SCALE DIFFERENTIATION OF CHANNEL-SHAPED GEORADAR ANOMALIES IN MIXED CLASTIC (BLACK SEA, UKRAINE) AND CARBONATE (THE BAHAMAS) BARRIER LITHOSOMES: GEOARCHAEOLOGICAL IMPLICATIONS

Shore-parallel ground-penetrating radar (800 MHz GPR) profiles along the baymouth barriers of the northwest Black Sea coast (Ukraine) and the Sugarloaf area of San Salvador Island (the Bahamas) reveal a suite of concave-up subsurface anomalies in regions of long-term cultural occupation. In 2D radargrams, there are several scales of channel-like features, ranging from width/depth dimensions of ~1.5/0.3 m to ~10/2 m. The former are consistent with dimensions of shallow graves. Along the Black Sea coast, a number of altars and burials spanning >2,000 years may be preserved in regions of net progradation. The San Salvador geophysical profile is adjacent to the Three Dog Site (SS21) and subsurface signatures are similar to those at historical cemeteries on nearby Eleuthera Island, including the Hatchet Bay Site, Alice Town (EL-5) and Cove Cemetery Site, Green Castle (EL-8). The larger structures correspond to shallow channels and swales that serve as an archive of past geological processes (overwash, breaching, and paleo-wetlands). The internal reflection patterns range from high-amplitude diffraction patterns (vegetation, skeletal remains, bioturbation structures) to a variety of channel-fill types (conformable, mounded, complex). In some instances, shore-normal surveys may be required to ascertain the continuity of a subsurface feature. Such additional data helps to visualize the morphology of buried features, improve calculations of true dip angles, and ultimately aids in distinguishing very shallow swales or channels (potentially used for navigation and fishing) from more equidimensional excavations (burial pits, sea turtle nests, etc.). Along with diagnostic GPR signatures of coastal landforms (beach ridges, dunes, scarps) and cultural features (mound-shaped middens), our findings provide a more complete paleogeographic context for sites of past human habitation from late Holocene to historical times.