Christian Leopold von Buch (26 April 1774 – 4 March 1853), usually cited as Leopold von Buch , was a German geologist and paleontologist born in Stolpe an der Oder (now a part of Angermünde , Brandenburg ) and is remembered as one of the most important contributors to geology in the first half of the nineteenth century. His scientific interest was devoted to a broad spectrum of geological topics: volcanism , petrology , fossils , stratigraphy and mountain formation . His most remembered accomplishment is the scientific definition of the Jurassic system .
43-519: Ikeda Caldera ( 池田カルデラ , Ikeda karudera ) , is a volcanic caldera filled now with Lake Ikeda and associated with the older Ata Caldera on the Satsuma Peninsula . The Ikeda volcano produced about 20,000 years before present the Iwamoto tephra layer found right around the region of Kagoshima Bay but not further. It later erupted Senta lava before about 7300 years ago erupting
86-409: A caldera, possibly an ash-flow caldera. The volcanic activity of Mars is concentrated in two major provinces: Tharsis and Elysium . Each province contains a series of giant shield volcanoes that are similar to what we see on Earth and likely are the result of mantle hot spots . The surfaces are dominated by lava flows, and all have one or more collapse calderas. Mars has the tallest volcano in
129-400: A diameter of 290 km (180 mi). The average caldera diameter on Mars is 48 km (30 mi), smaller than Venus. Calderas on Earth are the smallest of all planetary bodies and vary from 1.6–80 km (1–50 mi) as a maximum. The Moon has an outer shell of low-density crystalline rock that is a few hundred kilometers thick, which formed due to a rapid creation. The craters of
172-471: A magma chamber whose magma is rich in silica . Silica-rich magma has a high viscosity , and therefore does not flow easily like basalt . The magma typically also contains a large amount of dissolved gases, up to 7 wt% for the most silica-rich magmas. When the magma approaches the surface of the Earth, the drop in confining pressure causes the trapped gases to rapidly bubble out of the magma, fragmenting
215-601: A noticeable drop in temperature around the world. Large calderas may have even greater effects. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia . At some points in geological time , rhyolitic calderas have appeared in distinct clusters. The remnants of such clusters may be found in places such as the Eocene Rum Complex of Scotland,
258-612: A regular course of study on the production and activity of volcanoes. This is attested by his standard work on the subject entitled Physical Description of the Canary Isles (1825). His observations convinced him that these and other islands of the Atlantic owed their existence to volcanic action of the most intense kind, whereas the groups of islands in the South Sea were the remains of a pre-existing continent. During his time in
301-573: A staff in his hand, and the large pockets of his overcoat filled with papers and geological instruments. In the third edition of his On the Origin of Species published in 1861, Charles Darwin added a Historical Sketch giving due credit to naturalists who had preceded him in publishing the opinion that species undergo modification, and that the existing forms of life have descended by true generation from pre-existing forms. According to Darwin: Evolutionary biologist Ernst Mayr has written that Buch
344-560: A very advanced age: eight months before his death he visited the mountains of Auvergne, and on returning home he read a paper on the Jurassic formation before the Academy of Berlin. Humboldt, who had known him intimately for a period of more than sixty years, called him the greatest geologist of that period. Buch was unmarried and lived aloof from the world, entirely devoted to scientific pursuits. His excursions were always taken on foot, with
387-410: Is a large cauldron -like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption . An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such a chamber, greatly diminishing its capacity to support its own roof, and any substrate or rock resting above. The ground surface then collapses into
430-405: Is ejected, the emptied chamber is unable to support the weight of the volcanic edifice above it. A roughly circular fracture , the "ring fault", develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are also known as ring dikes . Secondary volcanic vents may form above the ring fracture. As the magma chamber empties, the center of the volcano within
