THE NEW GEOLOGICAL MAP OF MINNESOTA

The new geological map of Minnesota is a 2-resolution, layered set of databases that includes the offshore, that underlies bathymetric and soil mapping, and that is as compatible as possible with neighbors. The geological mapping database is underpinned by authored and peer-reviewed geological maps, while efforts to refine stratigraphic nomenclature are ongoing. Progressively more seamless geological polygons, at 1:500,000 and 1:100,000, are tending to have thickness indicated, while properties, heterogeneity, and uncertainty will gradually be more specified. Parsing of legends, to facilitate queries, is using broadly accepted, well-defined terminology, to facilitate inference of properties. A layered 1:500,000 state bedrock geologic map is largely complete, while a new state surficial geology map is in development. New 1:100,000 mapping is county-based, is meant to be complete statewide within a decade or two, and is focused on societal needs, with an emphasis on groundwater protection and management, while taking a broad approach. Where required to resolve issues, 1:24,000 mapping is conducted. The geological mapping is meant to be linked to the following associated spatial databases. The publication database, which is spatial through publication footprints, includes nearly 50,000 pages, and 700 scanned maps, both searchable. Geological databases include field observations, geotechnical data, hydrogeological data, images, karst database, the mineral exploration document archive maintained by the natural resources department (DNR), sediment texture and lithology, as well as the largest and most important database in this group – the half-million site water well database. Geological collection databases include cuttings, the million-meter DNR drill core library, fossils at the Bell Museum, geochemical samples, hand samples, sediment samples, and thin sections. Geophysical databases include borehole geophysics, gravity, magnetic, rock properties, and soundings; statewide geochemical databases include groundwater, soil, and soil parent material; while geochronological databases are in varying states. Many elements of this new ‘map’ exist, some are in preparation, and some are aspirational. The map will never be finished, but rather will be regularly-updated.