The bedrock exposed in the Big Spring quadrangle of Missouri comprises Late Cambrian and Early Ordovician aged dolomite, sandstone, and chert. The sedimentary rocks are nearly flat lying except where they are adjacent to faults. The carbonate rocks are karstified, and the area contains numerous sinkholes, springs, caves, and losing streams. This map is one of several being produced under the U.S. Geological Survey (USGS) National Cooperative Geologic Mapping Program to provide geologic data applicable to land-use problems in the Ozarks of south-central Missouri. Ongoing and potential industrial and agricultural development in the Ozarks region has presented issues of ground-water quality in karst areas. A national park in this region (Ozark National Scenic Riverways, Missouri) is concerned about the effects of activities in areas outside of their stewardship on the water resources that define the heart of this park. This task applies geologic mapping and karst investigations to address issues surrounding competing land use in south-central Missouri. This task keeps geologists from the USGS associated with the park and allows the park to utilize USGS expertise and aid the NPS on how to effectively use geologic maps for park management. For more information, see: http://geology.er.usgs.gov/eespteam/Karst/index.html