Gneiss is a common distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks. The foliations are characterized by alternating darker and lighter colored bands, the word gneiss comes from the Middle High German verb gneist. It has occurred in English since at least 1757, gneissic rocks are usually medium- to coarse-foliated, they are largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals. Gneisses that are metamorphosed igneous rocks or their equivalent are termed granite gneisses, diorite gneisses, gneiss rocks may be named after a characteristic component such as garnet gneiss, biotite gneiss, albite gneiss, etc. Orthogneiss designates a gneiss derived from a rock, and paragneiss is one from a sedimentary rock. Gneissose rocks have properties similar to gneiss, gneiss appears to be striped in bands, called gneissic banding. The banding is developed under high temperature and pressure conditions, the minerals are arranged into layers that appear as bands in cross section.
The appearance of layers, called compositional banding, occurs because the layers, the darker bands have relatively more mafic minerals. The lighter bands contain relatively more felsic and these forces stretch out the rock like a plastic, and the original material is spread out into sheets. Another cause of banding is metamorphic differentiation, which separates different materials into different layers through chemical reactions, not all gneiss rocks have detectable banding. In kyanite gneiss, crystals of kyanite appear as random clumps in what is mainly a plagioclase matrix, henderson gneiss is found in North Carolina and South Carolina, US, east of the Brevard Shear Zone. It has deformed into two sequential forms, the second, more warped, form is associated with the Brevard Fault, and the first deformation results from displacement to the southwest. Most of the Outer Hebrides of Scotland have a formed from Lewisian gneiss. In addition to the Outer Hebrides, they form basement deposits on the Scottish mainland west of the Moine Thrust and on the islands of Coll and Tiree.
These rocks are igneous in origin, mixed with metamorphosed marble and mica schist with intrusions of basaltic dikes. Gneisses of Archean and Proterozoic age occur in the Baltic Shield, in antiquity, gneisses were utilized in architectural construction. They were used to erect the Sphinx of Taharqo in the Nile Valley, list of rock types Blatt and Robert J. Tracy. Petrology, Igneous and Metamorphic, 2nd ed. Freeman, mcKirdy, Roger Crofts and John Gordon
Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Granites can be white, pink, or gray in color. The word granite comes from the Latin granum, a grain, in reference to the structure of such a holocrystalline rock. By definition, granite is a rock with at least 20% quartz. The term granitic means granite-like and is applied to granite and a group of igneous rocks with similar textures and slight variations in composition. Occasionally some individual crystals are larger than the groundmass, in case the texture is known as porphyritic. A granitic rock with a texture is known as a granite porphyry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks, petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of granite is rhyolite, Granite is nearly always massive and tough, and therefore it has gained widespread use throughout human history, and more recently as a construction stone.
The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength usually lies above 200 MPa, and its viscosity near STP is 3–6 •1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C, it is reduced in the presence of water. Granite has poor primary permeability, but strong secondary permeability, true granite according to modern petrologic convention contains both plagioclase and alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite, when a granitoid contains less than 10% orthoclase, it is called tonalite and amphibole are common in tonalite. A granite containing both muscovite and biotite micas is called a binary or two-mica granite, two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites. A worldwide average of the composition of granite, by weight percent, based on 2485 analyses. Much of it was intruded during the Precambrian age, it is the most abundant basement rock that underlies the relatively thin veneer of the continents.
Outcrops of granite tend to form tors and rounded massifs, granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite often occurs as small, less than 100 km² stock masses
A ridge or mountain ridge is a geological feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance. Ridges are usually termed hills or mountains as well, depending on size, there are several main types of ridges, Dendritic ridge, In typical dissected plateau terrain, the stream drainage valleys will leave intervening ridges. These are by far the most common ridges and these ridges usually represent slightly more erosion resistant rock, but not always – they often remain because there were more joints where the valleys formed, or other chance occurrences. This type of ridge is somewhat random in orientation, often changing direction frequently. Similar ridges have formed in such as the Black Hills. Sometimes these ridges are called hogback ridges, oceanic spreading ridge, In tectonic spreading zones around the world, such as at the Mid-Atlantic Ridge, the volcanic activity forming new plate boundary forms volcanic ridges at the spreading zone.
