Lowest and Highest Points in Grundy County
Low elevation: <510 feet above mean sea level
Place: Illinois River
7.5' quadrangle name: Seneca
PLSS: 3-30-33N-6E
Geology: Cahokia Alluvium in river valley
High elevation: >700 feet above mean sea level
Place: Unnamed hilltop
7.5' quadrangle name: Stavanger
PLSS: 3-6-34N-6E
Geology: Ransom Moraine
Area: 426.49 square miles
Total relief (approximate): 190 feet
Average percent slope: 0.54%
Updated 9/30/2009 JKH