OFR16-4, Preliminary geologic maps of Lake and St. Louis Counties, northeastern Minnesota

Abstract

This Open-File Report (OFR) is a repository for on-going mapping in Lake and St. Louis counties that began in 2015 and will be largely completed by 2020. It contains preliminary bedrock and surficial geologic maps and associated products covering parts, and eventually all of the two counties. Because the counties are large, they have been divided for mapping purposes into subareas, each containing the name Arrowhead. Surficial, Bedrock Topography, and Depth to Bedrock maps are divided into 4 subareas referred to here as the Central (content prefixed “CA,” 2016, 2017); Southeastern (SeA, 2017, 2018); Southwestern (SwA, 2018), and Northern Arrowhead (NA) areas. Bedrock maps and associated files cover 3 subareas referred to as Central (CA, 2016); Southern (SA, 2017); and Northern Arrowhead (NA, 2018). Note that the boundaries of subareas differ somewhat between the surficial and bedrock maps. Products within this Open File Report include bedrock geologic maps, surficial geologic maps, bedrock topography and depth to bedrock maps, Quaternary stratigraphy, sand distribution models, corresponding GIS files, and other digital content. Ancillary files such as technical reports, geophysical imagery and models, and geochronologic data are included for bedrock mapping in the 3 bedrock subareas. Once these preliminary products are complete, the data and interpretations will be recombined into County Geologic Atlases that will supersede this OFR. Authors of individual maps and reports within the OFR include: Boerboom, T.J., Chandler, V.W., Dengler, E.L., Hamilton, J.D., Horton, J.M., Jirsa, M.A., Lively, R.S., Meyer, G.N., Peterson, D.M., Radakovich, A.L., Schmitz, M.D., Setterholm, D.R., Wagner, K.G., and Wall, C.