GEOLOGY OF THE DURHAM QUADRANGLE, MADISON AND WASHINGTON COUNTIES, ARKANSAS

This map graphically depicts the bedrock and surficial geology of the Durham 7.5-minute quadrangle. In this area approximately 1300 feet (396 meters) of Mississippian (Osagean) to Pennsylvanian (Atokan) carbonate and clastic rocks are exposed. The area lies within the Interior Highlands Region and is situated on the Boston Mountains Plateau which has developed on the southwest flank of the Ozark Dome in northwest Arkansas.

Recent mapping has delineated previously unmapped stratigraphic units and improved resolution of the bedrock geology and structural features. For instance, greater control on the location of the northeast-trending Drakes Creek Fault, its accessory faults, and accompanying drag fold was achieved. The Drakes Creek, along with the Hammond Mountain Fault, are the two named structural features delineated on the map. The Drakes Creek Fault is one of the major basement faults in northwest Arkansas. It strikes northeast and can be traced at the surface for at least 45 miles (72 kilometers). On the Durham quadrangle, it runs for more than 10 miles from the southwestern margin to the northeast corner. It is a normal fault downthrown to the southeast approximately 160 - 400 feet (48 - 122meters). The footwall units are downwarped steeply toward the fault, proximal to the fault trace. The Hammond Mountain Fault, located near the southwest corner of the map, is a normal fault downthrown approximately 40 feet (12 meters) to the south.

The White River is the major drainage in this area and flows from the southeast corner to the northwest corner of this quadrangle. The White River has three distinct terrace levels represented on the map. These terraces demarcate past levels of the White River’s channel and floodplain as it eroded the bedrock. Newly discovered strath terraces approximately 80 to 100 feet (24 to 30 meters) above the current channel may lead to greater insight of landscape evolution in upland fluvial systems in the Ozark Plateaus Region.

Also, mapping of recent landslides on the Durham quadrangle has provided important data to assess potential risks to development in these areas.