OF-23-07 Digital Geologic Map of the Wet Mountains Area and Associated Geochemical Data, Custer, Fremont and Huerfano Counties, Colorado

The purpose of this geologic map compilation is to provide a consistent, digital, 1:50,000-scale geologic framework for the Wet Mountains area that supports Earth MRI objectives related to critical mineral assessment and subsurface characterization. Previous geologic mapping in the area was completed over several decades at varying scales and using differing stratigraphic and structural interpretations, resulting in inconsistencies across map boundaries and data gaps in key areas.

This project compiles and standardizes existing geologic mapping, incorporates unpublished data and new field observations, and attempts to resolve discrepancies among source datasets to produce a single, internally consistent geologic map. Generalization of selected features was applied where necessary to meet scale requirements while preserving geologically meaningful relationships.

The compiled geologic framework is intended to facilitate integration with high-resolution geophysical data, support geochemical sampling and mineral resource evaluations, and provide a reliable spatial foundation for future geologic, mineral resource, and land management investigations in the Wet Mountains region. Contributors to this mapping project include Colorado Geological Survey geologists as well as members of the Colorado School of Mines Geology Department, with work performed from 2023 to 2026. Digital ZIP download. OF-23-07.

***Note on source maps used in this compilation:

Due to file size restrictions, please contact the CGS directly at askcgs@coloradogeologicalsurvey.org for source map GIS files.

From the abstract:

This digital geologic map compilation presents a 1:50,000-scale geologic framework for the Wet Mountains area of south-central Colorado, developed as part of the U.S. Geological Survey Earth Mapping Resources Initiative (Earth MRI). The map integrates geologic information compiled from published sources, unpublished data, and new field mapping conducted by the Colorado Geological Survey. Source geologic maps and supporting data were digitized and harmonized into a GeMS-compliant geodatabase. Compilation involved reconciliation of geologic unit nomenclature, contacts, structures, and stratigraphic relationships across map boundaries, and attempts to resolve discrepancies among source datasets through comparison and targeted field verification in areas of conflicting or incomplete coverage. Portions of the map were generalized to meet the 1:50,000 scale requirement. References for compiled geologic information are provided within the GIS datasets, and digitized versions of key source geologic maps used in the compilation are included as part of the data release (by request).