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27-583: Middle Teton (12,809 feet (3,904 m)) is the third-highest peak in the Teton Range , in the U.S. state of Wyoming . Located within Grand Teton National Park , the peak is immediately southwest of Grand Teton , from which it is separated by a broad high ridge at 11,600 feet (3,540 m), known to local climbers as the Lower Saddle . The Middle Teton Glacier is located on the eastern slopes of

54-909: A weak tendency to fracture along these layers. In Europe, the term has been more widely applied to any coarse, mica -poor, high-grade metamorphic rock. The British Geological Survey (BGS) and the International Union of Geological Sciences (IUGS) both use gneiss as a broad textural category for medium- to coarse-grained metamorphic rock that shows poorly developed schistosity, with compositional layering over 5 millimeters (0.20 in) thick and tending to split into plates over 1 centimeter (0.39 in) thick. Neither definition depends on composition or origin, though rocks poor in platy minerals are more likely to produce gneissose texture. Gneissose rocks thus are largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals. Metamorphic rock showing stronger schistosity

81-475: Is a gneiss resulting from metamorphism of granite, which contains characteristic elliptic or lenticular shear-bound grains ( porphyroclasts ), normally feldspar , surrounded by finer grained material. The finer grained material deforms around the more resistant feldspar grains to produce this texture. Migmatite is a gneiss consisting of two or more distinct rock types, one of which has the appearance of an ordinary gneiss (the mesosome ), and another of which has

108-518: Is called gneissic banding. The darker bands have relatively more mafic minerals (those containing more magnesium and iron ). The lighter bands contain relatively more felsic minerals (minerals such as feldspar or quartz , which contain more of the lighter elements, such as aluminium , sodium , and potassium ). The banding is developed at high temperature when the rock is more strongly compressed in one direction than in other directions ( nonhydrostatic stress ). The bands develop perpendicular to

135-449: Is classified as schist, while metamorphic rock devoid of schistosity is called a granofels . Gneisses that are metamorphosed igneous rocks or their equivalent are termed granite gneisses, diorite gneisses, and so forth. Gneiss rocks may also be named after a characteristic component such as garnet gneiss, biotite gneiss, albite gneiss, and so forth. Orthogneiss designates a gneiss derived from an igneous rock , and paragneiss

162-583: Is described as a "classic", and is one of the few early season purely ice and snow routes in the Teton Range . Teton Range The Teton Range is a mountain range of the Rocky Mountains in North America . It extends for approximately 40 miles (64 km) in a north–south direction through the U.S. state of Wyoming , east of the Idaho state line. It is south of Yellowstone National Park , and most of

189-510: Is one from a sedimentary rock . Both the BGS and the IUGS use gneissose to describe rocks with the texture of gneiss, though gneissic also remains in common use. For example, a gneissose metagranite or a gneissic metagranite both mean a granite that has been metamorphosed and thereby acquired gneissose texture. The minerals in gneiss are arranged into layers that appear as bands in cross section. This

216-506: Is subjected to extreme temperature and pressure and is composed of alternating layers of sandstone (lighter) and shale (darker), which is metamorphosed into bands of quartzite and mica. Another cause of banding is "metamorphic differentiation", which separates different materials into different layers through chemical reactions, a process not fully understood. Augen gneiss , from the German : Augen [ˈaʊɡən] , meaning "eyes",

243-631: The Cambrian period, deep deposits of sedimentary rock were deposited in shallow seas over the metamorphic basement rocks. Erosion and uplift have exposed the metamorphic and intrusive igneous rocks now visible on the east slope of the range and in the Cathedral Group and the Paleozoic and Cenozoic sedimentary rocks on the west slope. As recently as 2.1 million years ago the Huckleberry Ridge Tuff

270-689: The Earth's crust caused movement along the Teton fault . The west block along the fault line rose to form the Teton Range, creating the youngest mountain range in the Rocky Mountains. The fault's east block fell to form the valley called Jackson Hole . The geological processes that led to the current composition of the oldest rocks in the Teton Range began about 2.5 billion years ago. At that time, sand and volcanic debris settled into an ancient ocean. Additional sediment

297-454: The Lower Saddle, a distinctive feature known as the black dike appears as a straight line running from near the top of the mountain down 800 feet (240 m). The black dike is a basaltic intrusion that occurred long after the surrounding rock was formed. The first recorded ascent of Middle Teton was by Albert R. Ellingwood on August 23, 1923, via Ellingwood Couloir on the south side of

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324-453: The amphibolite or granulite facies. These form most of the exposed rock in Archean cratons . Gneiss domes are common in orogenic belts (regions of mountain formation). They consist of a dome of gneiss intruded by younger granite and migmatite and mantled with sedimentary rock. These have been interpreted as a geologic record of two distinct mountain-forming events, with the first producing

351-538: The appearance of an intrusive rock such pegmatite , aplite , or granite the ( leucosome ). The rock may also contain a melanosome of mafic rock complementary to the leucosome. Migmatites are often interpreted as rock that has been partially melted, with the leucosome representing the silica-rich melt, the melanosome the residual solid rock left after partial melting, and the mesosome the original rock that has not yet experienced partial melting. Gneisses are characteristic of areas of regional metamorphism that reaches

