Excavations in the Helike Delta on the Gulf of Corinth have brought to light architectural remains from the Early Bronze Age (EBA), Geometric, Classical, Hellenistic, Roman, and Byzantine periods. Borehole results suggest that a lagoon intermittently occupied much of the delta during the Holocene. We discovered a well-preserved EBA settlement about 1km inland from the present shore, buried under 3 to 5m of fine sediments containing marine, brackish, and freshwater microfossils. A Classical site 130m away, buried under 3m of similar sediments, may have been destroyed by the earthquake and tsunami of 373 B.C., which submerged the city of Helike. Possible tsunami evidence is noted. Although the EBA and Classical sites were both long submerged and buried by lagoonal sediments, tectonic uplift has raised both horizons above sea level. A shallow black clay layer suggests that a marsh covered the Classical and EBA sites in Byzantine times. © 2011 Wiley Periodicals, Inc.