Isostatic settling and erosion gradually reduce the moving away from the zone. Crater ridges, Large meteorite strikes typically form large impact craters bordered by circular ridges, volcanic crater/caldera ridges, Large volcanoes often leave behind a central crater/caldera bordered by circular ridges. Fault ridges, Faults often form escarpments, sometimes the tops of the escarpments form not plateaus, but slope back so that the edges of the escarpments form ridges. Dune ridges, In areas of large-scale dune activity, certain types of dunes result in sand ridges and eskers, Glacial activity may leave ridges in the form of moraines and eskers. An arête is a ridge of rock that is formed by glacial erosion. Volcanic subglacial ridges, Many subglacial volcanoes create ridge-like formations when lava erupts through a glacier or ice sheet. Shutter ridges, A shutter ridge is a ridge which has moved along a fault line, typically, a shutter ridge creates a valley corresponding to the alignment of the fault that produces it
The French Alps are the portions of the Alps mountain range that stand within France, located in the Rhône-Alpes and Provence-Alpes-Côte dAzur regions. While some of the ranges of the French Alps are entirely in France, others, at 4,808 metres, Mont Blanc, on the French-Italian border, is the highest mountain in the Alps, and the highest Western European mountain. Notable towns in the French Alps include Grenoble, Annecy, Chambéry, Évian-les-Bains, the largest connected ski areas are, Les Trois Vallées,338 slopes,600 km of pistes. Portes du Soleil,288 slopes,650 km of slopes not entirely connected, Champagny-en-Vanoise,239 slopes,420 km of slopes. Via Lattea,214 slopes,400 km of slopes, Évasion Mont-Blanc,183 slopes,420 km of slopes not entirely connected. Espace Killy,137 slopes,300 km of slopes, grand Massif,134 slopes,265 km of slopes. Les Aravis,133 slopes,220 km of slopes not entirely connected, Les Grandes Rousses,117 slopes,236 km of slopes. Serre Chevalier,111 slopes,250 km of slopes, La Forêt Blanche,104 slopes,180 km of slopes.
Les Sybelles,96 slopes,310 km of slopes and Valmeinier,83 slopes,150 km of slopes. Grand Domaine,82 slopes,150 km of slopes Espace San Bernardo,73 slopes,150 km of slopes, Les Deux Alpes and La Grave,69 slopes,220 km of slopes. The other large ski areas are, Le Val dArly,150 km of slopes, in the winter, these include skiing and snowboarding as well as alternatives such as snowshoeing, sledging. There is a range of activities that happen such as gliding which most happens during the summer months. Summer activities include hiking, mountaineering and rock climbing, roger Frison-Roche, Les montagnes de la terre. Sergio Marazzi, Atlante Orografico delle Alpi, pavone Canavese, Priuli & Verlucca editori. ISBN 978-88-8068-273-8 Sergio Marazzi, La Suddivisione orografica internazionale unificata del Sistema Alpino - article with maps and illustrations, PDF
Hautes-Alpes is a department in southeastern France named after the Alps mountain range. Hautes-Alpes is one of the original 83 departments created during the French Revolution on 4 March 1790 and it consists of the southeast of the former province of Dauphiné and the north of Provence. Napoleon passed through Gap when he returned to reclaim France after his exile on Elba using what is now known as Route Napoléon, the department is surrounded by the following French departments, Alpes-de-Haute-Provence, Drôme, Isère, and Savoie. Italy borders it on the east, hautes-Alpes is located in the Alps mountain range. The average elevation is over 1000 m, and the highest elevation is over 4000 m, the only three sizable towns are Gap, Briançon, and Embrun, which was the subprefecture until 1926. The third highest commune in all of Europe is the village of Saint-Véran and Briançon are the highest prefecture and subprefecture in France. The Queyras valley is located in the part of the department and is noted by many as being an area of outstanding beauty.
