Low Elevation
< 445 feet above mean sea level
Low Place
Illinois River
Low Quad Name
Spring Valley
Low PLSS
3-19-33N-1E
Low Geology
Cahokia Alluvium, river valley
High Elevation
> 910 feet above mean sea level
High Place
unnamed hilltop
High Quad Name
Sublette
High PLSS
3-5-36N-1E
High Geology
La Moille / Paw Paw Moraines
Area
1137.41 square miles
Total Relief
465 feet
Percent Slope
1.03%