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Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi3O8 to CaAl2Si2O8), where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or 'record-groove' effect.
Andesite is an extrusive volcanic rock of intermediate composition. In a general sense, it is the intermediate type between basalt and rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
Mount Bailey is a relatively young tephra cone and shield volcano in the Cascade Range, located on the opposite side of Diamond Lake from Mount Thielsen in southern Oregon, United States. Bailey consists of a 2,000-foot (610 m)-high main cone on top of an old basaltic andesite shield volcano. With a volume of 8 to 9 km3, Mount Bailey is slightly smaller than neighboring Diamond Peak. Mount Bailey is a popular destination for recreational activities. Well known in the Pacific Northwest region as a haven for skiing in the winter months, the mountain's transportation, instead of a conventional chairlift, is provided by snowcats—treaded, tractor-like vehicles that can ascend Bailey's steep, snow-covered slopes and carry skiers to the higher reaches of the mountain. In the summer months, a 5-mile (8 km) hiking trail gives foot access to Bailey's summit.
Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone. They are the principal way by which continental growth is achieved.
Mount Mazama is a complex volcano in the state of Oregon, United States, in a segment of the Cascade Volcanic Arc and Cascade Range. Most of the mountain collapsed following a major eruption approximately 7,700 years ago. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon-California border. Its collapse formed a caldera that holds Crater Lake. The mountain is in Crater Lake National Park. Mount Mazama originally had an elevation of 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the US and the second deepest in North America after Great Slave Lake in Canada.
The andesite line is the most significant regional geologic distinction in the Pacific Ocean basin. It separates the mafic basaltic volcanic rocks of the Central Pacific Basin from the partially submerged continental areas of more felsic andesitic volcanic rock on its margins. The andesite line parallels the subduction zones and deep oceanic trenches around the Pacific basin. It is the surface expression of melting within and above the plunging subducting slab. It follows the western edge of the islands off California and passes south of the Aleutian Arc, along the eastern edge of the Kamchatka Peninsula, the Kuril Islands, Japan, the Mariana Islands, Yap, Palau, the Solomon Islands, Fiji, Tonga, and New Zealand's North Island. The dissimilarity continues northeastward along the western edge of the Andes mountains of South America to Mexico, returning then to the islands off California. Indonesia, the Philippines, Japan, New Guinea, and New Zealand lie outside the andesite line.
The Table, sometimes called Table Mountain, is a 2,021-metre (6,631 ft) high flow-dominated andesite tuya located 4 kilometres (2 mi) south of Garibaldi Lake, 15 kilometres (9 mi) northeast of Cheekye and 5 kilometres (3 mi) north of Mount Garibaldi, British Columbia, Canada. It rises over 530 metres (1,740 ft) above the surface of Garibaldi Lake, which lies less than 1 kilometre (1 mi) to the north.
The Karpinsky Group is a volcanic group located at the southern end of Paramushir Island, Kuril Islands, Russia. The group is capped by two gently sloping cones rising to a height of 1345 m. They are composed of andesites and andesite-basalts. In the two craters there are fumaroles and fountains of liquid sulfur. The last major, and only historic, eruption was in 1952. The sides of the volcanoes have been heavily glaciated leaving a number of cirques which were initially thought to be eroded craters. The volcanoes were named after the geologist Aleksandr Petrovich Karpinsky.
Barnacle Bill is a 40-centimetre (16 in) rock on Mars in Ares Vallis. It was the first rock on Mars analyzed by the Sojourner rover using its Alpha Proton X-ray Spectrometer. The encounter occurred during Sol 3 of the Mars Pathfinder mission on the surface of Mars and took ten hours to complete.
Lonquimay Volcano is a stratovolcano of late-Pleistocene to dominantly Holocene age, with the shape of a truncated cone. The cone is largely andesitic, though basaltic and dacitic rocks are present. It is located in the La Araucanía Region of Chile, immediately SE of Tolhuaca volcano. Sierra Nevada and Llaima are their neighbors to the south. The snow-capped volcano lies within the protected area Malalcahuello-Nalcas.
Diamond Peak is a volcano in Klamath and Lane counties of central Oregon in the United States. It is a shield volcano, though it might also be considered a modest stratocone. Diamond Peak forms part of the Cascade Volcanic Arc, a segment of the Cascade Range in western North America extending from southern British Columbia through Oregon to Northern California. Reaching an elevation of 8,748 feet (2,666 m), the mountain is located near Willamette Pass in the Diamond Peak Wilderness within the Deschutes and Willamette national forests. Surrounded by coniferous forest and visible in the skyline from foothills near Eugene, Diamond Peak offers a few climbing routes and can be scrambled.
The Boulder Creek Wilderness is a wilderness area located in the Umpqua National Forest in the southern Cascade Range of Oregon, United States. It was designated by the United States Congress in 1984 and comprises 19,100 acres (7,729 ha).
Cauldron Dome is a tuya in the Mount Cayley volcanic field, British Columbia, Canada. Cauldron Dome is made of coarsely plagioclase-orthophyroxene-phyric andesite lava flows and last erupted during the Holocene. It is in the Garibaldi Volcanic Belt, a portion of the Canadian Cascade Arc.
The Western Cascades is a region of the U.S. state of Oregon between the Willamette Valley and the High Cascades. The range contains many extinct shield volcanoes, cinder cones and lava flows. The range is highly eroded and heavily forested.
Nevado San Francisco, or Cerro San Francisco, is a stratovolcano on the border between Argentina and Chile, located just southeast of San Francisco Pass. It is considered extinct and is one of the several 6,000 m (19,700 ft) peaks in the area, of which the chief is the Ojos del Salado.
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms, orogens, basins, large igneous provinces, extended crust and oceanic crust.
Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central America and the Andes of South America.
Crevasse Crag is a jagged steep-sided prominence on the summit of a glaciated mountain ridge in the Lillooet Ranges of southwestern British Columbia, Canada. It is located about 49 km (30 mi) southeast of the village of Pemberton. Situated on the boundary between New Westminster Land District and Kamloops Division Yale Land District, the peak has a maximum elevation of 2,496 m (8,189 ft) and a topographic prominence of 66 m (217 ft).
Minori Cave is part of the Callao limestone formation, located in Barangay Quibal, Municipality of Peñablanca, Cagayan Province in Northern Luzon. The said cave has two openings. One, designated as Mouth B, is located at 17° 43' 17" N latitude and 121° 49' 42" E longitude. The other opening, Mouth A is located 17° 43' 21" N latitude and 121° 49' 44" E longitude. The cave has an average elevation of about 200 m (656.2 ft) above sea level, and length and width of 147 m (482.3 ft) and 7 to 11 m, respectively. The cave is divided into four chambers with mouth A as chamber A and mouth B as chamber D. Chambers B and C are in between the two mouths.
Licto is a volcanic field in Ecuador, close to the town of Licto.
References
- 1 2 3 "Paleobiology Database - Andesites" . Retrieved 2017-10-19.
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