The inhabitants of the department are called Haut-Alpins, the extremely mountainous terrain explains the sparse population, which was originally about 120,000. It changed little during the 19th century, but fell to about 85,000 after World War I, thanks in large part to tourism, the population has risen from 87,436 in 1962 to 121,419 in 1999, principally in the town of Gap. The President of the General Council is Jean-Yves Dusserre of the Union for a Popular Movement, the tourist industry is largely dependent on skiing in winter. In summer the Alpine scenery and many activities attract visitors from across Europe. The Tour de France passes through the department regularly and this draws many cycling fanatics to cycle the cols and watch the race
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a maximum in elevation. The topographic terms acme, apex and zenith are synonymous, the UIAA definition is that a summit is independent if it has a prominence of 30 metres or more, it is a mountain if it has a prominence of at least 300 metres. This can be summarised as follows, A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top, Summit may refer to the highest point along a line, trail, or route. In many parts of the western United States, the term refers to the highest point along a road, highway. For example, the highest point along Interstate 80 in California is referred to as Donner Summit while the highest point on Interstate 5 is Siskiyou Mountain Summit, geoid Hill List of highest mountains Maxima and minima Nadir Summit accordance Peak finder
Chamonix-Mont-Blanc, more commonly known as Chamonix, is a commune in the Haute-Savoie département in the Auvergne-Rhône-Alpes region in south-eastern France. It was the site of the first Winter Olympics in 1924, the communes population of around 8,900 ranks 1, 089th within the country of France. The north side of the summit of Mont Blanc, and therefore the summit itself are part of the village of Chamonix, to the south side, the situation is different depending on the country. Italy considers that the passes through the top. France considers that the runs along the rocky Tournette under the summit cap. The south side was in France, assigned to the commune of Saint-Gervais-les-Bains sharing the summit with its neighbor Chamonix and it is this situation for France, which is found on the French IGN maps. With an area of 245 km2, Chamonix is the fourth largest commune in mainland France, however, in 1786 the inhabitants bought their freedom from the canons of Sallanches, to whom the priory had been transferred in 1519.
In 1530, the inhabitants obtained from the Count of the Genevois the privilege of holding two fairs a year, while the valley was visited by the civil officials and by the bishops of Geneva. But travellers for pleasure were very rare, the first party to publish an account of their visit was that of Dr. Richard Pococke, Mr. William Windham and others, such as the Englishmen who visited the Mer de Glace in 1741. In 1742 came P. Martel and several other Genevese, in 1760 H. B. de Saussure, the commune successfully lobbied to change its name from Chamonix to Chamonix-Mont-Blanc in 1916. The holding of the first Winter Olympic Games in Chamonix in 1924 further raised Chamonixs profile as an international tourist destination, during the Second World War, a Childrens Home operated in Chamonix, in which several dozens of Jewish children were hidden from the Nazis. Some of their saviors were recognised as Righteous Among the Nations, the commune of Chamonix-Mont-Blanc includes 16 villages and hamlets. Chamonix has a climate, between oceanic and humid continental climate, with an average annual precipitation of 1,275 mm.
Summers are mild and winters are cold and snowy, Population Change Sources, Ldh/EHESS/Cassini until 1962, INSEE database from 1968 · Population Over Time Chamonix is a winter sports resort town. As the highest European mountain west of Russia, Mont Blanc attracts mountain climbers, there is a cable car up to the 3,842 m Aiguille du Midi. Constructed in 1955, it was the highest cable car in the world, the town of Chamonix is served by French Route Nationale 205, nicknamed the Route blanche, or white route, due to its snowiness. This is an extension of French autoroute 40, similarly nicknamed the autoroute blanche, which ends at Le Fayet, the 11. 6-km Mont Blanc Tunnel originates here, linking Chamonix to Courmayeur in Italy. Chamonix is linked to Switzerland by what used to be RN 506a, in 2006, it was converted to a Route Départementale 1506, with a part of it integrated into RN205
Savoy is a cultural region in Western Europe. It comprises roughly the territory of the Western Alps between Lake Geneva in the north and Dauphiné in the south, the historical land of Savoy emerged as the feudal territory of the House of Savoy during the 11th to 14th centuries. The historical territory is shared between the countries of France and Switzerland. Installed by Rudolph III, King of Burgundy, officially in 1003 and it ruled the County of Savoy to 1416 and the Duchy of Savoy from 1416 to 1860. The territory of Savoy was annexed to France in 1792 under the French First Republic, victor Emmanuels dynasty, the House of Savoy, retained its Italian lands of Piedmont and Liguria and became the ruling dynasty of Italy. In modern France, Savoy is part of the Auvergne-Rhône-Alpes region, following its annexation to France in 1860, the territory of Savoy was divided administratively into two separate departments and Haute-Savoie. The traditional capital remains Chambéry, on the rivers Leysse and Albane, hosting the castle of the House of Savoy, the capital of the Duchy remained at the traditional Savoyard capital of Chambéry until 1563, when it was moved to Turin.
