GEO-ARCHAEOLOGY OF THE ANCIENT THEODOSIUS HARBOUR (YENIKAPI-ISTANBUL): IMPLICATIONS TO HOLOCENE SEA LEVEL AND COASTAL CHANGES

The city of Istanbul is located at the Strait of Istanbul (Bosporus), where two continents (Asia and Europe) and two marine basins (Black Sea and Mediterranean) meet. Besides from this geographical uniqueness, it is exceptional historically, by being a capital almost sixteen centuries and has been an important crossroad in the earlier history of civilization. During the preliminary construction works of a large scale Marmaray Tube Tunnel Project in due to build a tube tunnel under the sea between Asian and European parts of the city, an ancient Byzantium Harbor (Theodosius H. 4^th century) was brought out at Yenikapý within the "historical peninsula". Geological and archaeological evidences in the sedimentary sequence exposed to daylight at the excavation site have revealed significant new data enabling for the first time to correlate the Holocene sea level change, paleoenvironmental changes and the cultural sequence of the region. Archaeological evidence indicating the settlement of the Neolithic culture is particularly important in considering the contact zone between the Near Eastern Anatolia and southeast Europe.

Sedimentary sequence, with a thickness of about 7 m, consists of lower marine and upper fluvial-deltaic units above the basement. Between the base of the marine units and Miocene aged basement, gravels, cobbles and boulders mostly well rounded and include burrows were found at – 6 m together with numerous anthropogenic features. The archaeological evidence recovered amongst these cobbles includes various artefacts and human burials related to the Neolithic Fikirtepe culture that prevailed in the area at 8.4-7.3 ky BP. The marine invasion in the area started at about 6 ky BP, drowning the Lykos stream and forming an inlet. Coastal progradation started to be effective at ~3 ky BP. The marine units consist of sand sized sediments with shells and represent the characteristics of a coastal-shallow water environment. The harbour remnants, including sunken ships dates back to Byzantium time are found within this unit. Upper fluvial-deltaic sediments are represented by coarse grained and alternating graded/non-graded sediments and were deposited from the detritus of the Lykos Stream. They also include human artefacts, broken and rounded ceramic pieces, ranging from 11^th to 8^th centuries.