Lowest and Highest Points in Cass County
Low elevation: <420 feet above mean sea level
Place: Illinois River
7.5' quadrangle name: Cooperstown
PLSS: 3-33-17N-13W
Geology: Cahokia Alluvium in river valley
High elevation: >680 feet above mean sea level
Place: Unnamed hilltop
7.5' quadrangle name: Clear Lake
PLSS: 3-14-18N-11W
Geology: Loess over Glasford Till upland
Area: 379.55 square miles
Total relief (approximate): 260 feet
Average percent slope: 0.96%
Updated 9/29/2009 JKH