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Harker Point
Bristol Island is an uninhabited island in the South Sandwich Islands, an archipelago in the Southern Ocean. The island is almost entirely surrounded by ice cliffs and largely covered with ice. It features both the oldest rocks of this archipelago and an active volcano that last erupted in 2016. Geography and geomorphology Bristol Island is one of the South Sandwich Islands, which lie southeast of South Georgia in the Southern Ocean and extend over a distance of in a north–south direction. It lies about southwest of Montagu Island and is separated from Southern Thule by Forsters Passage. The first island of the South Sandwich Islands to be discovered was Freezland Rock, which was sighted on 31 January 1775 by a sailor named Freezland on James Cook's HMS ''Resolution''. Cook considered Bristol Island to be a promontory on a larger island; it was Thaddeus von Bellingshausen who in 1819 determined that Bristol was actually an island. The island is almost inaccessible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Sandwich Islands
The South Sandwich Islands () are a chain of uninhabited volcanic islands in the South Atlantic Ocean. They are administered as part of the British Overseas Territory of South Georgia and the South Sandwich Islands. The chain lies in the sub-Antarctic region, about southeast of South Georgia and northeast from the tip of the Antarctic Peninsula. The archipelago comprises 11 main islands forming an island arc running north–south, the largest being Montagu at . It is divided into four groups, from north to south: The Traversay, Candlemas and Central Islands ( Saunders, Montagu, and Bristol), and Southern Thule. The archipelago is prone to violent earthquakes. Over the previous century, nine M 7+ earthquakes have occurred here, the most recent being the M 8.1 in August 2021. None of these earthquakes are known to have caused fatalities due to their remote location. History The southern eight islands of the South Sandwich Islands were discovered by Captain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Stack
A stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion. Stacks are formed over time by wind and water, processes of coastal geomorphology. britannica.com They are formed when part of a is by hydraulic action, which is the force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vindication Island
Vindication Island is a small uninhabited island of the Candlemas Islands in the South Sandwich Islands. It is one of about a dozen islands that make up the South Sandwich island arc, a chain of volcanoes in the Southern Ocean that was discovered in 1775 by James Cook. The volcanism is caused by the subduction of the South American Plate beneath the Sandwich Plate. The island has a rectangular outline and is the remnant of three mostly eroded volcanoes. The highest point of the island, Quadrant Peak, directly overlies the coast. Inland Vindication Island features a rich vegetation, consisting of lichens and mosses, while various bird and penguin species breed along the coasts. There is no evidence of recent volcanic activity. History and toponymy Vindication and Candlemas Island were both discovered on 2 February 1775 by James Cook aboard . In 1951–1952 the Argentine frigates and installed a marker on Vindication, claiming Argentine sovereignty over the island; this is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candlemas Island
Candlemas Island is a small uninhabited island of the Candlemas Islands in the South Sandwich Islands. It is one of about a dozen islands that make up the South Sandwich island arc, a chain of volcanoes in the Southern Ocean that was discovered in 1775 by James Cook. The volcanism is caused by the subduction of the South American Plate beneath the Sandwich Plate. The island is remote and rarely visited due to the often hostile weather conditions, but is populated by penguins and seabirds, which form large breeding colonies. The island consists of two parts. The southeastern part is older and consists of the heavily glaciated volcanoes Mount Andromeda - with elevation the highest point of the island - and Mount Perseus, and shows no evidence of recent activity. The northwestern part features the younger scoria cone complex Lucifer Hill, which is surrounded by lava flows. Some of the lava flows may have been emplaced during the 20th century. The older rocks consist mostly of ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visokoi Island
Visokoi Island is an uninhabited volcanic island and one the three Traversay Islands that constitute a subgroup of the South Sandwich Islands, in the Southern Ocean. Visokoi consists of one major volcano, Mount Hodson, whose height is usually given as . The mountain is mostly covered by glaciers, except for several low areas on the coast like the northern Finger Point and eastern Irving Point. Several parasitic vents are found especially on the eastern side, and one vent close to Finger Point is still hot. Eruptions were reported in 1830, 1927 and 1930, and a large landslide took place during historical time. Geography and geomorphology Visokoi is one of the South Sandwich Islands, which lie southeast of South Georgia in the Southern Ocean and extend over a distance of in north-south direction. Leskov Island is west and Zavodovski Island north from Visokoi; together they makes up the Traversay Islands subgroup of the South Sandwich Islands. Icebergs occur in the surroun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leskov Island
