North Aegean Shelf
The North Aegean Shelf extends east from the east coast of the Chalkidike peninsula along the Macedonian and Thracian coasts of Greece . This Ierissos - Alexandroupoli shelf area was found in the late Pleistocene , around 14,000 or 16,000 BC. Chr. , Toward the end of the cold period, a maximum depression of the sea of about -120 meters. About 5300 square kilometers of the North Aegean shelf area lay dry and were exposed to erosion. Two larger lakes have formed in the Gulf of Ierissos and on the Strymonas , some smaller lakes are only available temporarily. The Nestos had united with the Strymonas west of Thasos and emptied into the sea on the outer Strymonas plateau. The western part of the shelf level was largely covered by sand dunes, elongated, higher sand hills at breaklines, and some swamps. On the flat Samothraki plateau there were dunes, marshes and, in addition to the more important rivers Evros and Filiouris, a number of smaller, regional rivers. The entire shelf level was dominated by the steep elevations of the Ipsarion (1204 m) in the area of Thasos and the Fengari (1624 m) in the area of Samothrace . The ice melt and the postglacial rise of the seas began.
In the early period of the ice melt, the sea level rose again by around 50 meters, finally around 13,000 BC. Chr. To reach a level of -70 meters, so about 30 percent of the formerly dry shelf were flooded. The lakes in the Gulfs of Ierissos, Strymon and Kavala had become shallower. The Gulf of Kavala and the adjoining eastern part of the Strymon Plateau were only ten meters above sea level, while the western part of the plateau was already under water. The sea penetrated deep into the land along the estuaries of the Strymon, Nestos and Filiouris rivers. The Strymonas now flowed into the Strymonikos Gulf in the northwest , and the Nestos west of Thasos directly into the Gulf. The sea reached just a few kilometers from today's southern coastline of Thasos. Thasos and Samothrace were already emerging as peninsulas.
After the first strong ice melt and the corresponding sea rise, a cold interim period occurred and the sea rise was limited to a maximum of 20 meters. The sea level was at the transition from the Pleistocene to the Holocene , around 10,500 BC. BC , at about −50 meters. During this rise, a considerable, very shallow part of the shelf was flooded, so that a great deal of land was lost to the sea. The coastline already ran along its current position in areas with steep slopes, including in the southern half of Thasos between Skala Kalirachis and Skala Potamias. The Gulf of Ierissos and the Strymonian Gulf almost reached their present shape. In the Gulf of Kavala the sea penetrated along the course of the Nestos river like a channel into the tectonic Kavala basin. A far penetration of the sea also took place on the Samothraki plateau. The island was cut off from the mainland by a sea channel.
After 10,500 BC The rapid rise in sea level began again and was around 7,500 BC. BC only 15 meters below the current position. The coastline at that time was close to what it is today. Sands and gravel brought in by the rivers flowing in; near the coast they formed massive deposits of Holocene sediments. The fine sediment input was distributed over a wide area by ocean currents and partially covered the coarse deposits of the flooded river channels and valleys. Sediments deposited by the Nestos filled its mouths and the course of the river changed from southwest to southeast. Thasos was separated from the mainland. The rapid rise in the sea slowed down from around 7500 BC. The current position of the coastline has only been reached over the last millennia.
literature
- C. Perissoratis, D. Mitropoulos: Late Quaternary Evolution of the Northern Aegean Shelf , Institute of Geology and Mineral Exploration, Athens, Greece, Quaternary Research 32, 36-50 (1989)
- C. Perissoratis, SA Moorby, C. Papavasiliou, DS Cronan, I. Angelopoulos, D. Mitropoulos, and F. Sakellariadou: Geology and geo-chemistry of the surficial Sediments off Thraki, Northern Greece , Marine Geology 75 (1987), p 209-224.
- C. Perissoratis, I. Angelopoulos and D. Mitropoulos: Exploring the offshore area of NE Greece for placer deposits: Geologie framework and preliminary results , in Marine Minerals: Resource Assessment and Strategies Reidel, Dordrecht, 1987, pp. 57-70.
- C. Perissoratis and van Andel: A late Pleistocene unconformity in a gravity core taken in the Kavalla Gulf, Northern Aegean , Marine Geology 81, 1988, pp. 53-61.
- C. Perissoratis, I. Angelopoulos, D. Matarangas and N. Konispoliatis: Bathymetry, morphology and characteristics of the surface Sediments in the area Ierissos-Alexandroupolis (preliminary results) , Panhellenic Symposium on Ocean Fisheries, 1984, pp. 437-445.