Tractor-sized sinkhole
The following links contain more information on karst:
WISCONSIN:
- Avoid that Sinking Feeling: Sinkholes, Limestone, and Groundwater Contamination (PDF), University of Wisconsin–Madison, Division of Extension Institute of Natural Resources
- Final Report of the Northeast Wisconsin Karst Task Force (PDF), University of Wisconsin–Madison, Division of Extension
- Drinking Water and Groundwater, Wisconsin Department of Natural Resources
FLORIDA: Sinkholes in Florida, Florida Department of Environmental Protection
ILLINOIS: Karst Landscapes of Illinois, Illinois State Geological Survey
PENNSYLVANIA: Sinkholes in Pennsylvania, Pennsylvania Department of Environmental Protection
OTHER: Karst Waters Institute
