What Is a Atoll Geography Definition

The word atoll comes from the Dhivehi word atholhu (Dhivehi: ), Dhivehi is an Indo-Aryan language spoken in the Maldives. The first recorded English use of the word was in 1625 as an atollon. Charles Darwin coined the term in his monograph The Structure and Distribution of Coral Reefs. He recognized the indigenous origin of the word and defined it as a “circular group of coral islands,” synonymous with “lagoon island.” [6]:2 In 1842, Charles Darwin[6] explained the formation of coral atolls in the South Pacific Ocean based on observations made during a five-year voyage aboard HMS Beagle from 1831 to 1836. Darwin`s explanation suggests that several types of tropical islands: from tall volcanic islands to coral reef islands to atolls, represented a sequence of gradual subsidence of what began as an oceanic volcano. He argued that a fringing coral reef surrounding a volcanic island in the tropical sea will grow upward as the island sinks (sinks) and becomes a “nearby atoll” or barrier reef island, as it crosses an island like Aitutaki in the Cook Islands and Bora Bora and others in the Society Islands. The fringing reef becomes a coral reef as the outer part of the reef remains close to sea level thanks to biotic growth, while the inner part of the reef falls back and becomes a lagoon as conditions are less favorable for corals and calcareous algae responsible for most of the reef`s growth. Over time, subsidence carries the ancient volcano below the surface of the sea and the coral reef remains. At this point, the island became an atoll. We must have groaned when we heard Dorothy`s bad pun.

Of course, if you are not familiar with geography, then their mind might have gone directly over your head. That`s a good question! We encourage you to take a little miracle trip to find out more, Damian. Let us know what comes to mind! The remains of an ancient atoll as a hill in a limestone area are called reef hills. The second largest atoll by land area is Aldabra, with 155 km2 (60 square miles). The largest atoll in terms of number of islands is Huvadhu Atoll in the southern Maldives with 255 islands. Bermuda is sometimes referred to as the “northernmost atoll” at a latitude of 32°18′ N. At this latitude, coral reefs would not thrive without warming waters of the Gulf Stream. However, Bermuda is called a pseudo-atoll because its general shape, although similar to that of an atoll, has a very different formation origin. Local newspaper HaveeryOnline reports that the royal couple will spend their holidays at a resort in Noonu Atoll.

The isolated atolls of the Pacific and Indian Oceans were used by the US, British and French militaries in the 20th century to test their nuclear weapons. The Soviet Union, which also possessed a nuclear arsenal, did not test the tropical atolls of the Pacific. The Soviet Union tested most of its nuclear weapons in the remote Novaya Zemlya archipelago in Russia`s Arctic. Subscribe to America`s largest dictionary and get thousands of other definitions and an advanced search – ad-free! The research of A. W. Droxler and others[5] support the previous karst model because they found that the morphology of modern atolls is independent of any influence of an underlying submerged and buried island and is not rooted in an initial fringing reef/barrier reef attached to a slow-flowing volcanic building. In fact, the neogenic reefs that underlie the modern atolls studied, and that completely bury the flattened island, are all non-atoll reefs, shallow reefs. In fact, they found that the atolls only formed after MIS-11, Mid-Brunhes, long after the many ancient islands of the Neogene were completely flooded and buried by shallow reefs. Some atolls are also famous for another reason. Their isolation and devastation make them attractive locations for nuclear weapons testing, as countries like the United States, Britain and France have done repeatedly over the past century.

Dorothy: This place can really invade you after a while! Eventually, over time, ocean waves begin to break parts of the coral reef. The pieces of coral are eroded into tiny grains of sand that accumulate on the reef to form tiny islands or a ring-shaped island. Examples of atolls are the islands of Maldives, Polynesia and Micronesia. “Atoll.” Merriam-Webster.com Dictionary, Merriam-Webster, www.merriam-webster.com/dictionary/atoll. Retrieved 2 October 2022. The origin of atolls has always fascinated sailors and naturalists, who recognized early on that although reef-building organisms inhabit only the shallowest depths of the ocean (about 100 meters [330 feet]), reefs have risen much deeper. The modern explanation of the atolls includes the theory of Charles Darwin, who proposed that the atolls represented the final stage of a sustained reef awakening around an extinct sinking volcanic island that had long since disappeared from view. For example, the United States tested the first hydrogen bomb on Bikini Atoll, which is part of the Marshall Islands in the Pacific Ocean.

Between 1947 and 1962, the United States tested more than 100 nuclear weapons on Pacific proving grounds, a series of more than 2,000 atolls and other small islands. Some of these areas are still too radioactive to be inhabited today. For those who prefer to experience the natural wonders of the atoll from the surface, Turneffe Flats offers the Adventure Atoll program, which combines snorkeling, kayaking and shore excursions to better understand the region`s ecosystems. The rocky or sandy coasts of the atolls have been important places throughout human history. Often, their low elevation has proven dangerous. Atolls are often obscured by ocean waves. Thousands of ships, from ancient Polynesian canoes to sophisticated American warships, are stranded and destroyed on hidden atolls. The Kon-Tiki, probably the most famous raft in history, became one of those victims of the atoll.

The Kon-Tiki was a large balsa raft built and sailed in 1947 by explorer Thor Heyerdahl and his crew. The Kon-Tiki successfully sailed 6,980 kilometers (4,340 miles) from Peru to the South Pacific. The hardest challenge of the trip was not the waves, currents or trade winds of the ocean. It was the atolls of Polynesia, the last part of their journey. Rapid currents around the atolls prevented the Kon-Tiki from landing on the first Polynesian island it encountered. It destroyed the shallow corals of the second, the atoll of Raroia. Raroia was uninhabited, but the nearby islanders in canoes eventually rescued the Europeans from the stranded wreck. The Kon-Tiki was eventually removed from Raroia, but atoll wrecks are popular dive sites throughout the Pacific. Shipwrecks from the 18th century to World War II lie at the foot of atolls such as Kwajalein, part of the Marshall Islands.Atolls are often uninhabited “solitary” islands. (The desert does not refer to the climate of the islands, but to their “abandoned” or uninhabited status.) Many are remote and difficult to access. This isolation did so in the 20th century. It is a testing ground for nuclear weapons from the United States, Britain and France.

The first hydrogen bomb, for example, was tested by the United States on Bikini Atoll, which is part of the Marshall Islands in the Pacific Ocean. The Pacific Proving Grounds, a series of 2,000 atolls and other islands under U.S. jurisdiction, was the site of more than a hundred massive nuclear explosions between 1947 and 1962. The France continued its nuclear tests on Moruroa Atoll until 1995. Polynesian countries, including New Zealand`s “nuclear-weapon-free zone,” have protested the intensive nuclear tests. Reefs were destroyed and some tests dropped toxic fallout on nearby inhabited islands. After Castle Bravo, the first hydrogen bomb test, the United States evacuated residents of the Rongelap and Rongerik atolls and then compensated them for illnesses associated with radiation poisoning.