The geological evolution of the Black Sea (2)
  When the ice began to melt in the late Mindel (Elsterian) Glaciation (some 400,000-500,000 year ago), the Chaudian Sea-Lake became filled with melt waters and turned into the Paleoeuxinian basin. Its outline resembled the modern Black Sea and the Azov Sea. In the north-east it was connected to the Caspian Sea through the Kumo-Manych depression, and in the south-west to the Sea of Marmara through the Bosphorus. At the time, the Sea of Marmara was isolated from the Mediterranean and was also greatly affected by reduced salinity. The fauna of the Paleoeuxinian basin was of a Pontian type.
  The Riss-Würm Interglacial Period (100,000-150,000 years ago) heralded a new phase in the history of the Black Sea. Following the opening of the Dardanelles for the first time since the formation of the Tethys Sea, the future Black Sea became connected to the Mediterranean and the world ocean. The so-called Karangat Basin or Karangat Sea was formed, with a salinity higher than that of the modern Black Sea. Various representatives of marine flora and fauna were introduced into it together with ocean waters. They occupied a larger part of the basin, forcing the brackish water and Pontian species into bays, limans and river estuaries with reduced salinities. However, that basin too was to undergo changes.
  Some 18,000-20,000 years ago the Karangat Sea was replaced by the Neoeuxinian Lake-Sea. This coincided with the end of the last W?rm Glaciation. The sea was filled with melting waters. Once again it lost its connection to the ocean and its salinity was greatly reduced. The halophilic oceanic flora and fauna also disappeared; while the Pontian species that had survived the difficult Karangat period in limans and river estuaries came out of hiding and yet again occupied the entire sea.
  After approximately 10,000 years the basin entered its current phase and the modern Black Sea was formed. In fact, the word "modern" in this case does not mean that the sea was identical to what it is today. In the beginning, about 7,000 years ago, (although some experts believe that it was even later, about 5,000 years ago) a connection to the Mediterranean and the world ocean was established through the Bosphorus and the Dardanelles. A gradual salinisation of the Black Sea followed and it is believed that within 1,000-1,500 years the salinity of the sea became sufficient to support a large number of Mediterranean species. Today about 80 percent of the Black Sea fauna are Mediterranean settlers ("Mediterranean immigrants"). The Pontian relics have again moved to the bays and limans with low salinities, as happened during the time of the Karangat basin.
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