337 



Huron, N. D., where there is a col aud a constriction in tlae James river, 

 a preglacial divide, over which the reversed headwaters of that stream now 

 nm southward. From Huron eastward its location is a matter of specula- 

 tion backed up with slender evidence. From here it may have turned south 

 across the present Mississippi valley somewhere near "military ridge," as 

 Hershey (46) would have it, and then eastward, or it may have turned 

 north some distance east of Huron along the east edge of the basin of the 

 Red river, but this will be discussed more fully later. "Between the Rock 

 river drainage line and Lake Michigan there is a somewhat less elevated 

 belt of limestone, which extends curvingly in a direction east of south 

 into western Indiana." (Leverett, 64:16.) Somewhere in eastern Illinois 

 or western Indiana a spur ran south, probably near the present divide be- 

 tween the Wabash and Illinois system separating the preglacial as well as 

 the present basins. The location of the divide north through Wisconsin is 

 not well known, l>ut there is no doubt that it was east of the present "drift- 

 less area." 



Even if it were possible and profitable, space does not adiuit of a de- 

 tailed discussion of secondary divides, which can generally be inferred 

 from the location of the preglacial valleys. After calling attention to the 

 fact that the present Mississippi river has evidently a system of drainage 

 widely different from the system or systems which were operative in pre- 

 glacial times within the region now drained by it, Leverett says : "Besides 

 opening a riew channel at each of the rapids, the stream apparently is occu- 

 pying sections of two or more independent preglacial valleys." (64:461.) 



As to the course of the Mississippi above St. Paul, Chamberlain sug- 

 gested, in 1879, that it is post-glacial (19:25.3), but that it probably follows 

 the preglacial channel in short stretches. Hershey, in 1897, agrees with the 

 suggestion. 



Hershey has the following to say concerning the preglacial valley 

 above St. Paul : "The high upland area which trends north and south on 

 its eastern side at some distance from its immediate border, continues 

 without a change for many miles to the north, passing to the east of 

 Lake Phalen. Although deeply covered with drift, it is undoubtedly based 

 on an upland area of rock. To the west of it, and in the direct line of con- 

 tinuation of the old Mississippi valley, there is a topographical depression 

 which trends for many miles to the northwest. It is occupied in places by 

 lakes, tile most important of which is lake Phalen. This, in my opinion, 



[22—269881 