473-625: Is heated by solid flexing due to the tidal influence of Jupiter and Io's orbital resonance with neighboring large moons Europa and Ganymede , which keep its orbit slightly eccentric . Unlike any of the planets mentioned, Io is continuously volcanically active. For example, the NASA Voyager 1 and Voyager 2 spacecraft detected nine erupting volcanoes while passing Io in 1979. Io has many calderas with diameters tens of kilometers across. Leopold von Buch Buch studied with Alexander von Humboldt under Abraham Gottlob Werner at
SECTION 10
#1732794328244516-540: Is relatively young (1.25 million years old) and unusually well preserved, and it remains one of the best studied examples of a resurgent caldera. The ash flow tuffs of the Valles caldera, such as the Bandelier Tuff , were among the first to be thoroughly characterized. About 74,000 years ago, this Indonesian volcano released about 2,800 cubic kilometres (670 cu mi) dense-rock equivalent of ejecta. This
559-508: The San Juan Mountains of Colorado , where the 5,000 cubic kilometres (1,200 cu mi) Fish Canyon Tuff was blasted out in eruptions about 27.8 million years ago. The caldera produced by such eruptions is typically filled in with tuff, rhyolite , and other igneous rocks . The caldera is surrounded by an outflow sheet of ash flow tuff (also called an ash flow sheet ). If magma continues to be injected into
602-529: The erratic blocks on the North German plains must have come from Scandinavia. He also established the fact that the whole of Sweden is slowly but continuously rising above the level of the sea from Frederikshald to Åbo . In 1815 Buch visited the Canary Islands in company with Christen Smith , a Norwegian botanist. These volcanic isles furnished the starting point from which Buch commenced
645-577: The mining school in Freiberg, Saxony . He afterwards completed his education at the universities of Halle and Göttingen . He began writing on geological topics early in life. His Versuch einer mineralogischen Beschreibung von Landeck (Breslau, 1797) was translated into French (Paris, 1805), and into English as Attempt at a Mineralogical Description of Landeck (Edinburgh, 1810). In 1802 he published Entwurf einer geognostischen Beschreibung von Schlesien ("The Geognosy of Silesia "), which became
688-899: The Canary Islands, he visited the Las Cañadas Caldera on Tenerife and the Caldera de Taburiente on La Palma. When he published his memoirs and observations about his excursion, he introduced the Spanish word "Caldera" (meaning " Bowl ") into the geological and scientific vocabulary. After his return from the Canaries he visited the basaltic group of the Hebrides and the coasts of Scotland and Ireland . Buch's geological excursions, even in countries which he had repeatedly visited before, continued without interruption until
731-417: The Earth's volcanic activity (the other 40% is attributed to hotspot volcanism). Caldera structure is similar on all of these planetary bodies, though the size varies considerably. The average caldera diameter on Venus is 68 km (42 mi). The average caldera diameter on Io is close to 40 km (25 mi), and the mode is 6 km (3.7 mi); Tvashtar Paterae is likely the largest caldera with
774-620: The English term cauldron is also used, though in more recent work the term cauldron refers to a caldera that has been deeply eroded to expose the beds under the caldera floor. The term caldera was introduced into the geological vocabulary by the German geologist Leopold von Buch when he published his memoirs of his 1815 visit to the Canary Islands , where he first saw the Las Cañadas caldera on Tenerife , with Mount Teide dominating
817-607: The Kikai-Akahoya tephra. The caldera-forming eruptions began 6400 years ago involving by the time they had finished about 5 km (1.2 cu mi) of magma and produced local pyroclastic deposits and the Ikezaki tephra. In subsequent magmatic eruptions fall deposits were created of Osagari and Mizusako scoria and Ikeda pumice . The present caldera was formed 4800 years ago when the Ikeda ignimbrite erupted that reached
860-514: The Moon have been well preserved through time and were once thought to have been the result of extreme volcanic activity, but are currently believed to have been formed by meteorites, nearly all of which took place in the first few hundred million years after the Moon formed. Around 500 million years afterward, the Moon's mantle was able to be extensively melted due to the decay of radioactive elements. Massive basaltic eruptions took place generally at
903-678: The San Juan Mountains of Colorado (formed during the Oligocene , Miocene , and Pliocene epochs) or the Saint Francois Mountain Range of Missouri (erupted during the Proterozoic eon). For their 1968 paper that first introduced the concept of a resurgent caldera to geology, R.L. Smith and R.A. Bailey chose the Valles caldera as their model. Although the Valles caldera is not unusually large, it
SECTION 20
