Misplaced Pages

#842157

96-500: Hohentwiel is a mountain of volcanic origin in the Hegau region of Baden-Württemberg in southern Germany . It is the Hausberg of the industrial city of Singen , located west of it and ca 10 km (6.2 mi) west of Zeller See ( Lake Constance ). The ruins of the medieval Hohentwiel Castle rest on top of it. Hohentwiel was an active volcano about 7–8 million years ago during

192-663: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. Swabian Jura The Swabian Jura occupies the region bounded by the Danube in the southeast and the upper Neckar in the northwest. In the southwest it rises to the higher mountains of the Black Forest . The highest mountain in the region is the Lemberg (1,015 m (3,330 ft)). The area's profile resembles

288-496: A karst landscape, featuring subterranean rivers which flow through a large system of caves before they emerge. As a result there are hardly any rivers, lakes or other forms of surface water on the plateau. In some places, former volcanic activity has left traces, such as maars and hills. In the west, the Zollerngraben (a geological depression in a tectonically active region) sometimes causes mild earthquakes. The Nördlinger Ries

384-476: A magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas

480-482: A "luxury outlet town", with people from all over Europe coming to buy expensive clothes cheaper). From this, machine building and advanced engineering developed. With the invention of cars and the founding of Daimler-Benz nearby, the car industry and later also electronics and computer industries developed. The " Neckar-Alb " region is the third largest industrial zone in Germany, and the most stable. The best known company

576-401: A duration of 6-7 million years. The time span can be divided into two sections. In the first three million years, eruptions of volcanoes such as Ur-Hohentwiel reached the earth's surface, creating a tuff cone mountain which towered over its surroundings by 100-200 metres. In the course of time and with a decrease in eruptions, the thickness of the covering tuffs reduced due to erosion. During

672-401: A few kilometers apart, some of the oldest signs of human artifacts were found. Best known are: a mammoth, a horse head, a water bird, and two statues of a lion man all of surprising quality and all more than 30,000 years old. The oldest known musical instruments have been found here, too: flutes made from the bones of swans and griffon vultures, some 35,000 years old, and in 2004

768-613: A flute carved from the tusk of a mammoth dating from the Ice Age, around 37,000 years ago, and the oldest representation of the human body, the Venus of Schelklingen . This region, located south of the limes , was part of the Roman Empire from around the first to third century A.D. A Roman road ran along the Neckar river and over the plateau. In Hechingen-Stein a Roman outpost along this road

864-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,

960-512: A high plateau, which slowly falls away to the southeast. The northwestern edge is a steep escarpment (called the Albtrauf or Albanstieg, rising up 400 m (1,300 ft), covered with forests), while the top is flat or gently rolling. In economic and cultural terms, the Swabian Jura includes regions just around the mountain range. It is a popular recreation area. The whole Schwäbische Alb area

1056-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano

SECTION 10

#1732848470843

1152-587: A proper noun referring more or less exclusively to the Swabian and the Franconian Jura ( German : Fränkische Alb ) areas however, and as such has no direct translation into most other languages. It is perhaps for this reason that Schwäbische Alb has sometimes been translated into English as 'Swabian Alps', thus avoiding the lesser-known name Jura . However, the area is not part of the Alps (despite its proximity), nor

1248-449: A small private museum, called Urwelt-Museum Hauff, provides visitors with the opportunity to "dig" for fossils in their shale deposits. The Urwelt-Museum Hauff houses the world's largest petrified crinoid (sea-lily) colony with a size of 18 m × 6 m (59 ft × 20 ft) and an age of about 180 million years. In a number of caves (including Vogelherd, Hohlenstein-Stadel , Geißenklösterle and Hohle Fels ), all just

1344-470: A stronger Fasnet tradition. A Swabian Fasnet celebration in any case has little or nothing in common with the simultaneous celebrations along the Middle Rhein, which are well known across Germany because they are televised every year. Swabians generally are expected to go to work as normal on Rose Monday and Fat Tuesday, unlike their neighbors to the northwest. Since raising crops was not easy, raising sheep

