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26-729: The source of the Genil is in the Sierra Nevada , north of its highest peak Mulhacén . The Genil flows through the towns Granada , Loja , Puente Genil and Écija . It flows into the Guadalquivir River near Palma del Río . Its main tributary is the Darro . It is joined by the Cacín River to the southwest of Villanueva Mesía . The river today drains the Granada basin . In the latest Tortonian and

52-429: A discontinuity that may have a large influence on the mechanical behavior (strength, deformation, etc.) of rock masses in, for example, tunnel , foundation , or slope construction. A hazard may exist even in undisturbed terrain. On August 17, 1959, a magnitude 7.2 earthquake destabilized a mountain slope near Hebgen Lake , Montana, composed of schist. This caused a massive landslide that killed 26 people camping in

78-553: A schistose metasandstone (if the protolith is known to have been a sandstone ). If all that is known is that the protolith was a sedimentary rock, the schist will be described as a paraschist , while if the protolith was an igneous rock, the schist will be described as an orthoschist . Mineral qualifiers are important when naming a schist. For example, a quartz-feldspar-biotite schist is a schist of uncertain protolith that contains biotite mica, feldspar , and quartz in order of apparent decreasing abundance. Lineated schist has

104-416: A preferred direction in schist, often also forming very thin parallel layers. The ease with which the rock splits along the aligned grains accounts for the schistosity. Though not a defining characteristic, schists very often contain porphyroblasts (individual crystals of unusual size) of distinctive minerals, such as garnet , staurolite , kyanite , sillimanite , or cordierite . Because schists are

130-412: A strong linear fabric in a rock which otherwise has well-developed schistosity. Schistosity is developed at elevated temperature when the rock is more strongly compressed in one direction than in other directions ( nonhydrostatic stress ). Nonhydrostatic stress is characteristic of regional metamorphism where mountain building is taking place (an orogenic belt ). The schistosity develops perpendicular to

156-408: A very large class of metamorphic rock, geologists will formally describe a rock as a schist only when the original type of the rock prior to metamorphism (the protolith ) is unknown and its mineral content is not yet determined. Otherwise, the modifier schistose will be applied to a more precise type name, such as schistose semipelite (when the rock is known to contain moderate amounts of mica) or

182-606: Is a mountain range in the Andalusian province of Granada in Spain . It contains the highest point of continental Spain: Mulhacén , at 3,479 metres (11,414 ft) above sea level . It is a popular tourist destination, as its high peaks make skiing possible in one of Europe's most southerly ski resorts , in an area along the Mediterranean Sea predominantly known for its high temperatures and abundant sunshine. At its foothills

208-540: Is a medium-grained metamorphic rock showing pronounced schistosity (named for the rock). This means that the rock is composed of mineral grains easily seen with a low-power hand lens , oriented in such a way that the rock is easily split into thin flakes or plates. This texture reflects a high content of platy minerals, such as mica , talc , chlorite , or graphite . These are often interleaved with more granular minerals, such as feldspar or quartz . Schist typically forms during regional metamorphism accompanying

234-428: Is a ridge running broadly west-south-west - east-north-east. For a substantial distance, the watershed stays consistently above 3,000 metres (9,800 ft). This is sufficient altitude for the peaks to be consistently snow-covered. On the southern side of the range, several long, narrow river valleys lead off towards the south-west, separated by a number of subsidiary ridges. On the steeper and craggier northern side,

260-518: Is discernible, the schist is usually given a name reflecting its protolith, such as schistose metasandstone . Otherwise, the names of the constituent minerals will be included in the rock name, such as quartz-felspar-biotite schist . Schist bedrock can pose a challenge for civil engineering because of its pronounced planes of weakness . The word schist is derived ultimately from the Greek word σχίζειν ( schízein ), meaning "to split", which refers to

286-592: Is found the city of Granada , and a little further south, Almería and Motril . Parts of the range have been included in the Sierra Nevada National Park . The range has also been declared a biosphere reserve . The Sierra Nevada Observatory , the Calar Alto Observatory , and the IRAM 30m telescope are located on the northern slopes at an elevation of 2,800 metres (9,200 ft). The Sierra Nevada

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312-482: Is the orientation of grains in the surrounding medium-grained rock. The composition of the rock must permit formation of abundant platy minerals. For example, the clay minerals in mudstone are metamorphosed to mica, producing a mica schist. Early stages of metamorphism convert mudstone to a very fine-grained metamorphic rock called slate , which with further metamorphism becomes fine-grained phyllite . Further recrystallization produces medium-grained mica schist. If

338-418: Is uncommon but can form from metamorphosis of sedimentary beds containing abundant organic carbon . This may be of algal origin. Graphite schist is known to have experienced greenschist facies metamorphism , for example in the northern Andes . Metamorphosis of felsic volcanic rock , such as tuff, can produce quartz- muscovite schist. In geotechnical engineering a schistosity plane often forms

