This webpage covers geologic data and maps for Minnesota that are generally 1:100,000 to 1:200,000 in scale and that are smaller than the state in extent.
The County Geologic Atlases and Regional Hydrogeologic Assessments are available for a number of counties. They are interrelated so are described together.
County Geologic Atlas: A systematic study of a county's geologic and ground water resources. Geologic studies include both near-surface deposits and bedrock. Ground water studies include flow systems, aquifer capacity, ground water chemistry, and sensitivity of the ground water to pollution. In some areas sand and gravel deposits, sinkholes, or other features are studied. The atlases are generally 1:100,000-scale.
Regional Hydrogeologic Assessment: This is similar to a County Geologic Atlas in that both geology and ground water are studied. However, an assessment covers a larger area, typically four to nine counties, in less detail. It emphasizes near-surface geologic, ground water, and pollution sensitivity mapping. The assessments are generally 1:200,000-scale.
Most atlas and assessment projects are done in two parts which are published and distributed as two separate products:
- Part A, compiled by the Minnesota Geological Survey, covers basic bedrock and surficial geology and creates databases of information such as wells and soil borings. Part A is completed about two years before Part B.
- Part B, compiled by the Minnesota Department of Natural Resources, covers hydrogeology and ground water sensitivity. Information compiled in Part A is used to create Part B.
Information on the location and the quality of aggregate resources (sand, gravel and crushed stone).
Karst is an efficiently drained landscape that forms on soluble rock, typified by caves, sinkholes and other landforms. It is mainly, but not exclusively, formed on limestone. In Minnesota, karst is generally found in the southeastern area and in Pine County.
Karst data is often included in County Geologic Atlases and Regional Hydrogeologic Assessments (covered above); however, the following websites focus on karst.
Twin Cities Metro
Anoka, Carver, Dakota, Hennepin, Ramsey, Scott and Washington counties