1440-493: A tributary to the Rhine . The soil is not very fertile, the humus is often as thin as 10 cm (4 in). Many small limestone pebbles are found on the surface. Much of the Swabian Jura consists of gentle to moderate hills often covered with forest or cleared for small-scale agriculture . The traditional landscape was grass fields with juniper bushes . Today this has become a comparatively rare sight. However, in certain places it

1536-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa

1632-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on

1728-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while

1824-468: Is a UNESCO global geopark covering 6,688 km (2582 sq mi.); it was designated as a National Geopark in Germany in 2002 and became a member of the European Geoparks Network in 2004; in 2015 it was included in the newly established scheme of UNESCO Global Geoparks. In its central area it comprises a Swabian Alb Biosphere Reserve of 852.69 km (330 sq. mi.). The geology of the Swabian Jura

1920-727: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in

2016-494: Is a large meteorite crater (15 million years old). Tertiary relicts can be found in the southern part of Swabian Jura. Famous locations are known in the Ulm area (e.g., Turritellenplatte of Ermingen). Constant rain and other weather influences are slowly dissolving the entire range. Each year, it recedes approximately 2 mm (0.08 in). Some millions of years ago, the mountains reached as far as Stuttgart . In some places,

SECTION 20

#1732848470843

2112-550: Is an isolated extinct volcanic mountain located in the south of Baden-Württemberg, Germany, in the Hegau region. It is part of the administrative district of Freiburg and the district of Constance. The Radolfzeller Aach tributary of the Rhine runs at the base the eastern slope of Hohentwiel, while Lake Constance is located some kilometres south-east, and the town of Hilzingen 3 km west. The extinct volcanoes Hohenkrähen , Mägdeberg and Hohenstoffeln are situated 4-6 km north-northwest of

2208-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where

2304-554: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in

2400-567: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for

2496-454: Is mostly limestone , which formed the seabed during the Jurassic period. The sea receded 50 million years ago. Three layers of different limestones are stacked over each other to form the range: Black Jurassic , Brown Jurassic , and White Jurassic . White Jurassic may be as pure as 99% calcium carbonate . Since limestone is soluble in water, rain seeps through cracks everywhere, forming

2592-524: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near

2688-654: Is protected by the government of Baden-Württemberg. The highest elevations reach just over 1,000 metres (3,300 ft). They are all in the southwestern part of the Jura, in the region of the Großer Heuberg . There are many other peaks in the Alb, such as the Hornau , Ochsenberg , and Achalm . Fossils can be found everywhere in the Swabian Jura. Many large and important fossils were found here. At Holzmaden, outside of Weilheim unter Teck,

2784-498: Is still Daimler-Benz, today known simply as Daimler AG , followed by Robert Bosch . The region has one of the highest patents-to-population ratios in the world. Many products fall into the high-tech category. The small and medium enterprise sector (100-5,000 employees) predominates. Perhaps as a result, the unemployment rate is low. In general, products are expensive but compete through high quality. Several districts are recognised as especially attractive to business, e.g. Reutlingen as

2880-466: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in

2976-600: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off

Hohentwiel - Misplaced Pages Continue

3072-618: The Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,

3168-673: The Jura mountains , of which the Swabian and Franconian plateaux are geographically part. In German, at least outside geological circles, the word Alb is used almost universally in place of Jura . The origin of the word is uncertain. One theory is that it derives form the Latin albus ("white"). Another is that it is from a pre-Indo-European word albhros ("hill"). It is related to the German words Alpe , Alm or Alp (from Old High German alpâ ), meaning an " upland pasture ". The word Alb functions as

