1.
Atolls of the Maldives
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The Maldives are formed by a number of natural atolls plus atolls in the form of a few islands and isolated reefs today which form a pattern stretching from 7 degrees 10 North to 0 degrees 45 South. The Maldives is a long and narrow country formed by 26 natural atolls, some atolls are in the form of a number of islands by time and in the form of isolated reefs, which could be classified as smaller atoll formations. All land above the surface in the Maldives is of coralline origin, the atolls of the Maldives form a quite regular chain and, especially in the northern and central atolls, an arrayed structure is apparent. There are broad and deep channels in some atolls. The origin of the atoll itself is in the language of the Maldives. Atoll is now used in languages worldwide. Traditionally, Maldivians call the ending in -madulu or -mathi by their name without adding the word Atoll at the end. For example, it is correct to write simply Kolhumadulhu, without adding the word Atholhu at the end and this is also the case in the atoll known as Faadhippolhu. The atolls of the Maldives are very complex structures and formerly they were dangerous for navigators. These Admiralty charts were printed as three separate large maps by the Hydrographic Service of the Royal Navy, although they contain a few errors, Moresbys charts were so good that they were favoured by Maldivian pilots navigating through the treacherous waters of their atolls until the 1990s. Nowadays there are more accurate maps of the Maldives based on satellite surveys, however, Maldivian navigators still claim that Commander Moresbys charts provide a wealth of data that the modern maps dont give. At the time that they were drawn, the maps of the Maldives were deemed of such a quality that they were inspected personally by Queen Victoria. Owing to the many beautiful diving grounds of the atolls of the Maldives. Hence, during the last couple of decades many guides and maps of the best diving spots have been published and some of them are very accurate, the list below is a description of the atolls of the Maldives. Ihavandhippolhu Atoll is the northernmost atoll in the Maldives and it is a small natural atoll 22 km in length. It has 25 islands lying all around the boundary reef, one long barrier reef forms the western side of the atoll. There are several coral patches in the lagoon and the depth in the centre is 20 to 30 fathoms. Ihavandhippolhu is bounded in the north by the channel known as Māmalē Kandu which separates the islands of Maldives from those belonging to India
2.
Maldives
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The Maldives, officially the Republic of Maldives, is a South Asian island country, located in the Indian Ocean, situated in the Arabian Sea. It lies southwest of India and Sri Lanka, the chain of twenty-six atolls stretches from Ihavandhippolhu Atoll in the north to the Addu City in the south. Malé is the capital and most populated city, traditionally called the Kings Island for its central location. With an average elevation of 1.5 metres above sea level, it is the worlds lowest country, with even its highest natural point being the lowest in the world. Due to the subsequent risks posed by rising sea-levels, the government pledged in 2009 to make the Maldives a carbon-neutral country by 2019, the Maldives have been historically and culturally linked to the Indian subcontinent since the fourth century BCE. The Maldivian archipelago was Islamised in the 12th century and consolidated as a sultanate, developing commercial and cultural ties with Asia. From the mid 16th-century, the region came under the influence of European colonial powers. Independence from the United Kingdom was achieved in 1965 and a republic was established in 1968 with an elected Peoples Majlis. The ensuing decades have been characterised by political instability, efforts at democratic reform, the Maldives is a founding member of the South Asian Association for Regional Cooperation. It is also a member of the United Nations, the Organization of Islamic Cooperation, the World Bank classifies the Maldives as having an upper middle income economy. Fishing has historically been the dominant economic activity, and remains the largest sector by far, along with Sri Lanka, it is one of only two South Asian countries rated high on the Human Development Index, with its per capita income the highest among SAARC nations. The name Maldives may derive from the Malayalam words maala and dweepu or the Tamil maalai and theevu, the Maldivian people are called Dhivehin. The word theevu means island, and Dhives means islanders, the ancient Sri Lankan chronicle Mahawamsa refers to an island called Mahiladiva in Pali, which is probably a mistranslation of the same Sanskrit word meaning garland. Jan S Hogendorn, Grossman Professor of Economics, theorises that the name Maldives derives from the Sanskrit mālādvīpa, in Tamil, Garland of Islands can be translated as Malai Theevu. In Malayalam, Garland of Islands can be translated as Maladweepu, in Kannada, Garland of Islands can be translated as Maaledweepa. This is the name inscribed on the scroll in the Maldive state emblem. The classical Persian/Arabic name for Maldives is Dibajat, the Dutch referred to the islands as the Maldivische Eilanden, while the British anglicised the local name for the islands first to the Maldive Islands and later to Maldives. One such community are the Giraavaru people and they are mentioned in ancient legends and local folklore about the establishment of the capital and kingly rule in Malé
3.
