The Black Sea is not large (450,000 square kilometers). It is a landlocked sea, situated between Europe and Asia, and connected with the Mediterranean Sea by the narrow Straits of the Bosphorus and the Dardanelles and the Sea of Marmora, which, geologically speaking, is a basin formed by subsidence. Great subsidences of the earth’s surface created the deep basin of the Pontus. The Pontus was a part of the extensive upper Miocene and Sarmatian inland sea, which slightly flooded large districts of the present European continent as far as the Vienna basin. Toward the end of the tertiary period, this inland sea shrank and separated into single sea basins. The Pontian basin became connected with the Mediterranean Sea later, in the latter part of the diluvial period, by means of great subsidences of recent date.
The present morphology of the Pontus is in full accord with this genesis. The northern part, as far as the line of communication between the Balkan and Yaila Mountains, is a shallow sea of a depth of less than 200 meters; the so-called bay of Odessa is barely 50 meters deep; the Sea of Azof, projecting to the northeast, barely 15 meters. But just on the southern border of the line of plicated mountains, which is broken at this point, the bottom of the Black Sea declines rapidly to greater depths (1500 meters) until, declining more gradually now, it attains the depth [[17]]of 2245 meters in the center of the oval-shaped main basin of the Pontus.
The salt content of the Black Sea is much smaller than that of the ocean, or even of the Mediterranean. The Sea is comparatively small, and receives a great deal of fresh water from the many and large rivers of the region which it drains, while the influx of salt water from the Mediterranean thru the shallow straits cannot be great. The salt content is on the average 1.8%; only at great depths does it reach 2.2%. The diluted surface layer shows barely 1.5% salt content; the Sea of Azof hardly 1%. The surface water, containing little salt but a great deal of air, cannot, because of the greater density of the lower layers of water, sink far, and this low degree of ventilation accounts for the fact that the waters of the Black Sea below a depth of 230 meters are saturated with sulphide of hydrogen, and thus preclude any possibility of organic deep-sea life.
Nevertheless, the Black Sea is notable for its beautiful blue-green color and the great transparency of its waters. A white disc, on being submerged, disappeared only at a depth of 77 meters.
The surface temperature of the Black Sea is subject to many fluctuations; from 27° C in midsummer to 5° C in winter. In severe winters the Sea is frozen over in the bay of Odessa for a short time; the Limans and the Sea of Azof regularly for from two to three months.
The Black Sea has been known since hoary antiquity as a dangerous, stormy sea. The waves, running as high as 10 meters, the short cross-waves caused by the proximity of the shores, the difficult approaches to the land, are still a great hindrance to navigation, especially in the winter time. Not without cause did the Greeks originally call it “the inhospitable sea,” until the great number of flourishing Greek settlements on its shores led them to change its name [[18]]to “hospitable sea.” Despite this euphemistic name, however, “Pontus Euxeinos,” the Black Sea has devoured many goods and lives, many Greek and Roman ships, many Turkish and Genoese galleys, many English and Russian steamers. And many a little Zaporog vessel sank in the dark waves of its native sea, “on white cliffs dashed to pieces,” as is related in the old folk-epics; many a one was driven to far-off hostile Turkish shores, to the destruction of its crews.
Being a closed interior sea, the Pontus has no noticeable tides. Marked changes of level are caused by the action of the wind. In the liman of the Boh, for example, they produce 20 centimeters difference of level in a day, sometimes even 40 centimeters; in the bay of Yahórlik as much as 46 centimeters. The Sea of Azof becomes 45 to 90 centimeters deeper when there is a west wind, up to 1 meter deeper in the case of south winds, and shallower by an equal amount when the winds are in the opposite direction. Slight changes of level are dependent also on the seasons. The Black Sea has its lowest water level in February, when the region which it drains is covered with snow; the highest in May and June, as a result of the melting of the snows and the early summer rains. These fluctuations, however, amount to only 25 cm. The currents of the Black Sea, too, are inconsiderable, because of its isolation. Outside of local currents which are caused by winds, we know of only one greater current, weak in itself, which encircles the Pontian Basin in a counter clock-wise direction and may be traced to the cyclonal motion of the air. The same conditions obtain on a smaller scale on the Sea of Azof and are reflected in the direction of the tongues of land along the coasts.
Despite the fact that the deep-sea region of the Black Sea is poisoned with sulphide of hydrogen, it possesses a rich flora and fauna in its surface layers. Enormous [[19]]shoals of all kinds of fish—sturgeon, hausen, sterlet, “kephal,” “bichok,” “balmut,” come to the coast and into the limans of the river deltas. For this reason the Pontian fishing industry has been considerable for thousands of years. The extraction of salt from the limans and salt lakes is also important. Before the age of the railroad the abundance of fish and salt of the Black Sea created a special trucking trade in the Ukraine, the so-called Chumaki, who came to the Pontian strand in whole caravans of oxcarts to take dried fish and salt in exchange for grain.
The Ukrainian coast of the Black Sea begins at the delta of the Danube and ends at the western spurs of the Caucasus. The greater part is flat coast, the smaller, steep coast.
At the northern Kilian arm of the Danube delta, where now the descendants of the Zaporog Cossacks gain a scanty living thru fishing, begins the coast of the Ukraine. The steppe approaches the sea with a steep declivity, which is bordered by a narrow strand of sand and pebbles. The coast runs evenly as far as the Dnieper delta, without any indentations. Even the famous port of Odessa is an artificial harbor.