378-416: The bottom of the deck in the other direction. These forces stretch out the rock like a plastic , and the original material is spread out into sheets. Per the polar decomposition theorem , the deformation produced by such shearing force is equivalent to rotation of the rock combined with shortening in one direction and extension in another. Some banding is formed from original rock material (protolith) that

405-575: The central massif, sometimes referred to as the Cathedral Group , are Grand Teton (13,775 feet (4,199 m)), Mount Owen (12,928 feet (3,940 m)), Teewinot (12,325 feet (3,757 m)), Middle Teton (12,804 feet (3,903 m)) and South Teton (12,514 feet (3,814 m)). Other peaks in the range include Mount Moran (12,605 feet (3,842 m)), Mount Wister (11,490 feet (3,500 m)), Buck Mountain (11,938 feet (3,639 m)) and Static Peak (11,303 feet (3,445 m)). Between six and nine million years ago, stretching and thinning of

432-402: The direction of greatest compression, also called the shortening direction, as platy minerals are rotated or recrystallized into parallel layers. A common cause of nonhydrodynamic stress is the subjection of the protolith (the original rock material that undergoes metamorphism) to extreme shearing force, a sliding force similar to the pushing of the top of a deck of cards in one direction, and

459-581: The east side of the range is within Grand Teton National Park . One theory says the early French voyageurs named the range les trois tétons ("the three nipples") after the breast-like shapes of its peaks. Another theory says the range is named for the Teton Sioux (from Thítȟuŋwaŋ), also known as the Lakota people . It is likely that the local Shoshone people once called the whole range Teewinot , meaning "many pinnacles". The principal summits of

486-535: The granite basement and the second deforming and melting this basement to produce the domes. However, some gneiss domes may actually be the cores of metamorphic core complexes , regions of the deep crust brought to the surface and exposed during extension of the Earth's crust . The word gneiss has been used in English since at least 1757. It is borrowed from the German word Gneis , formerly also spelled Gneiss , which

513-521: The middle amphibolite to granulite metamorphic facies . In other words, the rock was metamorphosed at a temperature in excess of 600 °C (1,112 °F) at pressures between about 2 to 24 kbar . Many different varieties of rock can be metamorphosed to gneiss, so geologists are careful to add descriptions of the color and mineral composition to the name of any gneiss, such as garnet-biotite paragneiss or grayish-pink orthogneiss . Continental shields are regions of exposed ancient rock that make up

540-497: The oldest rocks on Earth are gneisses, such as the Acasta Gneiss . In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding ( gneissic banding ) but poorly developed schistosity and indistinct cleavage . In other words, it is a metamorphic rock composed of mineral grains easily seen with the unaided eye, which form obvious compositional layers, but which has only

567-474: The peak. Middle Teton is a classic pyramidal alpine peak and is sometimes included as part of the Cathedral Group of high Teton peaks. The 40-mile-long (64 km) Teton Range is the youngest mountain chain in the Rocky Mountains , beginning its uplift 9 million years ago, during the Miocene . Several periods of glaciation have carved Middle Teton and the other peaks of the range into their current shapes. From

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594-552: The peak. Ellingwood made the first ascent of South Teton the same day. What is known as the southwest couloir provides the easiest route to the summit. Other sections on the mountain are rated as high as class 5.11 , with the Middle Teton Glacier route considered to be the most technically advanced. The first ascent of the Glacier Route was completed on August 4, 1944, by Paul Bradt and Sterling Hendricks. This route

621-596: The stable cores of continents. The rock exposed in the oldest regions of shields, which is of Archean age (over 2500 million years old), mostly belong to granite-greenstone belts. The greenstone belts contain metavolcanic and metasedimentary rock that has undergone a relatively mild grade of metamorphism, at temperatures of 350–500 °C (662–932 °F) and pressures of 200–500 MPa (2,000–5,000 bar). The greenstone belts are surrounded by high-grade gneiss terrains showing highly deformed low-pressure, high-temperature (over 500 °C (932 °F)) metamorphism to

648-515: The view. This is due to the presence of the Teton Fault at the base of the east slope as well as the range being too young to have eroded into soft hills. The Snake River flows southward through the valley before turning to the west and entering Idaho. The Tetons and Jackson Hole have been the setting for a number of films, including John Wayne 's film acting debut in The Big Trail in 1930 and

675-447: The western film classic Shane in 1953. Mount Moran and the surrounding mountains were used as a backdrop for the lake/swamp setting in the original television series Land of the Lost . In addition, this mountain range is shown on the cover of rapper Kanye West 's eighth studio album Ye . Gneiss Gneisses are common in the ancient crust of continental shields . Some of

702-403: Was deposited along the west slope of the north part of the range. One reason the Teton Range is famous is because of the dramatic elevation profile visible from the eastern side, which rises sharply from 4,000 to 7,000 feet (1,200–2,100 m) above the valley floor. Unlike most mountain ranges, the east side of the Teton Range lacks significant foothills or lower peaks which might obscure

729-469: Was deposited for millions of years and eventually heat and pressure metamorphosed the sediment into gneiss . Subsequently, magma was forced up through the cracks in the gneiss to form granite , anywhere from inches to hundreds of feet thick. Other intrusive igneous rocks are noticeable as the black dikes of diabase , visible on the southwest face of Mount Moran and on the Grand Teton . Starting during

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