Istanbul’s cow-ford strait still splits two continents
The Bosporus is the Turkish strait linking the Black Sea to the Sea of Marmara, pairing with the Dardanelles as the Turkish Straits and marking a continental seam between Asia and Europe. Istanbul’s metro population of some 17 million climbs both banks, leaving only northern stretches lightly settled.
The strait separates Asia Minor from Thrace and is the narrowest waterway in the world used by international shipping. Measured between lighthouses at each end, it runs 31 kilometres, about 3,329 metres wide at the northern mouth, 2,826 metres at the southern and 3,420 metres at its widest near Büyükdere. Midstream depth ranges from 13 metres off Aşiyan Point to 110 metres between Kandilli and Bebek, averaging 65. Parts of the shore are armoured with concrete or rubble, and silting stretches are dredged. As the only sea passage between the Black Sea and the Mediterranean, it has long mattered commercially and militarily, remains vital for countries such as Russia and Ukraine, and was a prize in conflicts like the Russo-Turkish War of 1877 to 1878.
Water moves both ways at once. About 16,000 cubic metres per second of fresher water flows south at the surface while roughly 11,000 of salt water pushes north along the bottom. In August 2010 a University of Leeds team using a robotic submarine mapped a channel of dense, sediment-laden flow on the floor big enough that, placed on dry land, it would rank sixth among the planet's rivers; at bends it spirals the opposite way from rivers ashore. Earlier surveys by NATO in 1999 and French researchers in 2002 had already revealed the scale of the channels.
How the strait formed is still argued. The Black Sea deluge hypothesis, published in 1997 by two Columbia University scientists, proposes that rising Mediterranean waters burst through around 5600 BC, a date later revised to 6800 BC, swelling a freshwater lake by half; Robert Ballard's discovery of drowned settlements lent support. Many geologists think the strait is considerably older.
The name was popularly read as cattle passage, after the myth of Io, who, turned into a cow, crossed here and met Prometheus; she supposedly landed near Chrysopolis, today's Üsküdar. The -ph- spelling came from medieval Latin and Greek rather than the ancient form. The shores were once fishing villages reachable only by caique, and many suburbs still carry the suffix -köy, village.
Source: Bosporus