3264-502: The Miocene epoch , along with several other volcanoes in the Hegau region. It mostly consists of phonolite , which represents the former volcanic pipe . The surrounding softer rocks have been eroded over time by ice age glaciers during the Riss glaciation , creating an inverted relief and giving the mountain its present-day shape. The first written accounts of Hohentwiel Castle are held within

3360-594: The South German Jurassic . With the beginning of the Alpine Uplift Event, which transpired approximately 65 million years ago, land rose from the sea due to the collision between the African and European continents. To compensate for the elevation of land, the area inbetween the newly formed Alps and Swabian Alb subsided, and with it, the Hegau region. This erosive processes of the subsidance caused much of

3456-824: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when

3552-490: The Alemannic-speaking region, has been the source of particular scholarly inquiry. Initial attempts to explain the etymology by Melchior Goldast pursued a Latin derivation of duellum meaning 'place where fighting [took place]' but this attribution was rejected by Ernst Förstemann in his Altdeutschen Namenbuch (Old German Name Book) of 1859 in favour of a Celtic conjecture. As Hermann Jellinghaus noted upon revisiting

3648-843: The Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which

3744-612: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like

3840-582: The Rhine Rift Valley, where the Alps were formed. A remnant of this activity is the Ur-Hohentwiel vent, which is filled with depositing tuff, as well as phonolite that rises out of the eastern terrain. During the Jurassic period (201-145 million years ago), the continental shelf of Central Europe was submerged under the primeval Tethys Ocean , resulting in sedmentation convering the area and formation of

3936-632: The Rhine glacier, eroded the molasse and tuff layers around the Hohentwiel plug, causing the mountain summit to become exposed as the ice receded. Tuff is only present in the western portion, due to the neutralising effect of the ice masses in their direction of advance. Stratification of the Hohentwiel landscape is characterised by layers of sedimentary rocks - including Brown Jurassic , White Jurassic , Kimmeridgian , Tithonian , Lower Freshwater Molasse, Brackish Molasse, Upper Seawater Molasse, Jurassic Gelfluh of

Hohentwiel - Misplaced Pages Continue

4032-556: The St. Gallen monastery chronicle of Ekkehard IV (circa A.D. 980-1060) as "castellum tuiel", which was reportedly besieged in 915. In the Late Middle Ages , the name of the castle evolved from "Tuiel" to "Twiel" and eventually moved to its current spelling of "Hohentwiel" ( lit.   ' High Twiel ' ). The earliest record of its modern iteration is recorded in 1521. Twiel , a name of varying signification which appears multiple times in

4128-508: The Tortonian period of the late Miocene, the second phase of volcanic activity took place. Rising magma no longer reached the surface land area, but solidified in ascending passages through the molasse. The composition of the magma likely had a higher silica content, causing the mass to have increased viscosity and durability. This resulted in the formation of a vent plug under the tuff layer, approximately 100 metres thick. The Quaternary period

4224-609: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in

4320-494: The Upper Freshwater Molasse, phonolite debris, cover tuff, mica sands, and Jurassic nape. These sedimentary layers range in thickness from 100 to 150 metres, with an additional 70 metres of basic facies at the lower level. This is topped by an upper layer of moraine material in the far western portion of the mountain. Hohentwiel Castle, whose ruins are on top of Hohentwiel, was built in 914 using stone taken from

4416-503: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to

4512-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down

4608-560: The discharge of the water from subterranean rivers can be spectacular, too, e.g. the Blautopf , a source for a tributary of the Danube. Also because of the porous limestone, the Danube nearly disappears near Immendingen (in 1911, 1921, 1928 and 1943 it disappeared completely), only to reappear several kilometers further down. Most of the water lost by the Danube resurfaces in the Aachtopf , a spring for

4704-772: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in

4800-671: The exact traditions vary from village to village, creating a fantastic variety of heroes, villains and good and evil creatures. It is also often the case that, while in one town a strong tradition of celebrating Fasnet has survived, the neighboring town will have almost no tradition. This is in many instances linked to the after-effects of the Protestant Reformation and the later influence of the Calvinistic Pietists, who more or less strictly opposed such frivolous - even heathen - behaviour. Catholic regions to this day tend to have