Leskov Island is one of the three Traversay Islands that form a subgroup of the South Sandwich Islands, in the Southern Ocean. The island is named after Russian sailor Arcady Leskov. It is a semicircular high eroded volcano with a large bay on its eastern side. Leskov Island is almost entirely surrounded by cliffs and has a surface area of . Volcanic rocks form tuffs and lava and consist almost entirely of andesite. There are no known historical eruptions, but there is widespread fumarolic activity which has varied over time. Mosses and liverworts grow next to the fumaroles, but this vegetation also occurs away from the vents. Several seabirds have been observed nesting on the island. Geography and geomorphology The South Sandwich Islands in the Southern Ocean, which include Leskov Island, lie at the eastern margin of the Scotia Sea and were discovered in 1775 by James Cook. The islands have had little human presence, with only sporadic research efforts during the 20th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zavodovski Island
Zavodovski Island is an uninhabited volcanic island in the Traversay Islands subgroup of the South Sandwich Islands, which are located southeast of South Georgia in the South Atlantic Ocean. Zavodovski is the northernmost of the South Sandwich Islands and consists of one major stratovolcano, Mount Curry, which is surrounded to the east by a plain formed by lava flows. Mount Curry has a fumarolically active crater on the southwestern side, which also bears traces of a sector collapse. An eruption occurred in 2016. The island was officially discovered in December 1819 by Thaddeus von Bellingshausen. The largest penguin colony on Earth with over a million breeding pairs is situated on Zavodovski. It consists mostly of chinstrap penguins, although other seabirds and penguin species breed on the island as well. Early explorers noted the bad smell of the island, which is reflected in numerous placenames. Geography and geomorphology Zavodovski is the northernmost of the South ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kemp Caldera
Kemp Caldera and Kemp Seamount form a submarine volcano south of the South Sandwich Islands, in a region where several seamounts are located. The seamount rises to a depth of below sea level; the caldera has a diameter of and reaches a depth of . The caldera contains several Hydrothermal vents, including white smokers (a type of vent that emits cold, alkaline fluids) and diffuse venting areas, which are host to chemolithotrophic ecological communities. The seamount and caldera, which were discovered by seafloor mapping in 2009, are part of the South Georgia and the South Sandwich Islands Marine Protected Area. Geography and geomorphology Kemp Caldera lies at the southern end of the South Sandwich Islands, between the Scotia Sea to the north and the Weddell Sea to the south, about west-southwest of Thule Island. The caldera was discovered and sampled in 2009 during bathymetric mapping operations carried out by the . Further sampling efforts took place in 2010 and 2011. Another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Volcano
Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. Many submarine volcanoes are located near areas of tectonic plate formation, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth.Martin R. Speight, Peter A. Henderson, "Marine Ecology: Concepts and Applications", John Wiley & Sons, 2013. . Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in shallow water, and these can discharge material into the atmosphere during an eruption. The total number of submarine volcanoes is estimated to be over one million (most are now extinct) of which some 75,000 rise more than above the seabed. Only 119 submarine volcanoes in Earth's oceans and seas are known to have erupted during the last 11,700 years. Hydrothermal vents, sites of abundant biological activity, are commonly found near submarine volcanoes. Effect of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Island Arc
Island arcs are long archipelago, chains of active volcanoes with intense earthquake, seismic activity found along convergent boundary, convergent plate tectonics, tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the Earth's mantle, mantle along the subduction zone. They are the principal way by which continental growth is achieved. Island arcs can either be active or inactive based on their seismicity and presence of volcanoes. Active arcs are ridges of recent volcanoes with an associated deep seismic zone. They also possess a distinct curved form, a chain of active or recently extinct volcanoes, a oceanic trench, deep-sea trench, and a large negative Bouguer anomaly on the convex side of the volcanic arc. The small positive gravity anomaly associated with volcanic arcs has been interpreted by many authors as due to the presence of dense volcanic rocks beneath the arc. Inactive arcs are a chain of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduct
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 weigh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
