Marine Geophysical and Geomorphic Survey of Submerged Bronze Age Shorelines and Anchorage SItes at Kalamianos (Korphos, Greece)

Abstract

<p>The modern coastline provides few clues as to the ancient harbour configuration since Kalamianos has been partially submerged by > 6 m of relative sea-level rise since the Early Helladic. In 2009, a detailed marine geophysical survey and underwater diver search was conducted in the inshore waters to identify potential anchorage sites and to examine evidence for coastal subsidence. Single-beam bathymetry and magnetic gradiometer data were acquired and integrated within a detailed digital bathymetric model (DBM).</p> <p>The DBM revealed two submerged beachrock platforms (BR-1, BR-2) paralleling the modern shoreline and a submerged isthmus connecting the mainland with small island 200 m offshore. The BR-1 platform (3.5-3.7 m depth) contained abundant Late Helladic (LH; 1300-1190 BC) pottery sherds (30-50%) and wood charcoal fragments.¹⁴C dating of the extracted charcoal yielded an AMS ¹⁴C uncalibrated age of 3250±40 BP, consistent with the LH ceramics. The BR-2 platform (5.8-5.9 m depth) contained less pottery (<20%) and included well-preserved fragments of Early Helladic (EH) jars.</p> <p>The beachrock elevations and ¹⁴C and pottery ages were used to reconstruct a sea level curve and a series of paleogeographic maps of the EH to LH shorelines. The presence of abundant pottery and wood charcoal in the BR-1 beachrock indicates that shipping activity during the LH was focused at the south end of the site in a western harbour basin. This is supported by magnetic gradiometer results, which identified several magnetic anomalies in the western harbour basin. These were investigated by diver search and found to be concentrations of ship ballast stones (mainly andesite) and clay pottery.</p>