4896-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from

SECTION 50

#1732848470843

4992-494: The foreland of the Swabian Jura officially don't belong to it. There are many castles, monasteries, churches, ruins and old towns. Here is a small selection. A good way for tourists to get to know the Swabian Jura is to travel on the Schwäbische Albstraße , a "National Scenic Byway", leading from Tuttlingen or Trossingen to Nördlingen or Aalen . The name German : Jura (related to Jurassic ) derives from

5088-592: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which

5184-568: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in

5280-461: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in

5376-462: The highest rents in Germany, while land on the plateau itself is considered cheap (by south German standards). Many town names end in -ingen . There were several military training grounds, some also used by NATO troops. On the Münsingen training ground which existed for over 100 years, a biosphere reserve is in the making. The region has several larger and many small nature reserves. The towns in

5472-473: The hills are not steep or high) and numerous small resorts can be found. It is often windy and a bit colder than the rest of Germany. Because of a special micro climate, a small weather station near the town of Stetten am kalten Markt is known as the "coldest spot in Germany". The Swabian Jura are not densely populated by German standards. Most of the larger towns are outside the region, though they are often counted as part of it. These towns often have some of

5568-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include

5664-553: The limestone was more resistant to decay and thus the recession of the main range has left small mountains (called "Zeugenberge"—"witness mountains" or outliers ; e.g. the Achalm or the Hohenstaufen ) which testify to the former territory of the range. The omnipresent caves are great tourist spots, beautiful and not very crowded. Many different types can be found, from dry dripstone caves to caves that can only be entered by boat. Sometimes

5760-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of

5856-545: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius

SECTION 60

#1732848470843

5952-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of

6048-583: The mountain by Burchard II, Duke of Swabia . Originally, the Monastery of St. Georg was within the fortress, but in 1005 it was moved to Stein am Rhein (now in Switzerland ), and the Swabian dukes lost control of Hohentwiel. In the later Middle Ages the noble families von Singen-Twiel (12th–13th centuries), von Klingen (to 1300) and von Klingenberg (to 1521) resided here. In 1521, it was passed on to Duke Ulrich von Württemberg , who developed Hohentwiel into one of

6144-482: The mountain. Hohentwiel's headwaters slope steeply downward and are completely forested while its foot has flatter slopes to the west. The mountain rises approximately 260 metres out of the Aachtal Valley to the east. Hohentwiel is located in a geological unit that encompasses Hegau and the western portion of Lake Constance. Its multiple geological layers were formed through sedimentation and volcanism, as evidenced by

6240-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma

6336-411: The naming work of Förstemann in 1916, the latter suggestion was found to be "hardly Celtic", and as Twiel recurs in several areas of Switzerland , a new hypothesis was required. In recent years an Alemannic origin has been advanced, on the basis of its initial sound being suggestive of an Indo-European root ' tu ' - meaning 'swell'. Nevertheless, this interpretation remains inconclusive. Hohentwiel

6432-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of

6528-867: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio

6624-541: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by

6720-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break

6816-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb

6912-462: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as

7008-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as

7104-595: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under

7200-411: The poor quality of the soil made it a backward region. For many villages fetching water required a long journey by horse. Since water often needed to be stored over a long time, it was often stagnant. Thus disinfection via alcohol was very popular: "Most" ( cider ) was mixed with water and even given to babies. A modern water supply system (outstanding for its time) was built in the late 1880s, which eased

7296-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon

7392-485: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above

7488-455: The situation. Locals in the areas speak the distinct German dialect known as Swabian German , which varies even throughout the Jura and is difficult to understand for speakers of Standard German. The dialect at the top of the plateau ( German : Albschwäbisch ) is markedly different from, and stronger than, even the broadest Swabian of the lowland areas. Across the whole Swabian region, many phrases and grammar are highly localized, even down to

