The formation of the Black sea
Black sea, the Pontos euxeinos (hospitable) of the ancient Greeks, Kara Dengiz Turks, mavri Thalassa in modern Greek, is surrounded by land on almost all sides and communicates with the Mediterranean sea only through narrow and like a river Strait of the Thracian Bosphorus. Speaking generally, it represents a very correct and deep pool with a very simple bottom topography. Everywhere to its shores and adjacent narrow coastal strip of shallow sea depth is less than one hundred fathoms. The line is one hundred suzannah depths comes very close to the shores of the Crimea, the Caucasus and Asia minor and moves away from the coast at a greater distance only to the North-West corner of the Black sea, in the space of Sevastopol – Odessa – Varna and near the Kerch Strait.
After depths of about a hundred fathoms, the sea floor begins to drop and cool and soon comes to the depth of 800 fathoms; then there is already a basic, huge and flat area of the sea with depths of about one thousand fathoms. Greatest, is still known, the depth of the Black sea in 1227 fathoms have almost the intersection of the Sevastopol Meridian with the parallel of Sukhum.
The greatest length of the Black sea in the direction from East to West is 1160 kilometers (url); the biggest stretch from North to South – 600 km; the narrowest place between the Crimea and lying to the South of Anatolia (Turkish coast) is 270 km away.
The black sea is itself a surface of about 411540 quadras. km and at an average depth of approximately 654 yards (1197 m.), comprises, according to Spindler, 492565 cubic km of water.
The water of the Black sea, especially in surface layers, much less salty than seawater. On average for every thousand grams of the black sea water is 18 grams of salt, at the same time, as in the Atlantic ocean at a thousand g. of water have salt – 35 grams, and even in the Red sea almost 39 grams.
At the North-Western shores of the Black sea, in the area covered by waters of the Dnieper, Danube and other rivers, the salinity of the Black sea is even less significant and even at a considerable distance from the shore down to 13 grams.
With depth the salinity of the Black sea increases, slowly at first, to a depth of 30 fathoms. and then faster – to a depth of 50 fathoms.; further, the saltiness also increases, but slower. At depths of 200 fathoms or more. salinity does not change much, reaching on average 22-a-half grams. Off the coast the salinity is generally less than in the open sea.
As to the temperature of the surface layers of the Black sea, in different locations and in different months it varies very considerably, and the difference of average monthly temperatures for some items (as, for example, the coast near Odessa) gets to 20 degrees too.
In the table below we see that on all the Russian shores of the Black sea, Kerch and in addition to Batum, the most cold months on the surface of the sea are January and February, and everywhere, in addition to Batum, the water temperature goes down to an average of 5° with fractions and below. The highest temperature is observed in August (new style), reaching in average up to 22° – 23°, and under the Batum – to 26° Celsius.
Since the water of the Black sea with a salinity of 18 grams can freeze only when cooled to nearly one degree below zero, according to the above average water temperatures of the Black sea, it doesn’t freeze. For a short time covered with ice only the North-West corner of the sea near Odessa. In a very severe winter, in January 1911 in ice two feet thick, however, for a short time covered the entire area from Odessa to Cape Tarkhankut and the island Fidonisi. In Herodotus there is evidence that in the 5th century BC ice covered bluff from Chersonesos to Pantikapei, and Byzantine chroniclers report the freezing of Pontus in 401 762 G. and A. D. 762, In ice, after opening the Pont, blocked the Hellespont.
The distribution by depths, the annual course of temperature in them is still unknown, except for the immediate vicinity of Sevastopol. In General, there is no doubt that a hundred fathoms below the annual fluctuation of temperature is almost not covered.
At Sevastopol, on the depth 37 fathoms, the whole layer of water cools in winter, in February, to about 6°; the surface layers are cooled even more. Then, in may, the upper layers are heated to 17°, whereas the layers lying at a depth of 20 fathoms. reach the same temperature only in October, the same layers of the water about 30 fathoms. depth in October, despite the heat during the summer, heat only up to 8°, in order to fall again in winter to 6°.
Also in General happens in the whole Black sea. So, for the summer months, according to glubokovodnoi expedition of 1890-91 G. “the water temperature in the Black sea decreases rapidly from the surface to some depth, fathoms lying at 25 to 50 below the surface of the sea. From this layer the lowest temperature (7°, 6°), the temperature slowly increases downwards up to max. 9°; the temperature of the surface layers in summer, ranged from 13° in may to 25° – 26° in August.”