Concept

Black Sea

Overview

The Black Sea is a marginal sea located between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bordered by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is supplied by major rivers, principally the Danube, Dnieper and Dniester. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe.

The Black Sea, not including the Sea of Azov, covers 436,400 km2 (168,500 sq mi), has a maximum depth of 2,212 m (7,257 ft), and a volume of 547,000 km3 (131,000 cu mi).

Most of its coasts ascend rapidly.

These rises are the Pontic Mountains to the south, the southwest-facing peninsulas, the Caucasus Mountains to the east, and the Crimean Mountains to the mid-north.

In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end of the Balkan Mountains; and the Dobruja Plateau considerably farther north. The longest east–west extent is about 1,175 km (730 mi). Important cities along the coast include (clockwise from the Bosporus) the northern suburbs of Istanbul, Burgas, Varna, Constanța, Odesa, Yevpatoria, Sevastopol, Yalta, Kerch, Novorossiysk, Sochi, Poti, Batumi, Rize, Trabzon, Ordu, Samsun and Zonguldak.

The Black Sea has a positive water balance, with an annual net outflow of 300 km3 (72 cu mi) per year through the Bosporus and the Dardanelles into the Aegean Sea. While the net flow of water through the Bosporus and Dardanelles (known collectively as the Turkish Straits) is out of the Black Sea, water generally flows in both directions simultaneously: Denser, more saline water from the Aegean flows into the Black Sea underneath the less dense, fresher water that flows out of the Black Sea. This creates a significant and permanent layer of deep water that does not drain or mix and is therefore anoxic. This anoxic layer is responsible for the preservation of ancient shipwrecks which have been found in the Black Sea, which ultimately drains into the Atlantic Ocean, via the Turkish Straits and the Aegean Sea into the Mediterranean Sea, and from it to the Atlantic proper through the Strait of Gibraltar. The Bosporus strait connects it to the small Sea of Marmara which in turn is connected to the Aegean Sea via the strait of the Dardanelles. To the north, the Black Sea is connected to the Sea of Azov by the Kerch Strait.

The water level has varied significantly over geological time. Due to these variations in the water level in the basin, the surrounding shelf and associated aprons have sometimes been dry land. At certain critical water levels, connections with surrounding water bodies can become established. It is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the World Ocean. During geological periods when this hydrological link was not present, the Black Sea was an endorheic basin, operating independently of the global ocean system (similar to the Caspian Sea today). Currently, the Black Sea water level is relatively high; thus, water is being exchanged with the Mediterranean. The Black Sea undersea river is a current of particularly saline water flowing through the Bosporus Strait and along the seabed of the Black Sea, the first of its kind discovered.

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

Possible passages

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These fish, he says, are of such enormous strength, that with their teeth they seize hold of the trunks of elephants that come to drink, and so drag them into the water. The Black Sea is never entered by any animal that is noxious to fish, with the exception of the sea-calf and the small dolphin. On entering, the tunnies range along the shores to the right, and on departing, keep to those on the left; this is…
the Elder Pliny, The Boys' and Girls' Pliny
States what Black Sea is; names Black Sea several times.
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In this we have a portion of the water of the river which is not the smallest nor the least famous, and it is called the Sebennytic mouth.
Herodotus, An Account of Egypt
States what Black Sea is.
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This is that Pyriphlegethon, as the stream is called, which throws up jets of fire in different parts of the earth. The fourth river goes out on the opposite side, and falls first of all into a wild and savage region, which is all of a dark-blue colour, like lapis lazuli; and this is that river which is called the Stygian river, and…
Plato, Phaedo
States what Black Sea is.
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Black Sea

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