835 



The r^REGLAciAi. Valleys of the Upper Mississippi and its 

 Eastern Tributaries. 



IIarey M. Ci.Ei[. 



So far as the writer is aware, there has been no attempt to compile 

 a map showing the results of researches upon the preglacial drainage of 

 the region indicated in the title. The following paper addresses itself to 

 that task, together with a brief discussion of the reason for believing that 

 certain streams shown on the map were preglacial. Only the briefest out- 

 line can be given in this short discussion, which merely undertakes to 

 pioneer the large field lying before it. 



The attempt has been made to map accurately the preglacial channels 

 of the area in question, but this may not always have been attained, for 

 several reasons. The literature is not adequate in all the fields of the area, 

 and often the statements made are not so clear as might be desired. The 

 word "probable" is very frequently used and renders mapping difficult, 

 if not impossible. Occasionally, authors differ, and in such cases the one 

 which seemed to be the better authority is followed, and the dissenting 

 theory mentioned in the text. No attempt has been made to give a critical 

 discussion of the different theories. Any reader who may desire more 

 detailed information than this paper furnishes can find all that is of im- 

 portance In the accompanying bibliography,^ or he may look there for coj"- 

 rection or verification of any points in the discussion with which he maj' 

 disagi"ee. 



The greater portion of the region covered in this paper is so deeply 

 l)uried in drift that only the major details of the ancient preglacial topog- 

 raphy are apparent. The multiplicity of minor topographic details that 

 give final expression to the landscape are so completely buried from sight 

 that it may never be known how the ancient surface appeared before the 

 advent of the glacier. Only by a multiplicity of boi'ings could a general 

 idea of the details of that buried topography be obtained, and that is im- 

 possible except wIk'I'c some dceji-spnted natural resource induces men to 

 sink deep wells. Tims iiiiinmerablc small valleys have been obliterated and 



'Not published here. 



