Summary of Black Sea Lnvestigations1 Southeastern Black Sea to Gain The
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Summary of Black Sea lnvestigations1 K. 0. EMERY and J. M. HUNT' Abstract The Black Sea consists of a shelf, basin southeastern Black Sea to gain the Golden slope, bosin opron, ond Iorge ond smoll abyssal plains. Fleece. In more prosaic terms, the Greek cruise Its maximum depth is 2,206 m and water volume is 534,000 km3, of which about 90 percent is anaerobic. which was made about that time was designed It contains 8-14 km of sedimentary units; the thickest for, and succeeded in, the theft of sheepskins part is in the central basin area. Basin slopes are under that hard-working placer miners used to floor loin by buried peripheral ridges and troughs similar to sluice boxes in order to trap fine-grained gold. those of known coastal oil-producing regions. The sedi mentary units are underlain by 0-15 km of presumably This voyage was the beginning of a major metamorphic rocks which thicken landward. An addi change in the trade lines of civilization-from tional 6-22 km of basaltic rocks overlies the Mohorovicic the perilous land routes that had created the discontinuity. The sea was formed from eugeosynclines wealth of Egypt and the Near East to water that dale from Early Jurassic time. Numerous coastal terraces ranging up to 105 m above sea level show routes. These water routes developed from that deformation is still active. The sea was a fresh Europe and Africa into Asia through the water lake during the Wiirm glacial stage, and the Aegean and Black Seas, causing a shift in the later invasion of seawater caused stratification and center of wealth. As Egypt, Mesopotamia, and forma:ion of an cn:�erobic layer, which is now 200 m below the sea surface and is still rising. Water at 300 m then Persia withered, Phoenicia and Greece is 900 years old; the age increases to 2,000 years at blossomed. What drew mariners to the Aegean 2,000 m. Trace metals such as iron and manaanese area were the islands, strewn like jewels in all diffuse upward from the hydrogen sulfide water and directions so that ships could sail east, west, are precipitated in the oxygenated water, causing a high concentration of suspended pariicles above the north, or south and never be more than 40 mi hydrogen sulfide-oxygen interface. The sediments in from land. The mountains were a welcome clude cocco:ith ooze, sapropel beds, and banded lutites beacon to ships that had no compass to guide in the basins, and silt and s:�nd on the shelves. them. The Greeks called the Mediterranean Ho Annu:�l river inflow of 374 km3 includes about 150 million tons of solids in suspension. O:ganic carbon Pontos, the "passage" or "road," and the Black in sediments ranges from 0.5 percent in those deposited Sea was termed Ho Pontos Euxeinos, the "pas during the freshwa!er era to 5-15 percent in the pre sage kindly to guests," probably because its dominantly land-derived sediments deposited in the coastal currents carried their ships north to brackish-water environment. Anaero�ic bacteria, which form the bulk of the hydrogen sulfide by reduction of fetch grains, fish, and furs, and its strong cen dissolved sulfate, were identified near the hydrogen tral current flowed south to carry the mariners sulfide-oxygen water interface. Studies of Sr81 /Sr86 ratios home. Also, the northeasterly winds blew regu in the carbonates of the sediments show that shells in the daeper co:es are reworked from Cretaceous-Tertiary larly in the summer to help ships back to sedimentary units. Reactive ferrous iron is concentrated southern ports. The modern name is a transla in the deep-water sediments as hydrotroilite and pyrite, tion of Karadeniz (black), the name given to in contrast with unreactive ircn, which is present as the sea by the Turks, who feared its stormy magnetite and hem:�tite on the shelves. Methane focming in the sediments diffuses upward into the water where expanse. it recches concen"rclions of 0.1 ml/1 in the hyp:>limn:on As the Greeks moved north into the Black comp:Jred with about 7 ml/1 in the oxygenated Sea seeking grain, furs, metal, and trade, they X w-' wa:·ers. A comparison of the Bbck Sea, Red Se:�, and founded one city after another along the south Dac:d Sea shows wide ranges in water composition, sediment properties, and o:ganic activity that are con ern, eastern, and western shores of the sea. trolled by the position of the bos'n sills relative to the Strabo mentioned Sinope, where the cynic Di fluctuating level of the open ocean. ogenes was born, as a city splendidly adorned with gymnasium, agora, and shady colonnades. INTRODUCTION Trapezus, on the south shore, is where Xen- Manuscript received, March 9, 1972. Woods Hole The earEest description of the Black Sea is 1 in the legendary "Voyage of the Argonauts," Oceanographic Institution Contribution No. 2831. 