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Speakers Bank
Speakers Bank is a large coral atoll structure in the Northwestern part of the Chagos Archipelago. It is the northernmost feature of the archipelago, located at , 22 km Northwest of Blenheim Reef and is 44 km Northeast-Southwest, and 24 km wide. The total area is 582 km2, most of which is water. Most of the rim of the reef is between 5.5 and 14.5 metres below water. In the south, near the southwest edge, there are some coral heads at 05°04'S, 072°16'E, 0.5 metres of which are dry during low tide, and over which the sea breaks heavily during the southeast trade winds. In the Northeast, at 04°47'S, 072°26'E, there are a number of drying cays, the biggest of which, Big Speaker Reef, just reaches the high water mark. The land area is negligible. Speakers Bank was surveyed in 1856 by British captain J. Speaker on HMS Wallerup. It is the site of many wrecks, also from prior times.British Admiralty nautical chart A nautical chart is a graphic representation of a sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which, when m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atoll
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can grow. Most of the approximately 440 atolls in the world are in the Pacific Ocean. Two different, well-cited models, the subsidence and antecedent karst models, have been used to explain the development of atolls.Droxler, A.W. and Jorry, S.J., 2021. ''The Origin of Modern Atolls: Challenging Darwin's Deeply Ingrained Theory.'' ''Annual Review of Marine Science'', 13, pp.537-573. According to Charles Darwin's ''subsidence model'', the formation of an atoll is explained by the subsidence of a volcanic island around which a coral fringing reef has formed. Over geologic time, the volcanic island becomes extinct and eroded as it subsides completely beneath the surface of the ocean. As the volcanic island subsides, the coral fringing reef becomes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chagos Archipelago
The Chagos Archipelago () or Chagos Islands (formerly the Bassas de Chagas, and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives archipelago. This chain of islands is the southernmost archipelago of the Chagos–Laccadive Ridge, a long submarine mountain range in the Indian Ocean. In its north are the Salomon Islands, Nelson's Island and Peros Banhos; towards its south-west are the Three Brothers, Eagle, Egmont and Danger Island(s); southeast of these is Diego Garcia, by far the largest island. All are low-lying atolls, save for a few extremely small instances, set around lagoons. The Chagos Islands had been home to the native Chagossians, a Bourbonnais Creole-speaking people, until the United Kingdom expelled them from the archipelago at the request of the United States between 1967 and 1973 to allow the United States to build a military base on Diego Garcia. Since 197 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blenheim Reef
Blenheim Reef is a partly submerged atoll structure in the Chagos Archipelago, Indian Ocean. It includes the coral reef of Baxio Predassa in its southeastern rim, plus another completely submerged part. It is located in the northeastern part of the Chagos Archipelago. It measures almost eleven kilometres (north–south) by more than four kilometres (east–west), with a total area of 36.8 square kilometres, including the lagoon of 8.5 km², the difference being accounted for the mostly by the reef flat. Only on the eastern side, there are a few sand cays above the water. The largest of them is East Island, which is not quite 200 metres long and 70 metres wide. The other islands in the group are North, Middle and South. Only a few grasses grow on the island. The lagoon is up to 18 metres deep and encumbered with rock. The fringing coral reef has a wide passage in the southwest. The closest land is Takamaka Island in the Salomon Islands Ato ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trade Winds
The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase. Trade winds have been used by captains of sailing ships to cross the world's oceans for centuries. They enabled colonial expansion into the Americas, and trade routes to become established across the Atlantic Ocean and the Pacific Ocean. In meteorology, they act as the steering flow for tropical storms that form over the Atlantic, Pacific, and southern Indian oceans and make landfall in North America, Southeast Asia, and Madagascar and East Africa. Shallow cumulus clouds are seen within trade wind regimes and are capped from becoming taller by a trade wind inversion, which is caused by descending air aloft from within the subtropical ridge. The weak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Britain
Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is dominated by a maritime climate with narrow temperature differences between seasons. The 60% smaller island of Ireland is to the west—these islands, along with over 1,000 smaller surrounding islands and named substantial rocks, form the British Isles archipelago. Connected to mainland Europe until 9,000 years ago by a landbridge now known as Doggerland, Great Britain has been inhabited by modern humans for around 30,000 years. In 2011, it had a population of about , making it the world's third-most-populous island after Java in Indonesia and Honshu in Japan. The term "Great Britain" is often used to refer to England, Scotland and Wales, including their component adjoining islands. Great Britain and Northern Ireland now constitute the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Admiralty
The Admiralty was a department of the Government of the United Kingdom responsible for the command of the Royal Navy until 1964, historically under its titular head, the Lord High Admiral – one of the Great Officers of State. For much of its history, from the early 18th century until its abolition, the role of the Lord High Admiral was almost invariably put "in commission" and exercised by the Lords Commissioner of the Admiralty, who sat on the governing Board of Admiralty, rather than by a single person. The Admiralty was replaced by the Admiralty Board in 1964, as part of the reforms that created the Ministry of Defence and its Navy Department (later Navy Command). Before the Acts of Union 1707, the Office of the Admiralty and Marine Affairs administered the Royal Navy of the Kingdom of England, which merged with the Royal Scots Navy and the absorbed the responsibilities of the Lord High Admiral of the Kingdom of Scotland with the unification of the Kingdom of Great ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Chart
A nautical chart is a graphic representation of a sea area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land (topographic map), natural features of the seabed, details of the coastline, navigational hazards, locations of natural and human-made aids to navigation, information on tides and currents, local details of the Earth's magnetic field, and human-made structures such as harbours, buildings, and bridges. Nautical charts are essential tools for marine navigation; many countries require vessels, especially commercial ships, to carry them. Nautical charting may take the form of charts printed on paper (raster navigational charts) or computerized electronic navigational charts. Recent technologies have made available paper charts which are printed "on demand" with cartographic data that has been downloaded to the commercial printing company as recently as the night before printing. With each daily download, critica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
