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Knox County
Low elevation: <520 feet above mean sea level
Place: Spoon River
7.5' quadrangle name: London Mills
PLSS: 4-34-9N-2E
Geology: Cahokia Alluvium in river valley
High elevation: >870 feet above mean sea level
Place: Pilot Knob
7.5' quadrangle name: Oneida
PLSS: 4-26-13N-2E
Geology: Thin Hulic Till member over Pennsylvanian Carbondale Formation
Area: 712.37 square miles
Total relief (approximate): 350 feet
Average percent slope: 1.33%
State of Illinois | Illinois Department of Natural Resources | University of Illinois