also on the 
upland, but is much eroded through in both places. The Kansan 
till remnants are often strikingly thick and it appears, in fact, as 
the “great drift” sheet as compared either with the Nebraskan or 
the Wisconsin Kewatin drifts. Its morainal belts have, however, 
not been yet traced. 
The Illinoian glacial drift in Minnesota is largely covered by the 
Wisconsin Patrician glaciers’ work. A small part of it is exposed 
at the surface in Dakota and Washington counties (Nos. 9 and 
11, plate xxxiv) ; and there is more of it in Wisconsin. For 
simplicity’s sake, only the Patrician is shown on the map, (plate 
xxxiv) ; and the Kewatin and Labradorian of the Wisconsin stage 
are omitted. (See maps plate xxxv and xxxvi for the latter). 
The Illinoian drift here is most like the Labradorian of the 
Wisconsin stage, but the Patrician is also a “red” drift, so that 
where this and the Illinoian lie together the distinction is mainly 
that of age, “young red” and “old red,” with also a soil zone be¬ 
tween them in local erosion exposures, as at Taylors Falls (No. 12, 
plate xxxiv). In form, the Illinoian glacier is to be compared 
with the Wisconsin Labradorian glacier, both being long tongues 
