Low Elevation
< 520 feet above mean sea level
Low Place
Spoon River
Low Quad Name
London Mills
Low PLSS
4-34-13N-2E
Low Geology
Cahokia Alluvium, river valley
High Elevation
> 870 feet above mean sea level
High Place
Pilot Knob
High Quad Name
Oneida
High PLSS
4-26-13-N-2E
High Geology
Thin Hulic Till member over Pennsylvanian Carbondale Formation
Area
712.37 square miles
Total Relief
350 feet
Percent Slope
1.33%