Low Elevation
< 420 feet above mean sea level
Low Place
Illinois River
Low Quad Name
Cooperstown
Low PLSS
3-33-17N-13W
Low Geology
Cahokia Alluvium in river valley
High Elevation
> 680 feet above mean sea level
High Place
Unnamed hilltop
High Quad Name
Clear Lake
High PLSS
3-14-18N-11W
High Geology
Loess over Glasford Till upland
Area
379.55 square miles
Total Relief
260 feet
Percent Slope
0.96%