NPS Geodiversity Atlas—Saint Croix National Scenic Riverway, Wisconsin and Minnesota

Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.

view of island in river
View toward Saint Croix Island.


Saint Croix National Scenic Riverway encompasses 406 km (252 mi) of river, including the Saint Croix River and the Namekagon River in midwestern Minnesota (Chisago, Pine, and Washington Counties) and Wisconsin (Bayfield, Burnett, Douglas, Pierce, Polk, Saint Croix, Sawyer, and Washburn Counties). When Saint Croix National Scenic Riverway was originally established on October 2, 1968, only the upper 160 km (100 mi) of the Saint Croix River and entire 160 km (100 mi) course of the Namekagon River were included. The lower 84 km (52 mi) of the Saint Croix River were added to Saint Croix National Scenic Riverway under a 1972 amendment. The riverway contains approximately 27,304 hectares (67,470 acres) of river and forested landscape, and is recognized for its scenic, geologic, recreational, cultural, and ecological resources. Prominent features at Saint Croix National Scenic Riverway include: the Saint Croix and Namekagon Rivers and their tributaries; cascading rapids and waterfalls; riparian, wetland, and broad floodplain areas flanking the waterways; and steep bedrock cliffs.

Geologic Setting

The bedrock geology of Saint Croix National Scenic Riverway predominantly consists of Paleozoic sedimentary strata including Cambrian sandstones and Ordovician carbonate rocks. The geologic history of the Saint Croix National Scenic Riverway area includes regional-scale extension associated with the Mesoproterozoic Midcontinent Rift event, the deposition of younger Paleozoic strata, and recent Pleistocene glaciation. Some of the oldest bedrock occurs in the northern area of Saint Croix National Scenic Riverway along the Saint Croix River and consists of lithic sandstones, mudstones, and conglomerates of the Mesoproterozoic Oronto and Bayfield Groups. Some of the youngest units in the park unit are Pleistocene or younger surficial deposits that include the Miller Creek, New Ulm, West Campus, Trade River, Cromwell, and Copper Falls Formations, floodplain alluvium, and colluvium.

Regional Geology

Saint Croix National Scenic River is a part of the Superior Upland Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.

Maps and Reports

The Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks. The products listed below are currently available for this park, check back often for updates as many maps, reports, and posters are still in progress.
  • Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
  • Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
  • Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
  • Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
  • Projects list basic information about the program and all products available for a park.

Source: Data Store Saved Search 3162. To search for additional information, visit the Data Store.

NPS Soil Resources Inventory project has been completed for Saint Croix National Scenic River and can be found on the NPS Data Store.

Source: Data Store Saved Search 3113. To search for additional information, visit the Data Store.

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Saint Croix National Scenic Riverway

National Park Service Geodiversity Atlas

The servicewide Geodiversity Atlas provides information on geoheritage and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.

For more information on the NPS Geodiversity Atlas, contact us.

Saint Croix National Scenic Riverway

Last updated: April 3, 2024