NEW GEOLOGIC MAP OF BEARS EARS NATIONAL MONUMENT

Bears Ears National Monument (BENM) covers 1.4 million acres across the Colorado Plateau in southeastern Utah. BENM was created in 2016 to protect a myriad of natural resources including thousands of cultural and archeological sites, geologic features, fossils, and scenic wilderness. The landscape varies from deep canyons with countless tributaries to mesas bordered by towers and buttes, to alpine peaks over 11,000 feet high. A unique section of Upper Pennsylvanian to Upper Cretaceous sedimentary rocks record deposition in ancient inland seas, tidal flats, sabkhas, alluvial plains, and dune-covered deserts dotted with oases. Intrusion of igneous laccoliths, dikes, and sills of the Abajo Mountains accompanied regional Paleogene uplift of the rigid Colorado Plateau. Regional faulting created the massive Monument Upwarp, a monocline that sprawls across most of BENM. The current landscape of spectacular canyons, mesas, and towers is the result of significant exhumation driven in part by the capture of the ancestral upper Colorado, San Juan, and Green Rivers by the lower Colorado River ~5.5 Ma.

We present a first of its kind new geologic map of BENM. This map is a compilation of nearly three dozen maps of different vintages, sizes, and scales, combined with reconciled border match issues and regional stratigraphic and nomenclature discrepancies. Several areas had no previous mapping and required new field and computer mapping. The map was split into smaller sections to address cartographic issues and for publication in Geology of Utah’s Parks and Monuments, Utah Geological Association Publication 28, 4^th edition. Intermediate-scale, large-area maps like these are important because they integrate map data of different vintages, sizes, and scales; standardize stratigraphy; update outdated nomenclature and geologic concepts; and create new GIS data of older publications. This map provides a strong foundation for future geologic mapping projects to produce regional, seamless geologic maps and detailed maps of specific areas.