254 ROLLIN T. CHAMBERLIN 



pronounced. These, with the steep drop-off faces on the east and 

 northeast sides, give the general direction of movement, but for more 

 exact data recourse must be had to the strise. On the hill west of 

 Taylor's Falls the prevailing striae read in the neighborhood of S. 88° E., 

 showing that the ice moved nearly due east here. In Senator Dee- 

 don's yard, a mile and three-quarters to the north, they trend N. 82 E. 

 Farther north, on the opposite side of the road, the following were 

 recorded in order about a quarter of a mile apart : N. 73 E., N. 72 E., 

 and N. 65 E. Across the river, two miles farther north-northeast, 

 scratches were found reading N. 57 E. These varied, but pro- 

 gressively changing, directions put together on the map, show very 

 prettily how the ice of the gray drift spread out near its outer 

 border until, in places it advanced nearly due northeast. On some 

 of the less exposed portions of the roches strise of the Superior ice are 

 still to be seen. 



POSTGLACIAL PHENOMENA 



Since the Kewatin ice-sheet retreated, the region has undergone 

 some interesting changes, due to erosive action, chiefly that of the 

 St. Croix River. As to what may have been its preglacial course, 

 this region offers little in the nature of a clue. There may have been 

 a preglacial channel past Dresser Junction, and along Horse Creek 

 valley to the Apple River, which lower down empties into the present 

 St. Croix. While the cut between the diabase hills, one and a half 

 miles north of Dresser Junction, was very likely a sluice-way for waters 

 from the melting red ice farther north, to the ponded area, it does not 

 appear to be low enough to form part of a river course before the area 

 just north of it was built up by the thick deposits of drift. 



During the early stages of the river's postglacial history, when great 

 floods of water descended the St. Croix from Lake Duluth, much of 

 the flat land east and south of Osceola was temporarily covered, and 

 the already nearly flat area appears to have been still further leveled 

 by sedimentation. Later the river retired to a more definite course 

 which soon deepened. Since the first well-marked course was formed, 

 the stream between Taylor's Falls and Osceola where the most 

 Keweenawan trap-rock was encountered, has migrated westward 

 down the slopes of hard diabase, and cut away the less resistant 

 sandstone and shale. The slopes on the Wisconsin side, opposite 



