BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 5, pp. 531-548 April 26, 1894 



PLEISTOCENE PROBLEMS IN MLSSOURI^i^ 



BY J. E. TODD 



{Read before the Society December 29, 1893) 



CONTENTS 



Page 



Introduction 531 



The Preglacial Formations 532 



General geologic and topographic Features 532 



The Bowldery Drift 533 



Its Character 533 



Distribution of Bowldery Drift , 534 



The Loess or Loamy Clay 535 



Its Character 535 



The Limit of the Loess and associated Deposits 536 



Terraces, Ancient Channels and Rapids 537 



Relation of present Topography to the Pleistocene Formations 540 



Hypotheses as to the Origin of the Pleistocene Formations 541 



Discussion of the Subglacial Hypothesis 541 



The Hypothesis stated 541 



Objections to the Hypothesis 542 



The Lacustrine Theory 543 



The Theory stated 543 



0))jections to the Theory 545 



The Fluviatile Hypothesis 545 



The Hypothesis stated 545 



Objections to the Hyi)othesis 546 



Conclusions 548 



Introduction. 



As one portion of the country after another lias had its glacial geology 

 cleared up in recent years by the enthusiastic research which later 

 theories have inspired, doubtless more than one glacialist has turned his 

 eyes toward Missouri, which exhibits a wider area of extramorainic drift 

 than is found in any other state, and shows northern drift at the remotest 

 point from its orio-inal source, unless, possibly, Kansas takes the palm in 

 these respects. It is, therefore, with satisfaction that I attempt a brief 



*Puhlislied witli the permission of Arthur Wiuslow, State Geologist of Missouri. 

 LXXIV — IkTi.t.. GKOt,. Soc. Am., Voi-. 5, 1893. (531) 



