GEOSPATIAL AND GEOPHYSICAL SURVEY OF COASTAL DEFENSES AT FORT CASWELL, NORTH CAROLINA

Fort Caswell, located on the Cape Fear Inlet end of Oak Island, served from the 1830's to the 1940's as a part of the coastal defenses for the port of Wilmington, North Carolina. The recent excavations at Fort Caswell have revealed that the civil war fort is rich in architectural remains from the brick and stone defenses. The continuing excavations seek to understand the extent and survival of the subsurface features. Survey on the site focuses on complementing this research interest. Elevation survey with Real Time Kinematic GPS provided data to build digital elevation models (DEM) of surface topography. Satellite imagery was used to analyze vegetation health through the use of band ratios to emphasize local contrast in vegetation health. The satellite imagery analysis revealed potential features across the entire site. Aground penetrating radar (GPR) survey in May 2015 worked to locate building foundations, wall remains, and a brick lined cistern in the subsurface. Results from the GPR survey and the derived DEM provided detailed mapping of features around the inner citadel, fort walls, and lined moat. These surveys were combined to locate and identify features in the subsurface. A comprehensive map of the site will combine the excavation data and survey data to extrapolate the conditions across the Fort Caswell site.