Bathymetry of the eastern Mediterranean Sea

Abstract

About 23,000 km of continuous precision echo sounding profiles supplemented by about 15,000 km of less precise profiles were compiled for the eastern Mediterranean Sea. Examination of the profiles reveals the presence of a long sinuous ridge that rises to depths shallower than 2500 m. This feature, the Mediterranean Ridge, is bounded on both sides by steep escarpments that lead down into trenches. The trenches north of the ridge, named Strabo Trench and Pliny Trench, have little fill, owing probably to insufficient supply of sediment. On the south side of the Mediterranean Ridge is the Herodotus Abyssal Plain, about 1200 km long. South of this plain is a broad gentle slope of the Nile Cone that spreads out from the Nile Delta.Thirty-two long piston cores show that the top 10 meters of the Nile Cone consists mostly of gray lutite. In and near the Herodotus Abyssal Plain at the base of the cone are many layers of sandy turbidites. Beyond the abyssal plain and covering most of the Mediterranean Ridge and the area north of it, the bottom consists of Globigerina ooze having intercalated tephra probably from the active volcano Santorini located northeast of Crete. Most cores also contain numerous sapropelic layers that indicate frequent occurrence of anaerobic conditions during the Late Pleistocene Epoch.The interpretation of the sounding profiles and sediments leads to the conclusion that the Mediterranean Ridge is tectonic in origin and that it constitutes a dam against which abut sediments contributed by the Nile River and carried seaward probably by both general diffusion and turbidity currents.