GEOLOGICAL FOUNDATIONS OF ANCIENT SEAPORT ASHKELON, ISRAEL

The ancient seaport city of Ashkelon just north of Gaza on the Mediterranean coast of Israel is the site of archaeological excavations since 1985. The cultural succession at Ashkelon from Early Bronze to Middle Ages includes most notably Canaanite, Philistine, Persian, Greek, Roman, Byzantine, and Islamic-Crusader. Canaanites were the first to shape the local topography into an imposing semi-circular rampart system that encloses an area of more than 150 acres against the coast. Recent geological investigations (2008-2011) have focused on site-formation and paleoenvironmental origins of Ashkelon. Late Pleistocene-Early Holocene eolian sandstones known in the region as kurkar are exposed in the scenic cliff along the coast, standing 6 to 18 m above sea level in front of a narrow beach. High waves during a severe storm in December 2010 produced fresh exposures of kurkar and tel stratigraphy along the beach cliff. Outcroppings along the cliff and sediments recovered from probes across the tel show that kurkar underlies all archaeological deposits. Kurkar typically occurs as unconsolidated sand as close as 20 m from the shoreline. Original kurkar (pre-cultural) topography was reconstructed from the subsurface probes and total-station surveys of the beach cliff. We interpret two sub-parallel kurkar ridges, remnants of a local dune complex: one along the coast and the other about 550 m inland, both merging in the north. Waves have pushed the beach cliff back at least 20 m in the past 2500 years. Local drainage created and maintained two wadis that dissected the coastal ridge. Erosion from storms/tsunami may have breached lower standing kurkar where the wadis formed. Paleosols known in the region as hamra are found in association with kurkar. Red and yellow paleosols developed upon weathered kurkar and are more thickly and laterally developed along the coast south of the tel where kurkar rarely stands higher than about 2 m above sealevel. A very thick deposit (8.5+m) of dark yellowish brown sandy clay loam was discovered in a limited area between the kurkar ridges within the tel. The original kurkar topography clearly influenced the position of the rampart system. The distribution of artifacts from excavation records and probes shows the timing of tel growth from original topography, illustrated and animated with GIS tools.