342 



Chamberlin (10), Upham (125. 128), and Spencer (94) have postulated 

 a preglacial outk^t 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 

 lapids, 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 

 ]\Iine 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 

 (Juincy, 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 i)resent junction of the Osage and Missoiiri\" 



■"See bibliosraphy, 7. 12, 15, 41, 71, 81, 90, 10.3, 118, 1.30. 



* For reforeDces on the tributaries of the JNIississippi see : 1. 2. 3. 7, 8. 14, 15. 

 ]6.. 25. 30, 33, 41, 44, 45, 46, 57, 58, 62, 64, 68, 70, 71, 81, 90, 103, 118, 14,6. 



