Drake Passage

The Drake Passage (Spanish: Pasaje de Drake) or Mar de Hoces—Sea of Hoces—is the body of water between South America's Cape Horn and the South Shetland Islands of Antarctica. It connects the southwestern part of the Atlantic Ocean (Scotia Sea) with the southeastern part of the Pacific Ocean and extends into the Southern Ocean.

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Drake Passage showing the boundary points A, B, C, D, E and F accorded by the Treaty of Peace and Friendship of 1984 between Chile and Argentina
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Tourist expedition ship Akademik Ioffe sailing across the Drake Passage to Antarctica
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Depth profile with salinity and temperature for surface

History

The passage receives its English-language name from the 16th-century English privateer Sir Francis Drake. Drake's only remaining ship, after having passed through the Strait of Magellan, was blown far south in September 1578. This incident implied an open connection between the Atlantic and Pacific oceans.

Half a century earlier, after a gale had pushed them south from the entrance of the Strait of Magellan, the crew of the Spanish navigator Francisco de Hoces thought they saw a land's end and possibly inferred this passage in 1525.[1] For this reason, some Spanish and Latin American historians and sources call it Mar de Hoces after Francisco de Hoces.

The first recorded voyage through the passage was that of Eendracht, captained by the Dutch navigator Willem Schouten in 1616, naming Cape Horn in the process.

Geography

The 800-kilometre (500 mi) wide passage between Cape Horn and Livingston Island is the shortest crossing from Antarctica to any other landmass. The boundary between the Atlantic and Pacific Oceans is sometimes taken to be a line drawn from Cape Horn to Snow Island (130 kilometres (81 mi) north of mainland Antarctica). Alternatively, the meridian that passes through Cape Horn may be taken as the boundary. Both boundaries lie entirely within the Drake Passage.

The other two passages around the extreme southern part of South America (though not going around Cape Horn as such), Strait of Magellan and Beagle Channel, are very narrow, leaving little room for a ship. They can also become icebound, and sometimes the wind blows so strongly that no sailing vessel can make headway against it. Hence most sailing ships prefer the Drake Passage, which is open water for hundreds of miles, despite very rough conditions. The small Diego Ramírez Islands lie about 100 kilometres (62 mi) south-southwest of Cape Horn.

There is no significant land anywhere around the world at the latitudes of Drake Passage, which is important to the unimpeded flow of the Antarctic Circumpolar Current which carries a huge volume of water (about 600 times the flow of the Amazon River) through the Passage and around Antarctica.

Ships in the Passage are often good platforms for the sighting of whales, dolphins and seabirds including giant petrels, other petrels, albatrosses and penguins.

Geology

The passage is known to have been closed until around 41 million years ago[2] according to a chemical study of fish teeth found in oceanic sedimentary rock. Before the passage opened, the Atlantic and Pacific Oceans were entirely separate, with Antarctica being much warmer and having no ice cap. The joining of the two great oceans started the Antarctic Circumpolar Current and cooled the continent significantly.

Gallery

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Rough seas are common in the Drake Passage

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Tourists watch whales in the Drake Passage

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Seabird (light-mantled sooty albatross) flying over the Drake Passage

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Humpback whales are a common sight in the Drake Passage

Hourglas dolphin crop

Hourglass dolphins leaping in the Passage

Drake Passage - Lambert Azimuthal projection

Drake Passage or Mar de Hoces between South America and Antarctica

Drake Passage - Orthographic projection

Drake Passage

See also

References

  1. ^ Oyarzun, Javier, Expediciones españolas al Estrecho de Magallanes y Tierra de Fuego, 1976, Madrid: Ediciones Cultura Hispánica ISBN 84-7232-130-4
  2. ^ Helen Briggs (21 April 2006). "Fossil gives clue to big chill". BBC News. Retrieved 1 November 2007.

