Preliminary surficial geologic map of the west half of The Ramshorn 30' x 60' quadrangle, Fremont and Park counties, Wyoming

The Ramshorn 30' x 60' quadrangle is in Fremont, Park, and Hot Springs counties, Wyoming. The quadrangle encompasses the southern Absaroka Range, northwestern Wind River Basin, and northwestern Wind River Range. This study mapped the surficial geology of the west half of The Ramshorn quadrangle at a scale of 1:100,000 in an effort to better understand the region’s geologic hazards and Quaternary geology. ¶This work is part of a broader effort by the Wyoming State Geological Survey to map the surficial geology of Wyoming at 1:100,000 scale. In particular, surficial geologic mapping on The Ramshorn quadrangle is motivated by a need for updated landslide mapping in one of the most landslide-prone regions of the state. Landslides have historically impacted U.S. Highway 26/287, an important transportation corridor in the southwest quadrant of the map, yet the only prior landslide inventories in the area were completed 20 years ago without field verification and before the availability of lidar data. This mapping leverages recently released lidar data for Fremont County along with select ground truthing to characterize the distribution of landslides and other surficial deposits in the study area. In the process, this work provides additional insights into the recent geologic history of the region through the mapping and documentation of Quaternary glacial and alluvial deposits. The data presented here are intended to improve geologic hazard assessments and to help land managers, local governments, and the public make informed land-use decisions in this dynamic landscape.