#1732794328244946-726: The Solar System, Olympus Mons , which is more than three times the height of Mount Everest, with a diameter of 520 km (323 miles). The summit of the mountain has six nested calderas. Because there is no plate tectonics on Venus , heat is mainly lost by conduction through the lithosphere . This causes enormous lava flows, accounting for 80% of Venus' surface area. Many of the mountains are large shield volcanoes that range in size from 150–400 km (95–250 mi) in diameter and 2–4 km (1.2–2.5 mi) high. More than 80 of these large shield volcanoes have summit calderas averaging 60 km (37 mi) across. Io, unusually,
989-411: The base of large impact craters. Also, eruptions may have taken place due to a magma reservoir at the base of the crust. This forms a dome, possibly the same morphology of a shield volcano where calderas universally are known to form. Although caldera-like structures are rare on the Moon, they are not completely absent. The Compton-Belkovich Volcanic Complex on the far side of the Moon is thought to be
1032-587: The caldera atop Fernandina Island collapsed in 1968 when parts of the caldera floor dropped 350 metres (1,150 ft). Since the early 1960s, it has been known that volcanism has occurred on other planets and moons in the Solar System . Through the use of crewed and uncrewed spacecraft, volcanism has been discovered on Venus , Mars , the Moon , and Io , a satellite of Jupiter . None of these worlds have plate tectonics , which contributes approximately 60% of
1075-676: The collapsed magma chamber, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at the Valles Caldera , Lake Toba , the San Juan volcanic field, Cerro Galán , Yellowstone , and many other calderas. Because a silicic caldera may erupt hundreds or even thousands of cubic kilometers of material in a single event, it can cause catastrophic environmental effects. Even small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction and
1118-567: The eastern and western sides and southern tip of the Satsuma Peninsula . The north western wall of this caldera aligns with the Onkadobira fault scarp. This was followed by later eruptions including the Ikedako tephra and those from a fissure vent line southeast of the caldera that produced the pumiceous Yamagawa base surge. A central lava dome was formed within the caldera during the late stage of these eruptions. About 2,800 years ago on part of
1161-403: The emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater , the feature is actually a type of sinkhole , as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur over the course of a century,
1204-465: The first volume of his Geognostische Beobachtungen auf Reisen durch Deutschland und Italien ("Geognistic Observations while Travelling through Germany and Italy", see below). He was at this time a zealous upholder of the Neptunian theory of Werner, with some modifications. In 1797, he met Humboldt at Salzburg , and with him explored the geological formations of Styria , and the adjoining Alps . In
1247-464: The formation of a caldera is a rare event, occurring only a few times within a given window of 100 years. Only eight caldera-forming collapses are known to have occurred between 1911 and 2018, with a caldera collapse at Kīlauea , Hawaii in 2018. Volcanoes that have formed a caldera are sometimes described as "caldera volcanoes". The term caldera comes from Spanish caldera , and Latin caldaria , meaning "cooking pot". In some texts
1290-467: The human species was reduced to approximately 5,000–10,000 people. There is no direct evidence, however, that either theory is correct, and there is no evidence for any other animal decline or extinction, even in environmentally sensitive species. There is evidence that human habitation continued in India after the eruption. Some volcanoes, such as the large shield volcanoes Kīlauea and Mauna Loa on
1333-429: The island of Hawaii , form calderas in a different fashion. The magma feeding these volcanoes is basalt , which is silica poor. As a result, the magma is much less viscous than the magma of a rhyolitic volcano, and the magma chamber is drained by large lava flows rather than by explosive events. The resulting calderas are also known as subsidence calderas and can form more gradually than explosive calderas. For instance,
Ikeda Caldera - Misplaced Pages Continue
1376-430: The landscape, and then the Caldera de Taburiente on La Palma . A collapse is triggered by the emptying of the magma chamber beneath the volcano, sometimes as the result of a large explosive volcanic eruption (see Tambora in 1815), but also during effusive eruptions on the flanks of a volcano (see Piton de la Fournaise in 2007) or in a connected fissure system (see Bárðarbunga in 2014–2015). If enough magma