External links

Media related to Drake Passage at Wikimedia Commons

Coordinates: 58°35′S 65°54′W / 58.583°S 65.900°W

Antarctic Circumpolar Current

The Antarctic Circumpolar Current (ACC) is an ocean current that flows clockwise from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and has a mean transport estimated at 100-150 Sverdrups (Sv, million m³/s), or possibly even higher, making it the largest ocean current. The current is circumpolar due to the lack of any landmass connecting with Antarctica and this keeps warm ocean waters away from Antarctica, enabling that continent to maintain its huge ice sheet.

Associated with the Circumpolar Current is the Antarctic Convergence, where the cold Antarctic waters meet the warmer waters of the subantarctic, creating a zone of upwelling nutrients. These nurture high levels of phytoplankton with associated copepods and krill, and resultant foodchains supporting fish, whales, seals, penguins, albatrosses, and a wealth of other species.

The ACC has been known to sailors for centuries; it greatly speeds up any travel from west to east, but makes sailing extremely difficult from east to west; although this is mostly due to the prevailing westerly winds. The circumstances preceding the mutiny on the Bounty and Jack London's story "Make Westing" poignantly illustrated the difficulty it caused for mariners seeking to round Cape Horn on the clipper ship route between New York and California. The clipper route, which is the fastest sailing route around the world, follows the ACC around three continental capes – Cape Agulhas (Africa), South East Cape (Australia), and Cape Horn (South America).

The current creates the Ross and Weddell gyres.

Beagle Channel

Beagle Channel (Spanish: Canal Beagle) is a strait in Tierra del Fuego Archipelago on the extreme southern tip of South America between Chile and Argentina. The channel separates the larger main island of Isla Grande de Tierra del Fuego from various smaller islands including the islands of Picton, Lennox and Nueva; Navarino; Hoste; Londonderry; and Stewart. The channel's eastern area forms part of the border between Chile and Argentina and the western area is entirely within Chile.

The Beagle Channel, the Straits of Magellan to the north, and the open-ocean Drake Passage to the south are the three navigable passages around South America between the Pacific and Atlantic Oceans. However, most commercial shipping uses the open-ocean Drake Passage.

The Beagle Channel is about 240 kilometres (130 nmi; 150 mi) long and is about 5 kilometres (3 nmi; 3 mi) wide at its narrowest point. It extends from Nueva Island in the east to Darwin Sound and Cook Bay of the Pacific Ocean in the west. Some 50 kilometres (27 nmi; 31 mi) from its western end it divides into two branches, north and south of Gordon Island. The southwest branch between Hoste Island and Gordon Island enters Cook Bay. The northwest branch between Gordon Island and Isla Grande enters Darwin Sound connecting to the Pacific Ocean by the O'Brien Channel and the Ballenero Channel. The biggest settlement on the channel is Ushuaia in Argentina followed by Puerto Williams in Chile. These are two of the southernmost settlements of the world.

Bistra Glacier

Bistra Glacier (Bulgarian: ледник Бистра, ‘Lednik Bistra’ \'led-nik 'bis-tra\) is 1 nautical mile (1.9 km; 1.2 mi) long and 0.4 nautical miles (0.74 km; 0.46 mi) wide glacier on the northwest side of Imeon Range on Smith Island in the South Shetland Islands, Antarctica. It is situated southwest of Chuprene Glacier and northwest of Dragoman Glacier, drains the west slopes of Mount Foster and the north slopes of Slaveykov Peak, and flows northwestwards of Zavet Saddle to enter Drake Passage south of Garmen Point.

The glacier is named after the settlements of Bistra in northeastern Bulgaria.

Boyd Strait

Boyd Strait is the 40-kilometre (25 mi) wide strait lying between Snow Island and Smith Island in the South Shetland Islands, Antarctica, and linking Drake Passage and the Bransfield Strait.

The strait was named in 1823 by a British expedition under James Weddell for Captain David Boyd, Royal Navy.

Cape Horn

Cape Horn (Spanish: Cabo de Hornos, pronounced [ˈkaβo ðe ˈoɾnos]) is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island. Although not the most southerly point of South America (which are the Diego Ramírez Islands), Cape Horn marks the northern boundary of the Drake Passage and marks where the Atlantic and Pacific Oceans meet.

