INVESTIGATION FOR HYDRAULIC CONDUITS INVOLVED IN SINKHOLE FORMATION THROUGH THE USE OF INTEGRATED SURFACE AND BOREHOLE GEOPHYSICS

摘要

The Nachusa Grasslands Conservancy is located near Franklin Grove in northern Illinois. It was used previously for agriculture and is currently undergoing restoration into a natural prairie. A sinkhole, ~40m in diameter, exists in the northern portion of this area. At this location Ordovician age dolomite subcrops beneath St. Peter sandstone and several meters of unconsolidated sand, gravel and clay. Geophysical surveys were deployed to determine the location and nature of hydraulic conduits related to the sinkhole's formation.