The Keivccnawan in Minnesota. — Elftman. 107 
N., R. iiW., connects the Saint Louis with the Stony river. 
The southern head of the Stony and that of the Cloquet river 
are on the same level. The sources of the Baptism and Isa- 
bella rivers are upon' the same level in a valley which cuts 
through the Itasca-Highland moraine. The stratified de- 
posits in this valley south of the moraine are composed partly 
of material brought from the region north of the moraine, 
indicating a drainage toward the south. These are the chief 
glacial rivers, others of minor importance show the same 
phenomena as those just mentioned. 
GLACIAL EROSION. 
Glacial erosion in the greater part of this region did not 
extend much beyond the removal of the decomposed surface 
rock. It was most active along the main direction of the ice 
lobes. The change in the topography is not very marked. 
The tendency to change the V-shaped valleys of the pre- 
glacial erosion to U-shaped valleys is well exhibited along the 
north shore of lake Superior where the low dipping strata are 
cut oflf near the side of the valley. The Sawteeth mountains, 
which are chiefly due to pre-glacial faulting, w^ere not changed 
to any extent beyond the rounding off of the edges and sides 
facing the direction from which the ice came. The greater 
part of the rock which makes up these hills is a medium 
grained compact diabase, which resists weathering better than 
the amygdaloidal rocks above it, which have been largely re- 
moved by glacial action. 
The rocks forming the present surface are generally quite 
fresh. Yet in some areas the basal gabbro is entirely decom- 
posed and does not appear to have been subjected to exten- 
sive erosion. The existence of these areas may be due to 
deep local pre-glacial weathering. When the region was 
levelled ofif by glaciation the low-er portion of the altered rock 
remained in place. 
SUMMARY. 
The evidence presented by the structure and composition 
of the glacial drift, the striae, and other glacial phenomena, 
show that the drift deposits were formed by two lobes, one of 
which moved in a general southwesterly direction through 
