RESULTS OF THE GROUND PENETRATING RADAR MAPPING TECHNIQUE AT A DINOSAUR QUARRY IN BIG BEND NATIONAL PARK

Ground Penetrating Radar (GPR) was recently applied to a major dinosaur quarry in the upper Cretaceous (Maastrichtian) rocks of the Javelina Formation in Big Bend National Park, Texas. The site was chosen due to the known occurrence of large fossil bones attributed to the sauropod Alamosaurus. Alamosaurus was a titanosaurid (Dinosauria: Sauropoda) and reached adult lengths between 25-30 meters. The matrix at the quarry is a gray mudstone and the bones are encased in concretions. Although fossil bones were recovered from this site, given the articulated nature of the recovered bones, it was reasonable to hypothesize that additional bones remained in the subsurface. The GPR survey was conducted in an effort to locate additional fossil bones. The survey was conducted using a Pulse EKKO transmitter and receiver antennae pair. Anomalies detected in the subsurface were plotted on the fossil quarry map. The GPR enhanced map was then given to paleontological field teams to guide their excavation efforts. The mapped subsurface GPR anomalies were investigated; four of seven anomalies were excavated. Of the four excavated anomalies, three produced concretionary material, one a large fossil bone. GPR, as a surveying and mapping technique at this quarry with fine-grained matrix has demonstrated value. It is likely that such a survey at comparable sites will yield similar results.