Lowest and Highest Points in Henry County
Low elevation: <560 feet above mean sea level
Place: Rock River
7.5' quadrangle name: Coal Valley
PLSS: 4-19-17N-1E
Geology: Cahokia Allumium, river valley
High elevation: >875 feet above mean sea level
Place: Unnamed hilltop
7.5' quadrangle name: Kewanee South
PLSS: 4-1-14N-4E
Geology: Loess hill over thin Illinois Glasford till over Pennsylvanian Carbondale Formation
Area: 817.22 square miles
Total relief (approximate): 315 feet
Average percent slope: 1.11%
Updated 9/30/2009 JKH