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Highwood Mountains
The Highwood Mountains are an island range (sub-range of the Rockies entirely surrounded by prairie) which cover approximately 4,659 km² (1,799 sq mi) of the Central Montana Alkalic Province in north central Montana in the U.S. They are in Chouteau, Judith Basin and Cascade counties and lie east of Great Falls and Benton Lake National Wildlife Refuge, at the northern end of the Lewis and Clark National Forest. The mountains were included in Highwood Mountains National Forest until 1908, when the unit became part of Lewis and Clark National Forest. Nearby are Highwood, Montana and the Missouri River above the mouth of the Marias River. The highest point in the Highwood Mountains is Highwood Baldy at 2338 meters (7670 ft). The area has volcanic origins and is rich in potash. Many of the extrusive rocks and some of the dike rocks contain abundant phenocrysts of a clear analcime that appears to be primary. Pseudoleucite is an abundant constituent of many of the igneous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Montana Alkalic Province
The central Montana Alkalic Province is located in the United States in central Montana. Montana is bordered by Idaho, Wyoming, North Dakota, South Dakota, and Canada to the north. Central Montana is unique when compared to the rest of the Rocky Mountains due to its east-west trend of tectonic features, including thrust fault zones, anticlines, and domes. The area of tectonic activity experienced conditions of plastic deformation, which affected the whole region. The Montana Alkalic Province consist of Cretaceous intrusions of monzonite and syenite as well as Cambrian limestone, sandstone, and siltstone. Most of the sedimentary rocks are a result of deposition from a terrestrial fluvial environment. Deposition included more than 13,000 feet of clastics that were later uplifted. The peak of this uplifting occurred during the Devonian. Deposition, uplift, and traps of carbonate shales have made central Montana prime for small-scale oil and gas production. Other geologic formations in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrusive Rock
Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the Earth's atmosphere, atmosphere to fall back as Pyroclastic rock, pyroclastics or tuff. In contrast, intrusive rock refers to rocks formed by magma which cools below the surface.Jain, Sreepat (2014). ''Fundamentals of Physical Geology''. New Delhi, India: Springer. . The main effect of extrusion is that the magma can cool much more quickly in the open air or under seawater, and there is little time for the growth of crystals. Sometimes, a residual portion of the matrix (geology), matrix fails to crystallize at all, instead becoming a natural glass or obsidian. If the magma contains abundant Volatiles, volatile components which are released as free gas, then it may cool with large or small vesicles (bubble-shaped cavities) such as in pumice, scoria, or vesicular texture, vesicular basalt. Other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Montana
The geology of Montana includes thick sequences of Paleozoic, Mesozoic and Cenozoic sedimentary rocks overlying ancient Archean and Proterozoic crystalline basement rock. Eastern Montana has considerable oil and gas resources, while the uplifted Rocky Mountains in the west, which resulted from the Laramide orogeny and other tectonic events have locations with metal ore. Geologic History, Stratigraphy & Tectonics The oldest rocks in Montana are part of the Archean Wyoming Craton in the center and east of the state, primarily between Livingston and Red Lodge, as well as small areas in the Little Belt Mountains around Neihart and the core of the Little Rocky Mountains south of Harlem. Drill cores indicate that these rocks underlie much of the Great Plains. The Pony Group, Cherry Creek Group and the Stillwater Complex are examples of Precambrian metamorphic rock units The first two groups are made up of folded and metamorphosed marine sedimentary rocks which were folded, metamorphosed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mountain Ranges Of Montana
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher than a hill, typically rising at least 300 metres (1,000 feet) above the surrounding land. A few mountains are isolated summits, but most occur in mountain ranges. Mountains are formed through tectonic forces, erosion, or volcanism, which act on time scales of up to tens of millions of years. Once mountain building ceases, mountains are slowly leveled through the action of weathering, through slumping and other forms of mass wasting, as well as through erosion by rivers and glaciers. High elevations on mountains produce colder climates than at sea level at similar latitude. These colder climates strongly affect the ecosystems of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Mountain Ranges In Montana
This is a list of mountain ranges in the state of Montana. Montana is the fourth largest state in the United States and is well known for its mountains. The name "Montana" means "mountainous" in Latin. Representative James Mitchell Ashley ( R-Ohio), suggested the name when legislation organizing the territory was passed by the United States Congress in 1864. Ashley noted that a mining camp in the Colorado Territory had already used the name, and Congress agreed to use the name for the new territory. According to the United States Board on Geographic Names, there are at least 100 named mountain ranges and sub-ranges in Montana. However, mountain ranges have no official boundaries, and there is no official list of mountain ranges in the state. List of mountain ranges The mountain ranges below are listed by name, county, coordinates, and average elevation as recorded by the U.S. Geological Survey. Sub-ranges are indented below the name of the primary range. Some of these ranges exte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highwood Mountains Montana Southeast Face 17 , a wood in north-east France, scene of a World War I conflict
