238 Transactions of the Academy of Science of St. Louis 
center, approached the Middle Mississippi River Region from 
the east, but apparently did not cross the river. 
3. Centralian epoch: the principal Illinoian ice front was 
parallel to the Mississippi River in this region. A tongue of ice 
extended across the Mississippi River from about Edwardsville 
to the St. Louis side of the river. Thick deposits of drift were 
- formed in O’Fallon Park, St. Louis. This ice tongue, and prob- 
ably its corresponding moraine, dammed the Mississippi River, 
producing a very extensive lake in which the Cuivre Terrace 
was deposited. 
4. Eldoran epoch: The Wisconsin valley-train produced the 
Festus Terrace, which has been considerably eroded in subse- 
quent time. 
