The application of ground-penetrating radar to a coastal prehistoric archaeological site, Cape Henlopen, Delaware, USA

Abstract

Cape Henlopen, Delaware is a coastal spit complex located at the confluence of Delaware Bay and the Atlantic Ocean. This region was occupied by prehistoric peoples throughout the evolution of ancestral Cape Henlopen. A ground-penetrating radar (GPR) survey was conducted at one of the prehistoric archaeological sites (7S-D-30B) located within the Cape Henlopen Archaeological District. The site was in a remote location in the center of a tide dominated back-barrier marsh. Ground-penetrating radar waves penetrated to depths of 7 m, and four major sets of reflections were observed. Three sets were interpreted to be GPR images of geomorphic units associated with the spit complex, and the fourth was identified as the GPR image of a shell midden deposit. The GPR survey was used to determine the approximate dimensions of the shell midden, including its depth below ground surface (up to 2.1 m) and horzontal extent (∼250 m2), and to establish the paleoenvironmental setting and antecedent topography of the site prior to occupation. The GPR data suggests that the shell midden was initially deposited upon an aeolian dune surface and the antecedent topography at the site included an up to 1 m deep trough located 5 m to the north of, and trending parallel to, the axis of a present-day topographic high. This survey illustrates that GPR is a useful, noninvasive, tool that may be implemented at archaeological sites in coastal areas. It provides constraints on the environmental setting and topography of the terrain which prehistoric peoples inhabited, and it can be used in planning excavations at sites in coastal geomorphic settings. © 2000 John Wiley & Sons, Inc.