Digital Ground Penetrating Radar (GPR): A New Geophysical Tool for Coastal Barrier Research (Examples from the Atlantic, Gulf and Pacific Coasts, U.S.A.)

摘要: Although digital ground penetrating radar (GPR) is still in its infancy, results indicate that it will soon become one of the most significant geophysical instruments for coastal barrier studies. GPR can infer stratigraphic trends, and therefore directions progradation and/or aggradation, delineate sedimentary facies, determine depth to fresh-brackish water interface shallow freshwater conditions (i.e., Galveston Island). Internal structure barriers consisting sand, broken shell fragments boulder-gravel Georgia, Florida, Texas, Oregon Washington States are illustrated using GPR. Seaward dipping reflections (1-23°) from paleo-beach surfaces occur depths 12m. Severe signal loss noted on all at approximately level low tide. Gulf Coast have thin lenses (< 4 m), below which brackish attenuates electromagnetic energy. In contrast, best high wave energy tidally-influenced (3.7 m) Pacific clastic sand with dips 1-2° 12 m deep. A beach Seaside, Oregon, has good inclined 23° Shelly beaches Anastasia Island, Florida exhibit semi-continuous seaward (3-6°) 6 m.