Lowest and Highest Points in Rock Island County
Low elevation: <540 feet above mean sea level
Place: Mississippi River
7.5' quadrangle name: Blanchard Island
PLSS: 4-34-16N-6W
Geology: Cahokia Alluvium in river valley
High elevation: >810 feet above mean sea level
Place: Unnamed hilltop
7.5' quadrangle name: Reynolds
PLSS: 4-31-16N-2W
Geology: Illinoian Kellerville till upland
Area: 447.32 square miles
Total relief (approximate): 270 feet
Average percent slope: 1.50
Updated 05/27/2011 SLD