GEOMORPHOLOGICAL AND ARCHAEOLOGICAL STUDY OF THE BROADER AREA OF THE MYCENAEAN DAM OF MEGALO REMA AND ANCIENT TIRYNS, SOUTHEASTERN ARGIVE PLAIN, PELOPONNESUS

Résumé

Along the eastern margins of the Argive plain, in the torrent of Mégalo Rema and at a distance of 4 kilometers east of ancient Tiryns, lies the "Mycenaean dam of ancient Tiryns" a unique technological work of 13th century B.C. It is believed that it was constructed for the effective protection of the immediate environs of the Mycenaean acropolis of Tiryns from the great floods of Mégalo Rema torrent which was flowing just south of the citadel in Mycenaean times. This technical feat is survived in very good condition, having an almost N-S direction, a length of 80-100 meters, a base of 10 meters and an extant height of 8 meters. Its external side is lined with Cyclopean walls. The stability of the dam is strengthened by the presence of flysch on its southern end. The diversion of the channel of Mégalo Rema was accomplished by the digging of a 1.4 Km long artificial channel having a SSW direction and joining downstream with the natural channel of Agios Adrianos Rema which discharges in the Gulf of Argos farther south from ancient Tiryns. The course of this downstream part of the new Mégalo Rema was again diverted by the Venetians around 1500 A.D. The presence of this dam comprises a fundamental reference point for the geomorphological evolution of this area in the last 3200 years, given that when it was constructed the drainage network of Mégalo Rema had already incised in the Pleistocene sediments to a depth of about 10 meters as testified by its inactive channel behind the dam. The ensuing downcutting in the artificial channel during the last 3200 years is 2 meters below the depth of the inactive channel. The incision processes in this time period were not continuous resulting in the formation of a 3-4 meter inner alluvial terrace probably in post - Roman times. The construction of the Mycenaean dam for flood protective purposes seems to be valid, but the study of the evolution of the broader coastal environment of the Tiryns acropolis leads to an equally important hypothesis that the high sedimentation rates of Mégalo Rema had been creating serious problems in the sediment filling of this Mycenaean port whose operation was vitally important for the broader area of the Mycenaean Argive plain.