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27-766: The Hochsimmer is a volcanic cone , 587.9 m above  sea level (NHN) , in the Eifel Mountains in Germany . It rises near Ettringen in the Rhineland-Palatine county of Mayen-Koblenz . At the summit is an observation tower, the Hochsimmer Tower . The Hochsimmer rises within the High Eifel ( East Eifel ) around 1.7 km west-northwest of the village of Ettringen . Flowing past its western foot roughly from north to south

54-416: A cylindrical vent. Unlike shield volcanoes , they are characterized by a steep profile and periodic, often alternating, explosive eruptions and effusive eruptions . Some have collapsed craters called calderas . The central core of a stratocone is commonly dominated by a central core of intrusive rocks that range from around 500 meters (1,600 ft) to over several kilometers in diameter. This central core

81-430: A few days to a few years. Of observed cinder cone eruptions, 50% have lasted for less than 30 days, and 95% stopped within one year. In case of Parícutin, its eruption lasted for nine years from 1943 to 1952. Rarely do they erupt either two, three, or more times. Later eruptions typically produce new cones within a volcanic field at separation distances of a few kilometers and separate by periods of 100 to 1,000 years. Within

108-498: A silica content between 45 and 55 wt% , corresponding to the silica content of basalt in the TAS classification . Such rocks are enriched in iron, magnesium and calcium and typically dark in color. In contrast, the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium . The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to

135-1026: A single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is noticeably symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit. The basal diameters of cinder cones average about 800 meters (2,600 ft) and range from 250 to 2,500 meters (820 to 8,200 ft). The diameter of their craters ranges between 50 and 600 meters (160 and 1,970 ft). Cinder cones rarely rise more than 50–350 meters (160–1,150 ft) or so above their surroundings. Cinder cones most commonly occur as isolated cones in large basaltic volcanic fields. They also occur in nested clusters in association with complex tuff ring and maar complexes. Finally, they are also common as parasitic and monogenetic cones on complex shield and stratovolcanoes. Globally, cinder cones are

162-399: A tuff cone have commonly been altered, palagonitized , by either its interaction with groundwater or when it was deposited warm and wet. The pyroclastic deposits of tuff cones differ from the pyroclastic deposits of spatter cones by their lack or paucity of lava spatter, smaller grain-size, and excellent bedding. Typically, but not always, tuff cones lack associated lava flows. A tuff ring

189-525: A volcanic field, eruptions can occur over a period of a million years. Once eruptions cease, being unconsolidated, cinder cones tend to erode rapidly unless further eruptions occur. Rootless cones , also called pseudocraters , are volcanic cones that are not directly associated with a conduit that brought magma to the surface from a deep-seated magma reservoir. Generally, three types of rootless cones, littoral cones , explosion craters , and hornitos are recognized. Littoral cones and explosion craters are

216-611: Is 587.9 m high and the East Top ( East Top 50°21′36.3″N 7°12′9.1″E  /  50.360083°N 7.202528°E  / 50.360083; 7.202528 ) is 583.3 m high. About 600 metres southwest of the summit is the Kleiner Simmer (514.7 m). On the east top of the Hochsimmer stands the 18-metre-high Hochsimmer Tower , an observation tower built in 1909 and 1911. From its viewing platform there

243-575: Is a portmanteau of "magnesium" and "ferric" and was coined by Charles Whitman Cross , Joseph P. Iddings , Louis V. Pirsson , and Henry Stephens Washington in 1912. Cross' group had previously divided the major rock-forming minerals found in igneous rocks into salic minerals, such as quartz , feldspars , or feldspathoids , and femic minerals, such as olivine and pyroxene . However, micas and aluminium-rich amphiboles were excluded, while some calcium minerals containing little iron or magnesium, such as wollastonite or apatite , were included in

270-637: Is a low, steep-sided hill or mound that consists of welded lava fragments, called spatter, which has formed around a lava fountain issuing from a central vent. Typically, spatter cones are about 3–5 meters (9.8–16.4 ft) high. In case of a linear fissure, lava fountaining will create broad embankments of spatter, called spatter ramparts, along both sides of the fissure. Spatter cones are more circular and cone shaped, while spatter ramparts are linear wall-like features. Spatter cones and spatter ramparts are typically formed by lava fountaining associated with mafic , highly fluid lavas, such as those erupted in

297-408: Is a related type of small monogenetic volcano that is also produced by phreatic (hydrovolcanic) explosions directly associated with magma brought to the surface through a conduit from a deep-seated magma reservoir. They are characterized by rims that have a low, broad topographic profiles and gentle topographic slopes that are 25 degrees or less. The maximum thickness of the pyroclastic debris comprising

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324-666: Is a small monogenetic volcanic cone produced by phreatic (hydrovolcanic) explosions directly associated with magma brought to the surface through a conduit from a deep-seated magma reservoir. They are characterized by high rims that have a maximum relief of 100–800 meters (330–2,620 ft) above the crater floor and steep slopes that are greater than 25 degrees. They typically have a rim to rim diameter of 300–5,000 meters (980–16,400 ft). A tuff cone consists typically of thick-bedded pyroclastic flow and surge deposits created by eruption-fed density currents and bomb-scoria beds derived from fallout from its eruption column. The tuffs composing

351-550: Is a view of the Eastern High Eifel , the Middle Rhine Basin and of Ettringen; in good visibility, even Cologne Cathedral may be seen. About 30 metres northwest of the viewing tower is a transmission tower . Volcanic cone Stratocones are large cone-shaped volcanoes made up of lava flows , explosively erupted pyroclastic rocks, and igneous intrusives that are typically centered around