364-526: The altitude. Above 2,500 metres (8,200 ft) the climate is Mediterranean -influenced subarctic (Dsc), due to the location's high elevation and low summer precipitation. With June and September being around the threshold of 10 °C (50 °F) in mean temperature to avoid the subarctic classification, the climate at a slightly lower elevation is continental highland climate. At an elevation slightly lower than that classification area; where February means average above −3 °C (27 °F); it falls into

390-456: The direction of greatest compression, also called the shortening direction, as platy minerals are rotated or recrystallized into parallel layers. While platy or elongated minerals are most obviously reoriented, even quartz or calcite may take up preferred orientations. At the microscopic level, schistosity is divided into internal schistosity , in which inclusions within porphyroblasts take a preferred orientation, and external schistosity , which

416-425: The ease with which schists can be split along the plane in which the platy minerals lie. Before the mid-19th century, the terms slate , shale and schist were not sharply differentiated by those involved with mining. Geologists define schist as medium-grained metamorphic rock that shows well-developed schistosity. Schistosity is a thin layering of the rock produced by metamorphism (a foliation ) that permits

442-527: The metamorphism proceeds further, the mica schist experiences dehydration reactions that convert platy minerals to granular minerals such as feldspars, decreasing schistosity and turning the rock into a gneiss. Other platy minerals found in schists include chlorite, talc, and graphite. Chlorite schist is typically formed by metamorphism of ultramafic igneous rocks, as is talc schist. Talc schist also forms from metamorphosis of talc-bearing carbonate rocks formed by hydrothermal alteration . Graphite schist

468-502: The middle and late Turolian (9.0–5.3 Ma) this was an endorheic basin . Rivers flowed from the east and southwest into a central lake with no exit. During the Pliocene , the western part of the basin was drained by the paleo-Cacín river system, which flowed to the north and then left the basin to the west. The eastern part was drained by the Alhambra system, or paleo-Genil system, was fed by

494-602: The mountains to the east and fed a small endorheic lake in the north. Some time later, the Genil river changed course to flow west, where it joined the paleo-Cacin system, and the basin became exorheic . 37°41′37″N 5°19′00″W  /  37.69361°N 5.31667°W  / 37.69361; -5.31667 This article related to a river in Spain is a stub . You can help Misplaced Pages by expanding it . Sierra Nevada (Spain) Sierra Nevada ( Spanish: [ˈsjera neˈβaða] ; meaning "snow-covered mountain range")

520-403: The normal cool-summer mediterranean classification transitioning with the hot-summer variety in surrounding lowland areas. This renders Sierra Nevada's climate a highland cooled-down variety of a typical mediterranean climate. Summer and winter daytime temperatures are some 12 °C lower than found in Granada , differences that are even greater in spring as Sierra Nevada takes longer to approach

546-510: The other two divisions being gneiss , which has poorly developed schistosity and thicker layering, and granofels , which has no discernible schistosity. Schists are defined by their texture without reference to their composition, and while most are a result of medium-grade metamorphism, they can vary greatly in mineral makeup. However, schistosity normally develops only when the rock contains abundant platy minerals, such as mica or chlorite . Grains of these minerals are strongly oriented in

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572-400: The process of mountain building ( orogeny ) and usually reflects a medium grade of metamorphism. Schist can form from many different kinds of rocks, including sedimentary rocks such as mudstones and igneous rocks such as tuffs . Schist metamorphosed from mudstone is particularly common and is often very rich in mica (a mica schist ). Where the type of the original rock (the protolith )

598-424: The rock to easily be split into flakes or slabs less than 5 to 10 millimeters (0.2 to 0.4 in) thick. The mineral grains in a schist are typically from 0.25 to 2 millimeters (0.01 to 0.08 in) in size and so are easily seen with a 10× hand lens . Typically, over half the mineral grains in a schist show a preferred orientation. Schists make up one of the three divisions of metamorphic rock by texture , with

624-556: The short summers. In May daytime highs in Sierra Nevada are around 4 °C (39 °F) with Granada having an average of 24 °C (75 °F). The yearly temperature of 3.9 °C (39.0 °F) at the ski station of Pradollano is in stark contrast to Granada 's 15.7 °C (60.3 °F) and coastal Málaga 's 18.5 °C (65.3 °F). [REDACTED] Media related to Sierra Nevada (Spain) at Wikimedia Commons Schist Schist ( / ˈ ʃ ɪ s t / SHIST )

650-547: The valleys have less regular orientations. This side is dominated by the Rio Genil which starts near Mulhacén and into which many of the other rivers flow. Geologically, the range is composed chiefly of soft micaceous schists , sloping steeply to the north, but more gradually to the south and south-east. According to the Köppen climate classification , Sierra Nevada has a Mediterranean climate , with different variations depending on

676-744: Was formed during the Alpine Orogeny , a mountain-building event that also formed the European Alps to the east and the Atlas Mountains of northern Africa across the Mediterranean Sea to the south. The Sierra as observed today formed during the Paleogene and Neogene Periods (66 to 1.8 million years ago) from the collision of the African and Eurasian continental plates . Central to the mountain range

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