The region was occupied by the Allobroges, a Celtic people that in 121 BC were subdued by the Roman Empire, the name Savoy stems from the Late Latin Sapaudia, referring to a fir forest. It is first recorded in Ammianus Marcellinus, to describe the part of Maxima Sequanorum. According to the Gallic Chronicle of 452, it was separated from the rest of Burgundian territories in 443 and this latter territory comprised what would become known as Savoy and Provence. From the 10th to 14th century, parts of what would ultimately become Savoy remained within the Kingdom of Arles. Beginning in the 11th century, the rise to power of the House of Savoy is reflected in the increasing territory of their County of Savoy between 1003 and 1416. The County of Savoy was detached de jure from the Kingdom of Arles by Emperor Charles IV in 1361, on February 19,1416, Holy Roman Emperor, made the County of Savoy an independent duchy, with Amadeus VIII as the first duke. Straddling the Alps, Savoy lay within two competing spheres of influence, a French sphere and a North Italian one, at the time of the Renaissance, Savoy showed only modest development.
Its towns were few and small, Savoy derived its subsistence from agriculture. The geographic location of Savoy was of military importance, during the interminable wars between France and Spain over the control of northern Italy, Savoy was important to France because it provided access to Italy. Savoy was important to Spain because it served as a buffer between France and the Spanish held lands in Italy, in 1563 Emmanuel Philibert moved the capital from Chambéry to Turin, which was less vulnerable to French interference. Vaud was annexed by Bern in 1536, and Savoy officially ceded Vaud to Bern in the Treaty of Lausanne of 30 October 1564
Feldspars are a group of rock-forming tectosilicate minerals that make up about 40% of the Earths continental crust. Feldspars crystallize from magma as veins in both intrusive and extrusive rocks and are present in many types of metamorphic rock. Rock formed almost entirely of plagioclase feldspar is known as anorthosite. Feldspars are found in types of sedimentary rocks. The name feldspar derives from the German Feldspat, a compound of the words Feld and Spat, the change from Spat to -spar was influenced by the English word spar, a synonym for mineral. Feldspathic refers to materials that contain feldspar, the alternate spelling, has largely fallen out of use. This group of minerals consists of tectosilicates, solid solutions between albite and anorthite are called plagioclase, or more properly plagioclase feldspar. Only limited solid solution occurs between K-feldspar and anorthite, and in the two solid solutions, immiscibility occurs at temperatures common in the crust of the earth. Albite is considered both a plagioclase and alkali feldspar, the alkali feldspars are as follows, orthoclase —KAlSi3O8 sanidine —AlSi3O8 microcline —KAlSi3O8 anorthoclase —AlSi3O8 Sanidine is stable at the highest temperatures, and microcline at the lowest.
Perthite is a texture in alkali feldspar, due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition. The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye, microperthitic textures in crystals are visible using a light microscope, whereas cryptoperthitic textures can be seen only with an electron microscope. Barium feldspars are considered alkali feldspars, barium feldspars form as the result of the substitution of barium for potassium in the mineral structure. The barium feldspars are monoclinic and include the following, celsian—BaAl2Si2O8 hyalophane—4O8 The plagioclase feldspars are triclinic, the immiscibility gaps in the plagioclase solid solutions are complex compared to the gap in the alkali feldspars. The play of colours visible in some feldspar of labradorite composition is due to very fine-grained exsolution lamellae, chemical weathering of feldspars results in the formation of clay minerals.
About 20 million tonnes of feldspar were produced in 2010, mostly by three countries, Italy and China, Feldspar is a common raw material used in glassmaking, and to some extent as a filler and extender in paint and rubber. In glassmaking, alumina from feldspar improves product hardness, durability, in ceramics, the alkalis in feldspar act as a flux, lowering the melting temperature of a mixture. Fluxes melt at a stage in the firing process, forming a glassy matrix that bonds the other components of the system together. In the US, about 66% of feldspar is consumed in glassmaking, including glass containers and other uses, such as fillers, accounted for the remainder