2 Woods Hole Oceanographic Institution, Woods which is supposed to have occurred about 3,200 Hole, Massachusetts. years ago. Jason and his crew of heroes sailed This research was supported by National Science aboard Argo to the coast of Colchis in the Foundation Grants GA-1659 and GA-25234. 575 Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3839728/9781629812151_backmatter.pdf by guest on 23 September 2021 576 K. 0. Emery and J. M. Hunt ophon's 10,000 shouted with joy at the sight 25,000 stadia. These measurements correspond of the longed-for sea. to 1,100, 390, and 3,900 km, if 700 of Strabo's Around 660 B.C., Byzantium (now Istan stadia equal 1 degree of latitude-and they are bul) was built, and the city soon grew rich by nearly correct. Many other geographic details exacting tolls from passing vessels and export (topography, names of cities, etc.) were noted ing the grain of southern Russia (Scythia) to for the Black Sea region by Strabo, showing Greece. Also exported were the fish that were that the region had become well traveled and easily netted as they crowded through the nar well known. Similar descriptions were provided row straits. Under Pericles, the Greeks levied about 50 years later by Pliny (Books IV and tolls at Byzantium and regulated the export of VI), indicating that he might have used the grain from the Black Sea as a contraband of same source materials. war. Generations later, Napoleon was to call Strato (according to Strabo-Book I, chap. this strategic port "the key to Europe." 3) was of the opinion that there formerly was Prosperity of the region led Persian King no exit from the Black Sea, but that the rivers Darius I to build a bridge of ships. across the entering it had eventually forced their way Hellespont to invade Greece, where he was de through the Bosporus. He suggested that this feated at Marathon in 490 B.C. His son, Xerxes, river flow accounts for the low salinity of the assembled a larger army and a navy largely Black Sea as well as its infilling with sedi contributed by the Phoenicians. His army also ments. Strabo also wrote that Posidonius, Hip crossed the Hellespont by a double-pontoon parchus, and Eratosthenes thought the flow in bridge, defeated the Greek guard under Leo the Bosporus to be in one direction, away from nidas at Thermopylae, and captured Athens. the Black Sea, not reversing itself twice a day However, when his fleet was destroyed by the as a tide following the moon; furthermore, they Greeks under Themistocles at Salamis in 480 thought there was no flow at all at times. B.C., Xerxes' army had to withdraw. At the The role of the Bosporus as a passage for time of the invasion by Darius, his ships mea navies and a barrier for armies continued sured the dimensions of the Black Sea (as re through the Crusades. When the armies of the corded by Herodotus, Book IV, chap. 86) in First Crusade reached Constantinople (Byzan terms of days and nights of sailing. These mea tium) in 1096-1097 A.D., they were ferried surements convert to 2,050 by 600 km. The across the Bosporus and given supplies by the dimensions are nearly double the actual ones, Greek. Orthodox bishop Alexis to keep the but their ratio is correct. Herodotus also re city safe from pillage. The largely Latin Fourth ferred to the shape of the southern shore as Crusade in 1202-1204 A.D. was diverted and similar to that of a Scythian bow with recurved captured Constantinople-never crossing the tips. More detailed measurements of the Bos Bosporus in force. Nothing seems to have been porus, the Sea of Marmara (Propontus), and learned about the Black Sea by the crusaders, the Dardanelles (Hellespont) were noted in who considered it only as an obstacle to be connection with the building of the pontoon avoided. In 1453, when ships of the Venetian bridge. Herodotus' descriptions of the rivers allies failed to arrive in time to help the Greeks, that drain into the Black Sea, and of the Sea of Constantinople was captured again, by the Otto Azov, provide evidence of his own observations man Turk Sultan Mahmud II, and renamed and of good information by others who had "Istanbul." For the next 300 years the Turks visited the numerous Greek colonies along the excluded all ships except their own from the shores. In fact, by 350 B.C., about half of Black Sea. In 1774 the right to trade was ceded Athen's grain came from the vicinity of the Sea to the Russians in the Treaty of Kainarji, and of Azov.