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High Island
Geologically, a volcanic island is an island of volcanic origin. The term high island can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed on sunken volcanoes). Definition and origin There are a number of volcanic islands that rise no more than above sea level, often classified as islets or rocks, while some low islands, such as Banaba, Henderson Island, Makatea, Nauru, and Niue, rise over above sea level. The two types of islands are often found in proximity to each other, especially among the islands of the South Pacific Ocean, where low islands are found on the fringing reefs that surround most volcanic islands. Volcanic islands normally rise above a hotspot or subduction zone. Habitability Volcanic islands usually range in size between . Islands above a certain size usually have fresh groundwater, while low islands often do not, so volcanic islands are more likely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Banaba
BanabaThe correct spelling and etymology in Gilbertese should be ''Bwanaba'' but the Constitution of Kiribati writes Banaba. Because of the spelling in English or French, the name was very often written Paanapa or Paanopa, as it was in 1901 Act. (; formerly Ocean Island) is an island of Kiribati in the Pacific Ocean. A solitary raised coral island west of the Gilbert Island Chain, it is the westernmost point of Kiribati, lying east of Nauru, which is also its nearest neighbour. It has an area of , and the highest point on the island is also the highest point in Kiribati, at in height. Along with Nauru and Makatea (French Polynesia), it is one of the important elevated phosphate-rich islands of the Pacific. History According to ''Te Rii ni Banaba (The Backbone of Banaba)'' by Raobeia Ken Sigrah, Banaban oral history supports the claim that the people of the Te Aka clan, which originated in Melanesia, were the original inhabitants of Banaba, having arrived before the arri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures is Scientific consensus on climate change, driven by human activities, especially fossil fuel burning since the Industrial Revolution. Fossil fuel use, Deforestation and climate change, deforestation, and some Greenhouse gas emissions from agriculture, agricultural and Environmental impact of concrete, industrial practices release greenhouse gases. These gases greenhouse effect, absorb some of the heat that the Earth Thermal radiation, radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary gas driving global warming, Carbon dioxide in Earth's atmosphere, has increased in concentratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groundwater
Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit of rock or an unconsolidated deposit is called an ''aquifer'' when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the ''water table''. Groundwater is Groundwater recharge, recharged from the surface; it may discharge from the surface naturally at spring (hydrosphere), springs and Seep (hydrology), seeps, and can form oasis, oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction water well, wells. The study of the distribution and movement of groundwater is ''hydrogeology'', also called groundwater hydrology. Typically, groundwater is thought o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction Zone
Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. Subduction is possible because the cold and rigid oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle. Once initiated, stable subduction is driven mostly by the negative buoyancy of the dense subducting lithosphere. The down-going slab sinks into the mantle largely under its own ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hotspot (geology)
In geology, hotspots (or hot spots) are volcanic locales thought to be fed by underlying Mantle (geology), mantle that is anomalously hot compared with the surrounding mantle. Examples include the Hawaii hotspot, Hawaii, Iceland hotspot, Iceland, and Yellowstone hotspots. A hotspot's position on the Earth's surface is independent of plate boundary, tectonic plate boundaries, and so hotspots may create a chain of volcanoes as the plates move above them. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The alternative plate theory (volcanism), plate theory is that the mantle source beneath a hotspot is not anomalously hot, rather the crust above is unusually weak or thin, so that lithospheric extension permits the passive rising of melt from shallow depths. Origin The origins of the concept of hotspots lie in the work of J. Tuzo Wilson, who postulated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fringing Reef
A fringing reef is one of the three main types of coral reef. It is distinguished from the other main types, barrier reefs and atolls, in that it has either an entirely shallow backreef zone (lagoon) or none at all. If a fringing reef grows directly from the shoreline, then the reef flat extends to the beach and there is no backreef. In other cases (e.g., most of the Bahamas), fringing reefs may grow hundreds of yards from shore and contain extensive backreef areas within which it contains food and water. Some examples of this are Philippines, Indonesia, Timor-Leste, the western coast of Australia, the Caribbean, East Africa, and Red Sea. Charles Darwin believed that fringing reefs are the first kind of reefs to form around a landmass in a long-term reef growth process.Kennedy, D.M. and Woodroffe, C.D. 2002.Fringing reef growth and morphology: a review. ''Earth-Science Reviews''. 57:255-277. The largest fringing coral reef in the world is the Ningaloo Reef, stretching to around ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Islands In The Pacific Ocean
