Low Elevation
< 440 feet above mean sea level
Low Place
Illinois River
Low Quad Name
Duck Island
Low PLSS
3-17-23-7W
Low Geology
Cahokia Alluvium, river valley
High Elevation
> 830 feet above mean sea level
High Place
unnamed hilltop
High Quad Name
Washington
High PLSS
3-11-26N-3W
High Geology
Washington Moraine
Area
650.28 square miles
Total Relief
390 feet
Percent Slope
1.22%