Problems, Middle Mississippi River Region, Pletstocene Time 201 
MISCELLANEOUS TERRACES IN ILLINOIS 
SOUTH OF ST. LOUIS 
Several streams on the Illinois side of the Mississippi River 
south of St. Louis exhibit, in addition to the Festus Terrace, 
other terraces. In each of the streams, where they have been 
observed, they have approximately the same gradient as the 
stream with which they are associated. These stream terraces seem 
to be quite independent of one another. Their elevations 
at their mouths are not found to be concordant. The ter- 
races appear to have been developed in each tributary individually 
when the waters of the tributary were receiving greater volumes 
of sediment than they are at the present. Such a terrace was 
studied in the lower portion of the Kaskaskia River and it seems 
probable that further study would show that the terrace con- 
tinued for a considerable distance upstream. Clear Creek, Union 
County, Illinois, also has such a terrace. Several other tribu- 
taries of the Mississippi River on the Illinois side display two 
terrace levels near their mouths, one of which can be correlated 
to the Festus Terrace; but not the other, which is regularly 
higher than the Festus Terrace. 
Time was not available to give this set of terraces much 
detailed study, but it seems to be established that each stream 
developed its own terrace, uninfluenced by adjacent streams, and 
that each terrace appears to have its own gradient and its own 
Summit level, These terraces are not, then, fragments of a single 
flood plain, as is the case of the Festus Terrace; but they are 
rather a group of terraces, of which the one along the Kaskaskia 
River may be taken as a type. 
TERRACE SUMMARY 
There are three extensive terraces that can be observed in 
the Middle Mississippi River Region. 
1. The Festus Terrace, a former flood plain whose rem- 
nants may be traced on both sides of the Mississippi from Cape 