South Asia
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Topographically, it is dominated by the Indian Plate, which rises above sea level as Nepal and northern parts of India situated south of the Himalayas and the Hindu Kush. South Asia is bounded on the south by the Indian Ocean and on land by West Asia, Central Asia, East Asia, the current territories of Afghanistan, Bangladesh, Bhutan, Maldives, Nepal, India, Pakistan, and Sri Lanka form the countries of South Asia. The South Asian Association for Regional Cooperation is an economic cooperation organisation in the region which was established in 1985, South Asia covers about 5.1 million km², which is 11. 51% of the Asian continent or 3. 4% of the worlds land surface area. The population of South Asia is about 1.749 billion or about one fourth of the worlds population, overall, it accounts for about 39. 49% of Asias population and is home to a vast array of peoples. The area of South Asia and its extent is not clear cut as systemic. Aside from the region of South Asia, formerly part of the British Empire, there is a high degree of variation as to which other countries are included in South Asia. Modern definitions of South Asia are consistent in including Afghanistan, India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan, Myanmar is included by some scholars in South Asia, but in Southeast Asia by others. Some do not include Afghanistan, others question whether Afghanistan should be considered a part of South Asia or the Middle East, the mountain countries of Nepal and Bhutan, and the island countries of Sri Lanka and Maldives are generally included as well. Myanmar is often added, and by various deviating definitions based on often substantially different reasons, the British Indian Ocean Territory, the common concept of South Asia is largely inherited from the administrative boundaries of the British Raj, with several exceptions. The Aden Colony, British Somaliland and Singapore, though administered at various times under the Raj, have not been proposed as any part of South Asia. Additionally Burma was administered as part of the Raj until 1937, the 562 princely states that were protected by but not directly ruled by the Raj became administrative parts of South Asia upon joining Union of India or Dominion of Pakistan. China and Myanmar have also applied for the status of members of SAARC. This bloc of countries include two independent countries that were not part of the British Raj – Nepal, and Bhutan, Afghanistan was a British protectorate from 1878 until 1919, after the Afghans lost to the British in the Second Anglo-Afghan war. The United Nations Statistics Divisions scheme of sub-regions include all eight members of the SAARC as part of Southern Asia, population Information Network includes Afghanistan, Bangladesh, Burma, India, Nepal, Pakistan and Sri Lanka as part of South Asia. Maldives, in view of its characteristics, was admitted as a member Pacific POPIN subregional network only in principle, the Hirschman–Herfindahl index of the United Nations Economic and Social Commission for Asia and the Pacific for the region includes only the original seven signatories of SAARC. The British Indian Ocean Territory is connected to the region by a publication of Janes for security considerations, the inclusion of Myanmar in South Asia is without consensus, with many considering it a part of southeast Asia and others including it within South Asia. Afghanistan was of importance to the British colonial empire, especially after the Second Anglo-Afghan War over 1878–1880, Afghanistan remained a British protectorate until 1919, when a treaty with Vladimir Lenin included the granting of independence to Afghanistan. Following Indias partition, Afghanistan has generally included in South Asia
4.
Indian Ocean
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The Indian Ocean is the third largest of the worlds oceanic divisions, covering 70,560,000 km2. It is bounded by Asia on the north, on the west by Africa, on the east by Australia, the Indian Ocean is known as Ratnākara, the mine of gems in ancient Sanskrit literature, and as Hind Mahāsāgar, in Hindi. The northernmost extent of the Indian Ocean is approximately 30° north in the Persian Gulf, the oceans continental shelves are narrow, averaging 200 kilometres in width. An exception is found off Australias western coast, where the width exceeds 1,000 kilometres. The average depth of the ocean is 3,890 m and its deepest point is Diamantina Deep in Diamantina Trench, at 8,047 m deep, Sunda Trench has a depth of 7, 258–7,725 m. North of 50° south latitude, 86% of the basin is covered by pelagic sediments. The remaining 14% is layered with terrigenous sediments, glacial outwash dominates the extreme southern latitudes. The major choke points include Bab el Mandeb, Strait of Hormuz, the Lombok Strait, the Strait of Malacca, the Indian Ocean is artificially connected to the Mediterranean Sea through the Suez Canal, which is accessible via the Red Sea. All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere is in this ocean, marginal seas, gulfs, bays and straits of the Indian Ocean include, The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April, from May until October south, in the Arabian Sea the violent Monsoon brings rain to the Indian subcontinent. In the southern hemisphere, the winds are milder. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea, the Indian Ocean is the warmest ocean in the world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, Indian Ocean warming is the largest among the tropical oceans, and about 3 times faster than the warming observed in the Pacific. Research indicates that human induced greenhouse warming, and changes in the frequency, among the few large rivers flowing into the Indian Ocean are the Zambezi, Shatt al-Arab, Indus, Godavari, Krishna, Narmada, Ganges, Brahmaputra, Jubba and Irrawaddy River. The oceans currents are controlled by the monsoon. Two large gyres, one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise, during the winter monsoon, however, currents in the north are reversed. Deep water circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, north of 20° south latitude the minimum surface temperature is 22 °C, exceeding 28 °C to the east. Southward of 40° south latitude, temperatures drop quickly, surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and south-western Australia
5.
