Chamberlin (19), Upham (125, 128), and Spencer (94) have postulated 
a preglacial outlet of Lake Michigan through Illinois to the Mississippi, but 
no such channel has been found. Cache basin in southern Illinois is inter- 
esting. because it may be a portion of the preglacial Ohio, as deposits of 
clay indicate, but why or when it was abandoned is not known (64). 
A glance at the map of Iowa shows a correspondence in location and 
direction between the preglacial and the modern drainage lines. The 
geological survey of the State of Iowa is not yet completed. The breaks 
in the preglacial valleys on the map indicate either that the river is not 
running in a preglacial channel or that it has not been studied. Space 
will not permit a detailed statement as to which of these two facts is 
indicated, but a study of the references will make it clear. In the eastern 
part of the State the preglacial drainage has been obscured by drift and 
the flow of the temporary interglacial Mississippi across them, while in 
the northwest the drift alone has defaced the ancient valleys. 
In Missouri but little study has been devoted to the preglacial condi- 
tions of the State. J. E. Todd (111) has given,the following summary of 
the preglacial drainage in the Missouri Geological Survey: “The Kansas 
River may have flowed at a higher level, which is indicated by the Weston 
rapids, and it may be guessed that its course was eastward as far as 
Chariton County, then possibly northward by the buried channel found in 
Linn County and Putnam County, although that channel may not be deep 
enough. All that is now known is that there were deeper channels in 
Iowa whose beds are lower than the bottom of the present channel of the 
Missouri river near New Frankfort. Reference is made to the Washing- 
ton channel discovered by Calvin, and further discussed by Bain. The La 
Mine and its tributaries may have flowed north and joined it. The Osage 
and Gasconade may have similarly gone northeast into the valley of the 
Illinois, the former by way of the valley of the Auxvasse or Big Muddy 
to the valley of the Salt River and northeast, passing somewhere near 
Quincy, the latter by the lower course of the Missouri. It may be consid- 
ered more likely by some that the Kansas river passed Moberly and joined 
the Osage, or that all these streams may have had nearly their present 
courses to the present junction of the Osage and Missouri*.” 
®* See bibliography, 7, 12, 15, 41, 71, 81, 90, 103, 118, 139. 
*For references on the tributaries of the Mississippi see: 1, 2, 3, 7, 8, 14, 15. 
16. 25, 30, 33, 41, 44, 45, 46, 57, 58, 62, 64, 68, 70, 71, 81, 90, 103, 118, 146. 