7584-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism

7680-456: The strongest fortresses of his duchy. During this time, it began to be used as a prison, and in 1526, Hans Müller von Bulgenbach , a peasant commander, was imprisoned there before he was executed. The fortress resisted five Imperial sieges in the Thirty Years' War , under the command of Konrad Widerholt between 1634 and 1648. The effect was that Württemberg remained Protestant, while most of

7776-573: The surrounding areas returned to Catholicism in the Counterreformation . The castle served as a Württemberg prison in the 18th century and was destroyed in 1801 after being peacefully handed over to the French. Today the former fortress Hohentwiel is the biggest castle ruin in Germany. Volcano A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from

7872-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into

7968-469: The surrounding dry surface area to wear away. The material was deposited in the still-flooded depression, forming a molassae basin on the sea floor (marine molasse). With a thickness of roughly 5000 metres, the resulting molasse blanket filled the space between the two continents. During the Miocene period (c. 23-5.3 million years ago), after the flood waters receded, the deep fractures and stresses caused from

8064-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath

8160-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where

8256-400: The town in Germany where it is simplest to open a new business. Educational resources are at a high level. The schools and universities of the region all enjoy top rankings within Germany. The Swabian Jura and the neighbouring region have developed from one of the poorest regions of Germany to one of its richest within the past 150 years. In winter it often snows. Skiing is popular (though

8352-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in

8448-504: The uplift of the Alps and Swabian Alb resulted in intraplate volcanism . This type of volcanism is not caused by the movement of a tectonic plate , but rather is a result of uplift with a single continental plate. This volcanism is believed to have been caused by the convergence of the Bonndorfer Graben fault, running northwest-southeast, and a north-south fault extending from Höwenegg to Riedheim . Active volcanoes were present for

8544-426: The village level; however, the Swabian dialect of the highland regions is characterised by a sing-song melody, and some of the verb forms are also distinct, not only from Standard German , but also from those of the rest of Swabia . In former times, Yiddish , Pleißne and Romani was also spoken. The Pleißne was spoken by hawkers selling items such as baskets, brushes, and whips, and belongs to Rotwelsch . It

8640-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of

8736-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of

8832-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in

8928-459: Was discovered in the 1970s and has been turned into an outdoor museum. The limes actually cuts across the plateau at Aalen , which gets its name from the original Roman cavalry post, or ala , on the outskirts of the modern town. Here too, the Roman ruins are being excavated and a museum has been open to the public since the late 1980s. Life was extremely hard in the Swabian Jura. The lack of water and

9024-408: Was popular. This yielded the development of a strong textile industry. In the 1950s, Reutlingen was the German town with the highest number of millionaires, until the decline of the German textile industry hit them as well. Still, many high quality textile companies can be found, such as Hugo Boss , Merz b. Schwanen , Trigema , Reusch, Groz-Beckert and others (the town of Metzingen is widely known as

9120-429: Was the last strongly formative period in Earth's glacial history , characterised by four major glacial periods: Günz (400,000 - 300,000 years ago), Mindel (300,000 - 200,000 years ago), Riß 200,000 - 130,000 years ago) and Würm (20,000 years ago). During these periods, Alpine glaciers continued to erode the landscape. The Würm glaciation saw the Rhine glacier advance northward. The Lake Constance foreland glacier, part of

9216-658: Was used as a code. The " Swabian – Alemannic " carnival is an important tradition in many of the villages, called variously " Fastnacht ", "Fasnacht", "Fasnet", or "Fasching". Of particular cultural importance is the Fasnet celebration in Rottweil. Typical of the Allemannic tradition are the witches and forest- or well-spirits, who typically signify Winter or the forces of nature coming to drive Winter out. The various roles are often claimed to have been defined in pre-Christian times and here

#842157