The morphometry of the Black Sea (5)
	The centre of the Black Sea depression consists of a deep water basin with a depth of 2,000-2,200 m. The maximum depth is 2,212 m. The bottom of the basin is an aggraded plain formed by diverse formations, which vary both in terms of their age and their geological structure. Most of the Black Sea depressions are located within the boundaries of the Alpine geosynclinal area.
	Many scientists believe that the formation of the Black Sea depression is linked to the process of oceanisation of both the continental crust and a relict natural depression, which is represented by a residual basin of the ancient Tethys Sea. The general outlines of the modern depression were already formed in the Oligocene, which was when the folded structures which gradually separated the depression from the Tethys Sea first appeared in Asia. In the Miocene the Black Sea was part of a system of seas - the lakes of the Sarmatic basin. After a short period during which it was connected to the Mediterranean Sea, the low-salinity Pontian Lake came into existence in the Meotian Age.
	Twice during the mid-Pleistocene, the Black Sea was connected to the Mediterranean Sea, and its waters became highly saline. The low-salinity Neoeuxinic Sea was formed during the last Quaternary glaciation. Some 6,000-7,000 years ago it gained access to the Mediterranean Sea and its water acquired a higher salinity.
	Coarse detrital deposits, including pebbles, gravel and sand, dominate the coastal zone. Further from the shore they are quickly replaced by fine silt. Shell limestone is widespread in the north-western part of the sea.
	Pelitic muds are characteristic of the slope and the seafloor. Their carbonate content increases away from the shoreline, in some places exceeding 50 percent. At depths of up to 2,000 m in the south-east of the sea there are sediments composed of aleurolite and sands carried by turbidity currents.
	River run-off means that water levels in the Black Sea are higher than in the Sea of Marmara . The average salinity of the open Black Sea is 17-18 ‰ at the surface and 22-24 ‰ at a depth of 2,000 m.
	<Previous>
	Home Page | About | Data Directory | Metadata Directory Satellite Images | Red Data Book | Related Sites
	[email protected]