Cape Horn was discovered and first rounded in 1616 by the Dutchman Willem Schouten, who named it Kaap Hoorn after the city of Hoorn in the Netherlands. For decades, Cape Horn was a major milestone on the clipper route, by which sailing ships carried trade around the world. The waters around Cape Horn are particularly hazardous, owing to strong winds, large waves, strong currents and icebergs; these dangers have made it notorious as a sailors' graveyard.

The need for boats and ships to round Cape Horn was greatly reduced by the opening of the Panama Canal in August 1914. However, sailing around the Cape Horn is still widely regarded as one of the major challenges in yachting. Thus a few recreational sailors continue to sail this route, sometimes as part of a circumnavigation of the globe. Almost all of these choose routes through the channels to the north of the Cape. (Many take a detour through the islands and anchor to wait for fair weather to visit Horn Island, or sail around it to replicate a rounding of this historic point.) Several prominent ocean yacht races, notably the Volvo Ocean Race, the VELUX 5 Oceans, and the Vendée Globe, sail around the world via the Horn. Speed records for round-the-world sailing are recognized for following this route.

Chuprene Glacier

Chuprene Glacier (Bulgarian: ледник Чупрене, ‘Lednik Chuprene’ \'led-nik chu-'pre-ne\) is a 2.1 nautical miles (3.9 km; 2.4 mi) long glacier draining the northwest slopes of Imeon Range on Smith Island in the South Shetland Islands, Antarctica. It is situated northeast of Bistra Glacier, southwest of Yablanitsa Glacier and northwest of Krivodol Glacier, Pashuk Glacier and Rupite Glacier, and flows southwest of Drinov Peak and Popovo Saddle, and west of Slatina Peak and Varshets Saddle southwestward along the northwest slopes of Antim Peak and Evlogi Peak into Drake Passage south of Villagra Point and north of Garmen Point. Bulgarian early mapping in 2009. The glacier is named after the settlement of Chuprene in northwestern Bulgaria.

Dalgopol Glacier

Dalgopol Glacier (Bulgarian: ледник Дългопол, ‘Lednik Galgopol’ \'led-nik d&l-go-'pol\) is a 1.8 nautical miles (3.3 km; 2.1 mi) long glacier draining the northwest slopes of Imeon Range on Smith Island in the South Shetland Islands, Antarctica. It is situated northeast of Vetrino Glacier and southwest of Kongur Glacier, and flows north of Mount Pisgah and northwest of Mezek Peak into Drake Passage. Bulgarian early mapping in 2009. The glacier is named after the town of Dalgopol in northeastern Bulgaria.

Kamchiya Glacier

Kamchiya Glacier (Lednik Kamchiya \'led-nik 'kam-chi-ya\) is located on Livingston Island in the South Shetland Islands, Antarctica situated south of the glacial divide between the Drake Passage and Bransfield Strait, and south of Tundzha Glacier, west-southwest of Pimpirev Glacier and east of Verila Glacier. The glacier extends 5 km along an east–west axis and is 2.2 km wide, draining into South Bay between Ereby Point and Memorable Beach.

The feature is named after the Kamchiya River in northeastern Bulgaria.

Kongur Glacier

Kongur Glacier (Bulgarian: ледник Конгур, ‘Lednik Kongur’ \'led-nik 'kon-gur\) is a 1.4 nautical miles (2.6 km; 1.6 mi) long glacier draining the northwest slopes of Imeon Range on Smith Island in the South Shetland Islands, Antarctica. It is situated northeast of Dalgopol Glacier and southwest of Saparevo Glacier, and flows west of Mount Christi into Drake Passage. Bulgarian early mapping in 2009. The glacier is named after the peak and nature reserve of Kongur on Belasitsa Mountain in southwestern Bulgaria.