The Pacific islands are a group of islands in the Pacific Ocean. They are further categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term ''Pacific Islands'' may refer to one of several concepts: (1) those countries and islands with common Austronesian peoples, Austronesian origins, (2) the islands once (or currently) colonization, colonized, (3) the geographical region of Oceania, or (4) any island located in the Pacific Ocean. This list of islands in the Pacific Ocean is organized by archipelago or border, political boundary. In order to keep this list of moderate size, the more complete lists for countries with large numbers of small or uninhabited islands have been hyperlinked. Name ambiguity and groupings The umbrella term ''Pacific Islands'' has taken on several meanings. Sometimes it is used to refer only to the islands defined as lying within Toa Samoa. At other times, it is used to refer to the islands of the Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niue
Niue is a self-governing island country in free association with New Zealand. It is situated in the South Pacific Ocean and is part of Polynesia, and predominantly inhabited by Polynesians. One of the world's largest coral islands, Niue is commonly referred to as "The Rock", which comes from the traditional name "Rock of Polynesia". Niue's position is inside a triangle drawn between Tonga, Samoa, and the Cook Islands. It is northeast of New Zealand, and northeast of Tonga. Niue's land area is about and its population was 1,689 at the Census in 2022. The terrain of the island has two noticeable levels. The higher level is made up of a limestone cliff running along the coast, with a plateau in the centre of the island reaching approximately above sea level. The lower level is a coastal terrace approximately 0.5 km (0.3 miles) wide and about 25–27 metres (80–90 feet) high, which slopes down and meets the sea in small cliffs. A coral reef surrounds the island; the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nauru
Nauru, officially the Republic of Nauru, formerly known as Pleasant Island, is an island country and microstate in the South Pacific Ocean. It lies within the Micronesia subregion of Oceania, with its nearest neighbour being Banaba (part of Kiribati) about to the east. With an area of only , Nauru is the List of countries and dependencies by area, third-smallest country in the world, larger than only Vatican City and Monaco, making it the smallest republic and island nation, as well as the smallest member state of the Commonwealth of Nations by area. Demographics of Nauru, Its population of about 10,800 is the world's List of countries and dependencies by population, third-smallest (not including colonies or overseas territories). Nauru is a member of the United Nations, the Commonwealth of Nations, and the Organisation of African, Caribbean and Pacific States. Settled by Micronesians circa 1000 Common Era, BCE, Nauru was annexation, annexed and claimed as a colony by the G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Makatea
Makatea, or Mangaia-te-vai-tamae, is a raised coral atoll in the northwestern part of the Tuamotus, which is a part of the French overseas collectivity of French Polynesia. It is located southwest from Rangiroa to the west of the Palliser Islands, Palliser group, which also is in French Polynesia. Makatea is surrounded by spectacular cliffs, rising to a plateau above sea level. This island is long, with a maximum width of in the south. It is in area. Makatea is one of only four islands of the Tuamotus, Tuamotu Archipelago (along with filled atolls Nukutavake, Tikei, and Tepoto (North), Tepoto Nord) that do not take the form of a typical atoll. History Makatea is one of the only Paumotuan islands with Drinking water, potable water. Its native name derived from the drinking water being brought out of its dark caves by the local people. "Mā," pure, clear; used here to mean water, "Atea," light of day and "K" for euphony. The other name of the Island was Mangaia-te-vai-tamāe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henderson Island (Pitcairn Islands)
Henderson Island is an uninhabited island in the south Pacific Ocean. It is part of the Pitcairn Islands, Pitcairn Island Group, together with Pitcairn Island, Pitcairn, Oeno Island, Oeno, and Ducie Island, Ducie Islands. Measuring , it has an area of and is located northeast of Pitcairn Island, which is the only inhabited island of the group. It has poor soil and little fresh water, and is unsuitable for agriculture. There are three beaches on the northern end and the remaining coast comprises steep (mostly undercut) cliffs up to in height. In 1902, it was annexed to the Pitcairn Islands colony, which is now a British Overseas Territories, British Overseas Territory. Henderson is one of the last two raised coral atolls in the world whose ecosystems remain relatively unaffected by human contact, along with Aldabra in the Indian Ocean. In 1988, it was designated a World Heritage Site by the United Nations. Ten of its 51 flowering plants, all four of its land birds and about a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