378-466: Is not used as a rock classification in the IUGS classification scheme. Mafic rocks are sometimes more precisely defined as igneous rocks with a high proportion of pyroxene and olivine, so that their color index (the volume fraction of dark mafic minerals) is between 50 and 90. Most mafic volcanic rocks are more precisely classified as basalts . Chemically, mafic rocks are sometimes defined as rocks with

405-722: Is part of the middle reaches of the Rhine tributary, the Nette . Through its valley runs the Landesstraße 83, which links Weibern to the northwest with Mayen to the southeast. At the eastern foot of the hill is the L 82 road to Bell , and, at its southern foot is the village of St. Johann . The Hochsimmer has two domed summits or kuppen : the West Top ( West Top 50°21′38.5″N 7°11′54.8″E  /  50.360694°N 7.198556°E  / 50.360694; 7.198556 )

432-414: Is surrounded by multiple generations of lava flows, many of which are brecciated , and a wide range of pyroclastic rocks and reworked volcanic debris. The typical stratocone is an andesitic to dacitic volcano that is associated with subduction zones . They are also known as either stratified volcano, composite cone, bedded volcano, cone of mixed type or Vesuvian-type volcano. A spatter cone

459-533: The International Union of Geological Sciences (IUGS) classification of igneous rocks, include some light-colored ferromagnesian minerals, such as melilite , in the mafic mineral fraction. Accessory minerals , such as zircon or apatite, may also be included in the mafic mineral fraction for purposes of precise classification. When applied to rocks, the term mafic is used primarily as a field term to describe dark-colored igneous rocks. The term

486-579: The Hawaiian Islands. As blobs of molten lava, spatter, are erupted into the air by a lava fountain, they can lack the time needed to cool completely before hitting the ground. Consequently, the spatter are not fully solid, like taffy , as they land and they bind to the underlying spatter as both often slowly ooze down the side of the cone. As a result, the spatter builds up a cone that is composed of spatter either agglutinated or welded to each other. A tuff cone , sometimes called an ash cone ,

513-426: The calderas and volcanic cones of Ulysses Patera , Ulysses Colles and Hydraotes Chaos are argued to be cinder cones. Cinder cones typically only erupt once like Parícutin. As a result, they are considered to be monogenetic volcanoes and most of them form monogenetic volcanic fields . Cinder cones are typically active for very brief periods of time before becoming inactive. Their eruptions range in duration from

540-422: The crater of a tuff ring generally has been excavated below the existing ground surface. As a result, water commonly fills a tuff ring's crater to form a lake once eruptions cease. Both tuff cones and their associated tuff rings were created by explosive eruptions from a vent where the magma is interacting with either groundwater or a shallow body of water as found within a lake or sea. The interaction between

567-455: The femic minerals. Cross and his coinvestigators later clarified that micas and aluminium amphiboles belonged to a separate category of alferric minerals. They then introduced the term mafic for ferromagnesian minerals of all types, in preference to the term femag coined by A. Johannsen in 1911, whose sound they disliked. The term mafic is still widely used for dark-colored ferromagnesian minerals. Modern classification schemes, such as

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594-638: The magma, expanding steam, and volcanic gases resulted in the production and ejection of fine-grained pyroclastic debris called ash with the consistency of flour . The volcanic ash comprising a tuff cone accumulated either as fallout from eruption columns, from low-density volcanic surges and pyroclastic flows, or combination of these. Tuff cones are typically associated with volcanic eruptions within shallow bodies of water and tuff rings are associated with eruptions within either water saturated sediments and bedrock or permafrost . Next to spatter (scoria) cones, tuff cones and their associated tuff rings are among

621-756: The most common types of volcanoes on Earth. An example of a tuff cone is Diamond Head at Waikīkī in Hawaiʻi . Clusters of pitted cones observed in the Nephentes/Amenthes region of Mars at the southern margin of the ancient Utopia impact basin are currently interpreted as being tuff cones and rings. Cinder cones , also known as scoria cones and less commonly scoria mounds , are small, steep-sided volcanic cones built of loose pyroclastic fragments, such as either volcanic clinkers, cinders, volcanic ash, or scoria . They consist of loose pyroclastic debris formed by explosive eruptions or lava fountains from

648-712: The most typical volcanic landform found within continental intraplate volcanic fields and also occur in some subduction zone settings as well. Parícutin , the Mexican cinder cone which was born in a cornfield on February 20, 1943, and Sunset Crater in Northern Arizona in the US Southwest are classic examples of cinder cones, as are ancient volcanic cones found in New Mexico's Petroglyph National Monument . Cone-shaped hills observed in satellite imagery of

675-494: The result of mild explosions that were generated locally by the interaction of either hot lava or pyroclastic flows with water. Littoral cones typically form on the surface of a basaltic lava flow where it has entered into a body of water, usually a sea or ocean. Explosion craters form where either hot lava or pyroclastic flows have covered either marshy ground or water-saturated ground of some sort. Hornitos are rootless cones that are composed of welded lava fragments and were formed on

702-421: The rim of a typical tuff ring is generally thin, less than 50 meters (160 ft) to 100 meters (330 ft) thick. The pyroclastic materials that comprise their rim consist primarily of relatively fresh and unaltered, distinctly and thin-bedded volcanic surge and air fall deposits. Their rims also can contain variable amounts of local country rock (bedrock) blasted out of their crater. In contrast to tuff cones,

729-620: The surface of basaltic lava flows by the escape of gas and clots of molten lava through cracks or other openings in the crust of a lava flow. Mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron . Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine , pyroxene , amphibole , and biotite . Common mafic rocks include basalt , diabase and gabbro . Mafic rocks often also contain calcium -rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian . The term mafic

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