India
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India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China, Nepal, and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the later peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Judaism, Zoroastrianism, Christianity, and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire. The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic, multilingual and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is also traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since then and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
6.
Island
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An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, an island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, an island may be described as such, despite the presence of an artificial land bridge. Example, Singapore and its causeway, or the various Dutch delta islands, there are two main types of islands in the sea, continental and oceanic. The word island derives from Middle English iland, from Old English igland, Old English ieg is actually a cognate of Swedish ö and German Aue, and related to Latin aqua. There is a difference between islands and continents in terms of geology, continents sit on continental lithosphere which is part of tectonic plates floating high on Earths mantle. Oceanic crust is also part of tectonic plates, but it is denser than continental lithosphere, Islands are either extensions of the oceanic crust or geologically they are part of some continent sitting on continental lithosphere. This holds true for Australia, which sits on its own continental lithosphere, continental islands are bodies of land that lie on the continental shelf of a continent. A special type of island is the microcontinental island, which is created when a continent is rifted. Examples are Madagascar and Socotra off Africa, the Kerguelen Islands, New Caledonia, New Zealand, another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. While some are transitory and may disappear if the volume or speed of the current changes, others are stable, oceanic islands are islands that do not sit on continental shelves. The vast majority are volcanic in origin, such as Saint Helena in the South Atlantic Ocean, the few oceanic islands that are not volcanic are tectonic in origin and arise where plate movements have lifted up the ocean floor above the surface. Examples are Saint Peter and Paul Rocks in the Atlantic Ocean, one type of volcanic oceanic island is found in a volcanic island arc. These islands arise from volcanoes where the subduction of one plate under another is occurring, examples are the Aleutian Islands, the Mariana Islands, and most of Tonga in the Pacific Ocean. The only examples in the Atlantic Ocean are some of the Lesser Antilles, another type of volcanic oceanic island occurs where an oceanic rift reaches the surface. There are two examples, Iceland, which is the second largest volcanic island, and Jan Mayen. A third type of oceanic island is formed over volcanic hotspots. A hotspot is more or less stationary relative to the tectonic plate above it
7.
Atoll
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An atoll, sometimes called a coral atoll, is a ring-shaped coral reef including a coral rim that encircles a lagoon partially or completely. There may be coral islands/cays on the rim, the coral of the atoll often sits atop the rim of an extinct seamount or volcano which has eroded or subsided partially beneath the water. The lagoon forms over the crater or caldera while the higher rim remains above water or at shallow depths that permit the coral to grow. For the atoll to persist, continued erosion or subsidence must be at a slow enough to permit reef growth upwards and outwards to replace the lost height. The word atoll comes from the Dhivehi word atholhu, meaning an administrative subdivision, the distribution of atolls around the globe is instructive, most of the worlds atolls are in the Pacific Ocean and Indian Ocean. The Atlantic Ocean has no large groups of atolls, other than eight atolls east of Nicaragua that belong to the Colombian department of San Andres and Providencia in the Caribbean. Reef-building corals will thrive only in tropical and subtropical waters of oceans and seas. The northernmost atoll of the world is Kure Atoll at 28°24 N, the southernmost atolls of the world are Elizabeth Reef at 29°58 S, and nearby Middleton Reef at 29°29 S, in the Tasman Sea, both of which are part of the Coral Sea Islands Territory. The next southerly atoll is Ducie Island in the Pitcairn Islands Group, at this latitude coral reefs would not develop without the warming waters of the Gulf Stream. However, Bermuda is termed a pseudo-atoll because its general form, while there is no atoll directly on the equator, the closest atoll to the Equator is Aranuka of Kiribati, with its southern tip just 12 km north of the equator. In most cases, the area of an atoll is very small in comparison to the total area. Atoll islands are low lying, with their elevations less than 5 meters, measured by total area, Lifou is the largest raised coral atoll of the world, followed by Rennell Island. More sources however list as the largest atoll in the world in terms of land area Kiritimati, the remains of an ancient atoll as a hill in a limestone area is called a reef knoll. The second largest atoll by dry land area is Aldabra with 155 km², the largest atoll in terms of island numbers is Huvadhu Atoll in the south of the Maldives with 255 islands. In 1842, Charles Darwin explained the creation of coral atolls in the southern Pacific Ocean based upon observations made during a voyage aboard the HMS Beagle from 1831 to 1836. In time, subsidence carries the old volcano below the ocean surface, at this point, the island has become an atoll. Atolls are the product of the growth of marine organisms. Volcanic islands located beyond the water temperature requirements of hermatypic organisms become seamounts as they subside and are eroded away at the surface
8.