1419-561: The magma to produce a mixture of volcanic ash and other tephra with the very hot gases. The mixture of ash and volcanic gases initially rises into the atmosphere as an eruption column . However, as the volume of erupted material increases, the eruption column is unable to entrain enough air to remain buoyant, and the eruption column collapses into a tephra fountain that falls back to the surface to form pyroclastic flows . Eruptions of this type can spread ash over vast areas, so that ash flow tuffs emplaced by silicic caldera eruptions are
1462-460: The margin of the caldera rim the andesitic Nabeshimadake lava dome was formed. During the caldera forming events, and after, about 2.5 km (0.60 cu mi) of ignimbrite and 7 km (1.7 cu mi) of tephra was erupted with each of the tephra deposits reaching into the Ōsumi Peninsula due to the prevailing winds. Ikeda Caldera is associated in the Ibusuki volcanic field with
1505-585: The more recently active Kaimondake stratovolcano . The National Catalogue of the Active Volcanoes of Japan (JMA, 2013) includes features of the Ibusuki volcanic field as part of the Ata post-caldera system. This Kagoshima Prefecture location article is a stub . You can help Misplaced Pages by expanding it . Caldera A caldera ( / k ɔː l ˈ d ɛr ə , k æ l -/ kawl- DERR -ə, kal- )
1548-476: The only volcanic product with volumes rivaling those of flood basalts . For example, when Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km of material (as measured in dense rock equivalent (DRE)), covering a substantial part of North America in up to two metres of debris. Eruptions forming even larger calderas are known, such as the La Garita Caldera in
1591-462: The ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. The total area that collapses may be hundreds of square kilometers. Some calderas are known to host rich ore deposits . Metal-rich fluids can circulate through the caldera, forming hydrothermal ore deposits of metals such as lead, silver, gold, mercury, lithium, and uranium. One of
1634-530: The spring of 1798, Buch extended his excursions into Italy , where his faith in the Neptunian theory was shaken. In his early works, he had advocated the aqueous origin of basaltic and other formations, but now he saw cause to abandon Werner's theory, and to recognize the volcanic origin of the basalts . He saw Vesuvius for the first time in 1799. Later, in 1805, he had the opportunity, along with Humboldt and Gay Lussac , of witnessing its actual eruption. It
1677-502: The world in the two volumes of his Geognostische Beobachtungen (Berlin, 1802 and 1809). In 1806, Buch proceeded to Scandinavia and spent two years in examining its physical constitution. This furnished the materials for his work entitled Reise durch Norwegen und Lappland ("Travels in Norway and Lapland", Berlin, 1810). He made many important observations on the geography of plants, on climatology and on geology. He showed that many of
1720-653: The world's best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario , Canada, which formed during the Neoarchean era about 2.7 billion years ago. In the San Juan volcanic field , ore veins were emplaced in fractures associated with several calderas, with the greatest mineralization taking place near the youngest and most silicic intrusions associated with each caldera. Explosive caldera eruptions are produced by
1763-501: Was a remarkable eruption, and supplied Buch with data for refuting many erroneous ideas then entertained regarding volcanoes. In 1802 he examined the extinct volcanoes of Auvergne in the south of France . The aspect of the Puy de Dôme , with its cone of trachyte and its strata of basaltic lava, induced him to abandon as untenable the doctrines of Werner on the formation of these rocks. The results of all these geological travels were given to
Ikeda Caldera - Misplaced Pages Continue
1806-749: Was the first naturalist to suggest geographic speciation , in 1825. In 1825, he was elected a foreign member of the Royal Swedish Academy of Sciences . Buch was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1849. Recipient of the Pour le Mérite for Sciences and Arts. Elected as the first foreign member of the Geological Society of London . The German Geological Society (DGG) named its Leopold-von-Buch-Plakette after him. Besides
1849-464: Was the largest known eruption during the ongoing Quaternary period (the last 2.6 million years) and the largest known explosive eruption during the last 25 million years. In the late 1990s, anthropologist Stanley Ambrose proposed that a volcanic winter induced by this eruption reduced the human population to about 2,000–20,000 individuals, resulting in a population bottleneck . More recently, Lynn Jorde and Henry Harpending proposed that
#243756