Some Problems of the 
Middle Mississippi 
River Region 
During Pleistocene Time 
PerciIvAL ROBERTSON 
INTRODUCTION 
The area comprised in this study lies along the Mississippi 
River and its tributaries in parts of the states of Missouri and 
Illinois. It includes a distance of approximately a hundred miles 
down stream from St. Louis to the vicinity of Cape Girardeau, 
Missouri, and a somewhat shorter distance up the Mississippi, 
Missouri, and Illinois rivers. This area has been called for the 
Purpose of this report the Middle Mississppi River Region. 
Figure 1 shows the principal streams in this area. 
The Pleistocene deposits in this region include drift, its asso- 
ciated outwash and valley train material, lake deposits, and loess. 
This particular report is concerned principally with the drift, 
the outwash from it, and the lake deposits whose remnants are 
seen as terraces along the main streams and more particularly 
in their tributaries. An abstract of the work done on the 
loess has been published elsewhere ' 
The author is indebted to a host of individuals who have 
Studied this region previously. A list of all those to whom 
