LOCATING ARCHAEOLOGICAL HORIZONS WITH C-14 SEDIMENT DATING - THE CASEOF THE LOST CITY OF HELIKE

In 373 sc a catastrophic earthquake and seismic sea wave destroyed Hel ike, a Greek city near Aigion on the southern shore of the Gulf of cor inth. The ruins were buried by sediments of unknown depth, leaving no trace of the city. We here discuss the radiocarbon dating of organic s ediment samples recovered from seven boreholes drilled on the coastal plain in the area where ancient sources located Helike. Most of the sa mples apparently acquired a substantial addition of older carbon from natural sources, and hence their apparent ages are older than the true ages of sedimentation. However, if we assume that the addition is sys tematic, we can use the apparent ages to show that the sedimentation r ate was initially rapid (about 1 cm yr(-1)) for the strata between 40 and 10 m below the surface, and then decreased by an order of magnitud e about 6500 yr ago. A related change in the sediment deposition at ab out the same time has been found in many other marine deltas throughou t the world, probably due to the deceleration of the global sea-level rise. we conclude that in the boreholes sampled by the present data, t he horizon corresponding to ancient Helike is less than 8 m deep.