Southeastern Minnesota is part of the Upper Mississippi Valley Karst (Hedges and Alexander, 1985) that includes southwestern Wisconsin and northeastern Iowa. Karst lands in Minnesota are developed in Paleozoic carbonate and sandstone bedrock. A significant sandstone karst has developed in Pine County (Shade and others, 2001). Most surficial karst features such as sinkholes are found only in those areas with less than fifty feet of sedimentary cover over bedrock surface (Gao and others, 2002).

Since the early 1980s, the Minnesota Geological Survey and Department of Geology and Geophysics at the University of Minnesota have been mapping karst features and publishing various versions of their results in the form of 1:100,000 scale County Geologic Atlases. In the mid 1990s, the Minnesota Department of Natural Resources was assigned responsibility for the hydrogeology portions of the County Atlases and is now responsible for the karst mapping. Dalgleish and Alexander (1984), Alexander and Maki (1988), Witthuhn and Alexander (1995), Green and others (1997), Shade and others (2001), and Tipping and others (2001) published sinkhole distribution maps for Winona, Olmsted, Fillmore Counties, Leroy Township, Pine and Wabasha Counties respectively. Published Atlases of Washington, Dakota, and the counties of the Twin Cites Metro area contain limited information on sinkhole occurrences.

A karst feature database of Southeastern Minnesota has been developed that allows sinkhole and other karst feature distributions to be displayed and analyzed across existing county boundaries in a GIS environment. The central DBMS is a relational GIS-based system interacting with three modules: spatial operation, spatial analysis, and hydrogeological modules. Data tables are stored in a Microsoft ACCESS 2000 DBMS and linked to corresponding ArcView shape files. The current Karst Feature Database of Southeastern Minnesota was put on a Citrix Window 2000 server accessible to researchers and planners through networked interfaces.

The karst inventory points were point features such as sinkholes, springs, and stream sinks extracted from the karst feature database of Southeastern Minnesota. Both inventory points and karst feature database are updated on regular basis. This research was supported with funding from the Minnesota Department of Health.

karstfeature shows all the major karst features stored in the karst feature database of southeastern Minnesota.

mnkarst overlays the areas with < 50 feet, 50 to 100 feet, and > 100 feet of surficial cover over the areas underlain by carbonate bedrock. This map emphasizes the patchy nature of the thick sediment cover and the importance of site-specific information for land-use decisions.

pinekarst illustrates sinkhole distributions in the sandstone karst areas of Pine county.

Karst feature data sources

Processing steps to develop karst feature database and generate inventory points:

1>. Jan. 2000 - Mar. 2000, Investigate existing documentation concerning the application of the database and study the current operating environment and planned use of the information.

2>. Apr. 2000 - Sept. 2000, Assemble datasets and develop a karst feature database for Winona County.

3>. Oct. 2001 - Dec. 2001, Revise entities, attributes, domains, and keys, relationships, and referential integrities for the karst feature database.

4>. Jan. 2001 - June 2001, Load existing archived karst feature files into the karst feature database and build applications for the karst feature database.

5>. July 2001 - Dec. 2001, Verify database consistency and security and test applications.

6>. Jan. 2002 - June. 2002, Conduct user test to verify attributes and locations of karst features in the database by using applications built for the database. Modify some of the applications and table structures if necessary.

7>. July 2002 - present, Load and convert more data into the database and verify its overall consistency and security. Generate web-accessible karst feature inventory points.

E Calvin Alexander Jr.
Department of Geology and Geophysics
University of Minnesota
Minneapolis, MN 55455
Phone: (612) 624-3517
FAX: (612) 625-3819
E-mail: alexa001@umn.edu

Robert G. Tipping
Minnesota Geological Survey
2642 University Ave. W.
St. Paul, MN 55114-1057
Phone: (612) 624-4780 ext. 226
FAX: (612) 627-4778
E-mail: tippi001@umn.edu

Alexander E.C., Jr., and Maki, G.L., 1988, Sinkholes and Sinkhole Probability: Geologic Atlas of Olmsted County, Minnesota, County Atlas Series C-3, Minnesota Geological Survey, St. Paul, Minnesota, Plate 7.

Dalgleish, J.D., and Alexander, E.C., Jr., 1984, Sinkholes and sinkhole probability: in Balaban, N. H., and Olsen, B. M., eds., Geologic Atlas of Winona County: County Atlas Series C-2, Minnesota Geological Survey, St. Paul, Minnesota, Plate 5.

Gao, Y., Alexander, E.C. Jr., and Tipping, R.G., 2002, The Development of a Karst Feature Database for Southeastern Minnesota, Journal of Cave and Karst Studies, v. 64, no. 1, p.51-57.

Green, J.A., Mossler, J.H., Alexander, S.C., and Alexander, E.C., Jr., 1997, Karst Hydrogeology of Le Roy Township, Mower County, Minnesota: Minnesota Geological Survey Open File Report 97-2, scale 1:24,000, St.Paul, MN, 2 plates.

Green, J.A., 2003, Karst Features: Geologic Atlas of Mower County, Minnesota, County Atlas Series C-11, Part B, Minnesota Department of Natural Resources, St. Paul.

Hedges, J., and Alexander, E.C., Jr., 1985, Karst-related features of the Upper Mississippi Valley Region: Studies in Speleology, v.6, p. 41-49.

Shade, B.L., Alexander, S.C., Alexander, E.C., Jr., and Martin, S., 2001, Sinkhole distribution, Depth to bedrock, and Bedrock topography: Geologic Atlas of Pine County, Minnesota, County Atlas Series C-13, Minnesota Geological Survey, St. Paul, Minnesota, Plate 6.

Tipping, R.G., Green, J.A., and Alexander, E.C., Jr., 2001, Karst Features: Geologic Atlas of Wabasha County, Minnesota, County Atlas Series C-14, Minnesota Geological Survey, St. Paul, Minnesota, Plate 5.

Witthuhn, M.K. and Alexander, E. C., Jr., 1995, Sinkholes and Sinkhole Probability: Geologic Atlas of Fillmore County, Minnesota, County Atlas Series C-8, Minnesota Geological Survey, St. Paul, Minnesota, Plate 8.