GEOLOGIC MAP OF THE WEST-CENTRAL BUFFALO NATIONAL RIVER REGION, NORTHERN ARKANSAS

This map presents a compilation of both previously published and unpublished U.S. Geological Survey geologic mapping for all or parts of eight 1:24,000-scale quadrangles in the west-central Buffalo National River area, and makes available a supporting seamless Geographic Information System (GIS) database. The map includes updates to previous data, with most changes made within areas of the earliest published Jasper, Ponca, and Hasty quadrangles. Changes to previous maps were based on both additional field observations and interpretations of high-resolution topographic data from LiDAR (Light Detection and Ranging) surveys available for the western map area. Added unit polygons reflect (1) a consistent subdivision of the middle Ordovician Everton Formation into upper and lower parts, (2) identification of Pennsylvanian Atoka Formation on highest ridges of the Jasper Quadrangle to match its distribution on the Ponca and the nearby Boxley quadrangles, and (3) widespread recognition of a series of Quaternary terrace deposits that mark older, higher positions of the Buffalo River. In the context of new LiDAR topographic data, contacts for ledge-forming upper Mississippian and Pennsylvanian units were inspected between field traverses and modified, where needed, to match their typical topographic expression. The compilation include over 2200 field-control elevation points on upper and lower contacts of the Boone Formation that were used to construct structure contours for this marker unit to illustrate the location and effect of numerous faults and folds across the area. Geologic data from the compilation give information on a variety of geological topics, including: (1) progressive truncations of units below two regional unconformities at the base of Mississippian and Pennsylvanian sequences, (2) the style of late Paleozoic faulting and folding, (3) the Quaternary record of landscape development during Buffalo River valley incision, and (4) the bedrock controls on abundant karst features (e.g., caves, sinkholes, springs).