Impact of evaporite dissolution and collapse on highways, and other cultural features in the Texas Panhandle and eastern New Mexico
Geological investigations in the Texas Panhandle and eastern New Mexico indicate that regional subsurface dissolution of Permian evaporites has occurred and is an ongoing process. Evidence of removal of large volumes of evaporites (mainly halite) and collapse of overlying beds is demonstrated by cross sections constructed from gamma-ray logs. Surface manifestation of subsurface dissolution and collapse is clearly shown in Hall County, Texas, where over 400 sinkholes and undrained depressions have been identified from aerial photographs. Sinkhole diameters up to approximately 100 m (300 ft) and depths to 15 m (50 ft) have been observed. Eleven active northeast- and southwest-trending fractures and faults have been recognized, some of which are demonstrated as patched sections of highways. Formation of collapse features and faults that damage highways is a recognized problem in the region. Stock tanks and large reservoirs are also affected to a lesser degree. Dissolution and collapse pose difficult problems for geologists, highway engineers, and maintenance crews. Areas of active subsurface dissolution have been identified, but development of collapse features and faults at the surface generally follows no predictable pattern. The history of, and potential for, evaporite dissolution should be investigated in each area before construction of highways, reservoirs, and stock tanks. Areas with high densities of collapse features, fractures, and faults should be avoided when possible.