Coral reef
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Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals. Coral reefs are built by colonies of tiny animals found in waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups, the polyps belong to a group of animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons which support, most reefs grow best in warm, shallow, clear, sunny and agitated waters. Often called rainforests of the sea, shallow coral reefs form some of the most diverse ecosystems on Earth, paradoxically, coral reefs flourish even though they are surrounded by ocean waters that provide few nutrients. They are most commonly found at depths in tropical waters. Coral reefs deliver ecosystem services to tourism, fisheries and shoreline protection, the annual global economic value of coral reefs is estimated between US$29. 8-375 billion. However, coral reefs are fragile ecosystems, partly because they are sensitive to water temperature. Most of the coral reefs we can see today were formed after the last glacial period when melting ice caused the sea level to rise and this means that most modern coral reefs are less than 10,000 years old. As communities established themselves on the shelves, the reefs grew upwards, Reefs that rose too slowly could become drowned reefs. They are covered by so much water there was insufficient light. Coral reefs are found in the sea away from continental shelves, around oceanic islands. The vast majority of islands are volcanic in origin. The few exceptions have tectonic origins where plate movements have lifted the deep ocean floor on the surface. In 1842 in his first monograph, The Structure and Distribution of Coral Reefs, Charles Darwin set out his theory of the formation of atoll reefs and he theorized uplift and subsidence of the Earths crust under the oceans formed the atolls. Darwin’s theory sets out a sequence of three stages in atoll formation and it starts with a fringing reef forming around an extinct volcanic island as the island and ocean floor subsides. As the subsidence continues, the reef becomes a barrier reef. Darwin predicted that underneath each lagoon would be a bed rock base, where the level of the underlying earth allows, the corals grow around the coast to form what he called fringing reefs, and can eventually grow out from the shore to become a barrier reef
9.
Shoal
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Often it refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravelbars, two or more shoals that are either separated by shared troughs or interconnected by past and or present sedimentary and hydrographic processes are referred to as a shoal complex. The term shoal is also used in a number of ways that can be similar or quite different from how it is used in the geologic, geomorphic. Shoals are characteristically long and narrow ridges and they can develop where a stream, river, or ocean current promotes deposition of sediment and granular material, resulting in localized shallowing of the water. Marine shoals also develop either by the in place drowning of barrier islands as the result of sea level rise or by the erosion. Shoals can appear as a coastal landform in the sea, where they are classified as a type of bank, or as fluvial landforms in rivers, streams. A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as, Marine lagoons Brackish water estuaries Freshwater seasonal stream and river mouths and deltas. They are typically composed of sand, although they could be of any matter that the moving water has access to and is capable of shifting around. Wave shoaling is the process when surface waves move towards shallow water, such as a beach, they slow down, their wave height increases and this behavior is called shoaling, and the waves are said to shoal. The waves may or may not build to the point where they break, depending on how large they were to begin with, in particular, waves shoal as they pass over submerged sandbanks or reefs. This can be treacherous for boats and ships, shoaling can also diffract waves, so the waves change direction. For example, if waves pass over a bank which is shallower at one end than the other. Thus the wave fronts will refract, changing direction like light passing through a prism, refraction also occurs as waves move towards a beach if the waves come in at an angle to the beach, or if the beach slopes more gradually at one end than the other. Sandbars, also known as a trough bars, form where the waves are breaking, sometimes this occurs seaward of a trough. Sand carried by the moving bottom current is deposited where the current reaches the wave break. Other longshore bars may lie further offshore, representing the point of even larger waves. A harbor or river bar is a sedimentary deposit formed at an entrance or river mouth by. Where beaches are suitably mobile, or the river’s suspended and/or bed loads are large enough, deposition can build up a sandbar that completely blocks a river mouth and damming the river
10.
Mid-ocean ridge
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A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
This article incorporates public domain material from the Library of Congress Country Studies website http://lcweb2.loc.gov/frd/cs/.
This article incorporates 