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Highwood may refer to: People * Sidney Highwood (1896–1975), World War I flying ace Places Canada * Highwood, Calgary, a neighbourhood in Calgary, Alberta * Highwood (electoral district), a provincial electoral district in Alberta * Highwood River, a river in Alberta United Kingdom * Highwood, Devon * Highwood, Dorset * Highwood, Essex * Highwood, Hampshire * Highwood, Wokingham, a Local Nature Reserve * Highwood, Worcestershire United States * Highwood, Illinois * Highwood, Montana * Highwood, Wisconsin * Highwood, Hamden, a neighborhood in the town of Hamden, Connecticut Philippines * Highwood, Batangas, Philippines See also * High Wood The Attacks on High Wood, near Bazentin le Petit in the Somme ''département'' of northern France, took place between the British Fourth Army and the German 1st Army during the Battle of the Somme. After the Battle of Bazentin Ridge on 14 July ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meltwater Channel
A meltwater channel (or sometimes a glacial meltwater channel) is a channel cut into ice, bedrock or unconsolidated deposits by the flow of water derived from the melting of a glacier or ice-sheet. The channel may form on the surface of, within, beneath, along the margins of or downstream from the ice mass. Accordingly it would be referred to as supraglacial, englacial, subglacial, lateral (or ice-marginal) or proglacial. Different forms of subglacial channel are described in glaciological literature including Nye or N-channels, Röthlisberger or R-channels and Hooke or H-channels. Tunnel valley is a related term descriptive of subglacial channels. Some examples of tunnel valleys in northwest England have also been described as iceways. The depositional landforms known as kames and eskers may often be found in association with meltwater channels. An urstromtal is a proglacial or ice-marginal channel common in Germany and Poland formed during various of the Pleistocene glaciat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shonkin Sag
The Shonkin Sag is a prehistoric fluvioglacial landform located along the northern edge of the Highwood Mountains in the state of Montana in the United States. The Sag is a river channel formed by the Missouri River and glacial meltwater pouring from Glacial Lake Great Falls. It is one of the most famous prehistoric meltwater channels in the world. Location and size Shonkin Sag is located in central Montana. It begins south of Highwood, Montana, (about east of the city of Great Falls, Montana, Great Falls) and runs in an easterly direction for about until it reaches the Judith River."Societies and Academies: Geological Society of Washington." ''Science (journal), Science.'' May 7, 1895, p. 559-560. It varies from to in width and is about deep. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Igneous Rock
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava. The magma can be derived from Partial melting, partial melts of existing rocks in either a Terrestrial planet, planet's mantle (geology), mantle or crust (geology), 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 (geology), extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form Volcanic glass, natural glasses. Igneous rocks occur in a wide range of geological settings: shields, platforms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucite
Leucite is a rock-forming mineral of the feldspathoid group, silica-undersaturated and composed of potassium and aluminium tectosilicate KAlSi2O6. Crystals have the form of cubic icositetrahedra but, as first observed by Sir David Brewster in 1821, they are not optically isotropic, and are therefore pseudo-cubic. Goniometric measurements made by Gerhard vom Rath in 1873 led him to refer the crystals to the tetragonal system. Optical investigations have since proved the crystals to be still more complex in character, and to consist of several orthorhombic or monoclinic individuals, which are optically biaxial and repeatedly twinned, giving rise to twin-lamellae and to striations on the faces. When the crystals are raised to a temperature of about 500 °C they become optically isotropic and the twin-lamellae and striations disappear, although they reappear when the crystals are cooled again. This pseudo-cubic character of leucite is very similar to that of the mineral boracit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analcime
Analcime (; ) or analcite is a white, gray, or colorless tectosilicate mineral. Analcime consists of hydrated sodium aluminium silicate in cubic crystalline form. Its chemical formula is Na Al Si2 O6· H2O. Minor amounts of potassium and calcium substitute for sodium. A silver-bearing synthetic variety also exists (Ag-analcite). Analcime is usually classified as a zeolite mineral, but structurally and chemically it is more similar to the feldspathoids. Analcime occurs as a primary mineral in analcime basalt and other alkaline igneous rocks. It also occurs as cavity and vesicle fillings associated with prehnite, calcite, and zeolites. Locations Well known locations for sourcing analcime include Croft Quarry in Leicestershire, UK; the Cyclopean Islands east off Sicily and near Trentino in northern Italy; Victoria in Australia; Kerguelen Island in the Indian Ocean; in the Lake Superior copper district of Michigan, Bergen Hill, New Jersey, Golden, Colorado, and at Searles Lake, C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenocrysts
300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter 2.3 cm) for scale. A phenocryst is an early forming, relatively large and usually conspicuous crystal distinctly larger than the grains of the rock groundmass of an igneous rock. Such rocks that have a distinct difference in the size of the crystals are called porphyries, and the adjective porphyritic is used to describe them. Phenocrysts often have euhedral forms, either due to early growth within a magma, or by post-emplacement recrystallization. Normally the term ''phenocryst'' is not used unless the crystals are directly observable, which is sometimes stated as greater than .5 millimeter in diameter. Phenocrysts below this level, but still larger than the groundmass crystals, are termed ''microphenocrysts''. Very large phenocrysts a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
