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Richat Structure
The Richat Structure, also called ''Guelb er Richât'' ( ar, قلب الريشات, Qalb ar-Rīšāt), is a prominent circular geological feature in the Sahara's Adrar Plateau, near Ouadane, west–central Mauritania, Northwest Africa. In the local dialect, ''Richat'' means ''feather'' and it also is known locally in Arabic as ''tagense''. Tagense refers to the circular opening of the leather pouch used to draw water from local wells. It is an eroded geological dome, in diameter, exposing sedimentary rock in layers which appear as concentric rings. Igneous rock is exposed inside and there are spectacular rhyolites and gabbros which have undergone hydrothermal alteration, and a central megabreccia. The structure is also the location of exceptional accumulations of Acheulean archaeological artifacts. It was selected as one of the first 100 geological heritage sites identified by the International Union of Geological Sciences (IUGS) to be of the highest scientific value. De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adrar Plateau
The Adrar (, Berber for "mountain") is a highland natural and historical region of the Sahara Desert in northern Mauritania. The Adrar Region, an administrative division of Mauritania, is named after the traditional region. It is sometimes called Adrar Tamar to distinguish it from other areas called Adrar in the Sahara. Geography The Adrar is an arid plateau, known for its gorges, regs (stony deserts) and sand dunes. Structurally the Adrar is a low central massif which rises to over above sea level just east of Atar near the Amojjar Pass on the track to Chinguetti, then loses elevation and becomes subsumed by dunes to the south and east. Limited cultivation is only possible in the gorges at lower elevations such like oued Seguellil where the water table is high enough to support large palm groves. Notable features include the Oued el Abiod or 'White Valley', a dune-filled fault line along which many small settlements and palm groves are found. The Guelb Aouelloul crater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elliptical Dome
An elliptical dome, or an ''oval dome'', is a dome whose bottom cross-section takes the form of an ellipse. Technically, an ''ellipsoidal dome'' has a circular cross-section, so is not quite the same. While the cupola can take different geometries, when the ceiling's cross-section takes the form of an ellipse, and due to the reflecting properties of an ellipse, any two persons standing at a focus of the floor's ellipse can have one whisper, and the other hears; this is a whispering gallery. The largest elliptical dome in the world is at the Sanctuary of Vicoforte in Vicoforte, Italy. In architecture Elliptical domes have many applications in architecture; and are useful in covering rectangular spaces. The oblate, or horizontal elliptical dome is useful when there is a need to limit height of the space that would result from a spherical dome. As the mathematical description of an elliptical dome is more complex than that of spherical dome, design care is needed. In a geode ... [...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 atmosphere to fall back as 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 fails to crystallize at all, instead becoming a natural glass or obsidian. If the magma contains abundant 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 basalt. Other examples of extrusive rocks are rhyolite and andesite. Texture The texture ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrusive Rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusion, such as a volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grained plutonic rock (typically formed deeper in the Earth's crust in batholiths or stocks) an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chicoutimi
Chicoutimi () is the most populous borough (arrondissement) of the city of Saguenay in Quebec, Canada. It is situated at the confluence of the Saguenay and Chicoutimi rivers. During the 20th century, it became the main administrative and commercial centre of the Saguenay–Lac-Saint-Jean region. In 2002 it merged into the new city of Saguenay and forms the heart of the 5th-largest urban area of the province of Quebec. At the 2021 census, its population was 69,004. History What was ultimately to become the centre of the borough of Chicoutimi was first settled by French colonists in 1676 as a trading post in the fur trade. At that time, the Saguenay and the Chicoutimi rivers had been used as waterways by the Montagnais tribes for centuries. The name ''Chicoutimi'' means ''the end of the deep water'' in the Innu language. After the British seized Lower Canada, the Chicoutimi trading post continued to operate only until 1782, as the fur trade had moved further west of the Gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Université Du Québec à Chicoutimi
The Université du Québec à Chicoutimi (UQAC) is a branch of the Université du Québec network founded in 1969 and based in the Chicoutimi borough of Saguenay, Quebec, Canada. UQAC has secondary study centres in La Malbaie, Saint-Félicien, Alma, and Sept-Îles. In 2017, 7500 students were registered and 209 professors worked for the university, making it the fourth largest of the ten Université du Québec branches, after Université du Québec à Montréal (UQAM), Université du Québec à Trois-Rivières (UQTR), and École de technologie supérieure (ETS). Academics It offers over forty undergraduate and graduate programs. The university is especially well known for its researchers in aluminium (with two research centres), forestry, icing (in French, givrage), geology and historical population studies. In 2005, UQAC opened programs for students from foreign countries in partnership with universities from Morocco, Lebanon, China, Senegal, Colombia, and Brazil. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breccia
Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia, and hydrothermal breccia. A megabreccia is a breccia composed of very large rock fragments, sometimes kilometers across, which can be formed by landslides, impact events, or caldera collapse. Types Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. These indicate that the gravel was deposited very close to its source area, since other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Dioxide
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as a synthetic product. Notable examples include fused quartz, fumed silica, silica gel, opal and aerogels. It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries. Structure In the majority of silicates, the silicon atom shows tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. In contrast, CO2 is a linear molecule. The starkly different structures of the d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuesta
A cuesta (from Spanish ''cuesta'' "slope") is a hill or ridge with a gentle slope on one side, and a steep slope on the other. In geology the term is more specifically applied to a ridge where a harder sedimentary rock overlies a softer layer, the whole being tilted somewhat from the horizontal. This results in a long and gentle backslope called a dip slope that conforms with the dip of resistant strata, called caprock. Where erosion has exposed the frontslope of this, a steep slope or escarpment occurs. The resulting terrain may be called scarpland. Definition In general usage, a cuesta is a hill or ridge with a gentle slope (backslope) on one side, and a steep slope (frontslope) on the other. The word is from Spanish: "flank or slope of a hill; hill, mount, sloping ground". In geology and geomorphology, cuesta refers specifically to an asymmetric ridge with a long and gentle backslope called a dip slope that conforms with the dip of a resistant stratum or strata, called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals. The term ''quartzite'' is also sometimes used for very hard but unmetamorphosed sandstones that are composed of quartz grains thoroughly cemented with additional quartz. Such sedimentary rock has come to be described as orthoquartzite to distinguish it from metamorphic quartzite, which is sometimes called metaquartzite to emphasize its metamorphic origins. Quartzite is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strike And Dip
Strike and dip is a measurement convention used to describe the orientation, or attitude, of a planar geologic feature. A feature's strike is the azimuth of an imagined horizontal line across the plane, and its dip is the angle of inclination measured downward from horizontal. They are used together to measure and document a structure's characteristics for study or for use on a geologic map. A feature's orientation can also be represented by dip and dip direction, using the azimuth of the dip rather than the strike value. Linear features are similarly measured with trend and plunge, where "trend" is analogous to dip direction and "plunge" is the dip angle. Strike and dip are measured using a compass and a clinometer. A compass is used to measure the feature's strike by holding the compass horizontally against the feature. A clinometer measures the features dip by recording the inclination perpendicular to the strike. These can be done separately, or together using a tool such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur as dissolved minerals precipitate from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
