Abstract

The coastal strand plain at Cape Henry, Virginia exhibits beach ridges and eolian dunes that have evolved in the late Holocene (<4000 years) in response to minor climate and associated sea-level fluctuations. Understanding the geomorphic response to such fluctuations is key to predicting coastal response to expected global warming. The purpose of this project is to perform a reconnaissance study to see if Ground Penetrating Radar (GPR) will adequately reveal internal structures within the geomorphic features at Cape Henry to reveal the complex sequence of events that shaped this region. For this project, we developed a GPR sampling strategy to collect data on representative geomorphic features throughout Cape Henry. At each locality this involved calibrating the GPR and performing topographic surveys. The data were processed to incorporate topographic features on the originally flat GPR profiles and processing parameters were varied to produce optimal data quality. Geological analysis indicates that dunes are not composed of simple foreset strata. Some profiles have patterns that reveal sea-ward progradation of beach ridge features. Where higher-resolution (200 MHz) data were taken, resolution was not optimal because transmitter voltage was too high; this indicates that a lower voltage transmitter be used in future work, which will also enhance quality of lower-resolution data in clean sandy conditions. Surveying GPR transects to actual elevation above mean sea level will also aid in data interpretation.