Oligocene

The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present (33.9±0.1 to 23.03±0.05 Ma). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich; the name comes from the Ancient Greek ὀλίγος (olígos, "few") and καινός (kainós, "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period.

The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion of grasslands, and a regression of tropical broad leaf forests to the equatorial belt.

The start of the Oligocene is marked by a notable extinction event called the Grande Coupure; it featured the replacement of European fauna with Asian fauna, except for the endemic rodent and marsupial families. By contrast, the Oligocene–Miocene boundary is not set at an easily identified worldwide event but rather at regional boundaries between the warmer late Oligocene and the relatively cooler Miocene.

Phoenix Plate

The Phoenix Plate (also known as the Aluk or Drake Plate) was an ancient tectonic plate that existed during the mid-Cretaceous through early Cenozoic time. The remainder of the plate is now located east of the Drake Passage/Shackleton Fracture Zone.

The Phoenix Plate began subducting under the Antarctic Plate. The Phoenix Ridge, a mid-oceanic ridge between the Pacific and the Phoenix Plates which had a spreading rate of 18–20 cm per year until around 84 Ma. A major decrease in spreading rate, and the convergence rate with the Antarctic Plate occurred around 52.3 Ma. During the Late Cretaceous, the Phoenix Plate fragmented into the Charcot Plate, much in the same way in which the Rivera and the Cocos Plate were formed by the fragmentation of the Farallon Plate.The Antarctic-Phoenix Ridge (sometimes also called the Phoenix Ridge) consists of three extinct spreading ridge segments between the Antarctic Peninsula and the Scotia Sea. This ridge was initiated during the Late Cretaceous-Early Tertiary when the plate had divergent boundaries with the Bellingshausen and Pacific Plates. Bellingshausen was fused with the Antarctic Plate around 61 Ma and the Phoenix plate was gradually subducted by the Antarctic Plate as the Pacific-Antarctic Ridge propagated. The last collision between ridge crest segments and the subduction zone happened around 6.5 Ma and spreading had ceased entirely by 3.3 Ma when the small remnant of the Phoenix Plate was incorporated into the Antarctic Plate. The South Shetland Trough is the south-eastern boundary of the remnant and the Shackleton Fracture Zone is its north-eastern boundary.

Pimpirev Glacier

Pimpirev Glacier (Pimpirev Lednik \pim-'pi-rev 'led-nik\) on Livingston Island in the South Shetland Islands, Antarctica is situated south of the glacial divide between the Drake Passage and Bransfield Strait, southeast of Tundzha Glacier, southwest of Saedinenie Snowfield, west of Perunika Glacier and east-northeast of Kamchiya Glacier. The feature extends 5.5 km in a southeast-northwest direction, and 1.8 km in northwest-southeast direction. The glacier drains southeastwards towards Pimpirev Beach, mostly terminating on the shore, and on several occasions penetrating the South Bay waters east-northeast of Ereby Point.

The feature is named for Christo Pimpirev, geologist in the First Bulgarian Antarctic Expedition in 1987/88 and leader of subsequent national Antarctic campaigns. The original name Pimpirev Ice Wall was given on October 29, 1996 to the 50-m high rectilinear ice scarp-slope running parallelly to and some 100 m inland from the coast of South Bay northeast of Ereby Point. Reflecting subsequent changes in the ice cap configuration, the present name form was approved for the relevant glacier on November 4, 2005.

Saparevo Glacier

Saparevo Glacier (Bulgarian: ледник Сапарево, ‘Lednik Saparevo’ \'led-nik sa-pa-'re-vo\) () is a 1.8 km long and 2 km wide glacier draining the northwest slopes of Imeon Range on Smith Island, South Shetland Islands, Antarctica. It is situated northeast of Kongur Glacier, and flows north-northeast of Mount Christi and southwest of Matochina Peak into Vedena Cove in Drake Passage. Bulgarian early mapping in 2009. The glacier is named after the settlement of Saparevo in Southwestern Bulgaria.

Scotia Plate

The Scotia Plate (Spanish: Placa Scotia) is a tectonic plate on the edge of the South Atlantic and Southern Ocean. Thought to have formed during the early Eocene with the opening of the Drake Passage that separates South America from Antarctica, it is a minor plate whose movement is largely controlled by the two major plates that surround it: the South American plate and Antarctic plate.Roughly rhomboid, extending between 50°S 70°W and 63°S 20°W, the plate is 800 km (500 mi) wide and 3,000 km (1,900 mi) long. It is moving WSW at 2.2 cm (0.87 in)/year and the South Sandwich Plate is moving east at 5.5 cm (2.2 in)/year in an absolute reference frame. It takes its name from the steam yacht Scotia of the Scottish National Antarctic Expedition (1902–04), the expedition that made the first bathymetric study of the region.The Scotia Plate is made of oceanic crust and continental fragments now distributed around the Scotia Sea. Before the formation of the plate began 40 million years ago (40Ma), these fragments formed a continuous landmass from Patagonia to the Antarctic Peninsula along an active subduction margin. At present the plate is almost completely submerged, with only the small exceptions of the South Georgia Islands on its northeastern edge and the southern tip of South America.

Scotia Sea

The Scotia Sea is a sea located at the northern edge of the Southern Ocean at its boundary with the South Atlantic Ocean. It is bounded on the west by the Drake Passage and on the north, east, and south by the Scotia Arc, an undersea ridge and island arc system supporting various islands. The sea sits atop the Scotia Plate. It is named after the expedition ship Scotia.

Shackleton Fracture Zone

The Shackleton Fracture Zone (abbreviated as SFZ) is an undersea fracture zone and fault located in the Drake Passage, at the separation between the Scotia Plate from the Antarctic Plate. The Shackleton Fracture Zone runs in a northwest to southeast direction from the South American continental shelf to the South Shetland Islands.

Teteven Glacier

Teteven Glacier (Lednik Teteven \'led-nik 'te-te-ven\) is a glacier on Greenwich Island in the South Shetland Islands, Antarctica situated east of Yakoruda Glacier, west of Quito Glacier, northwest of Traub Glacier and north of Murgash Glacier. It extends 6.5 km in east-west direction and 3.8 km in north-south direction, and drains the north slopes of Dryanovo Heights into the Drake Passage in Haskovo Cove and Skaptopara Cove between Miletich Point and the ice-free area at Agüedo Point.

The glacier is named after the town of Teteven in the central Balkan Mountains, Bulgaria.

Tundzha Glacier

Tundzha Glacier (Lednik Tundzha \'led-nik 'tun-dzha\) is a glacier on Livingston Island in the South Shetland Islands, Antarctica situated east-southeast of Berkovitsa Glacier, west of Saedinenie Snowfield, northwest of Pimpirev Glacier, north of Kamchiya Glacier and east-northeast of Verila Glacier. It is bounded by Snow Peak to the west, Teres Ridge to the east and the glacial divide between the Drake Passage and Bransfield Strait to the south. The glacier extends 7.5 nautical miles (13.9 km; 8.6 mi) in east-west direction and 2.4 nautical miles (4.4 km; 2.8 mi) in the north-south direction, and drains northwards into Hero Bay between Avitohol Point and Siddins Point.

The feature was named after the Tundzha River in Bulgaria.

Vetrino Glacier

Vetrino Glacier (Bulgarian: ледник Ветрино, ‘Lednik Vetrino’ \'led-nik 've-tri-no\) is a 3.2 km long glacier on the northwest side of Imeon Range on Smith Island in the South Shetland Islands, Antarctica. It is situated northeast of Yablanitsa Glacier, southwest of Dalgopol Glacier and northwest of Ovech Glacier, drains the northwest slopes of Imeon Range north of Drinov Peak, northwest of Kostenets Saddle and west of Mount Pisgah, and flows northwestwards into Drake Passage both northeast and south of Gregory Point. The glacier is named after the town of Vetrino in northeastern Bulgaria.

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