A peninsula is a landform surrounded by water on the majority of its border while being connected to a mainland from which it extends. The surrounding water is understood to be continuous, though not named as a single body of water. Peninsulas are not always named as such. A point is considered a tapering piece of land projecting into a body of water, less prominent than a cape. A river which courses through a tight meander is sometimes said to form a "peninsula" within the loop of water. In English, the plural versions of peninsula are peninsulas and, less peninsulae. List of peninsulas Isthmus
Nepheline called nephelite, is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, in their associated pegmatites. Nepheline crystals are rare and belong to the hexagonal system having the form of a short, six-sided prism terminated by the basal plane; the unsymmetrical etched figures produced artificially on the prism faces indicate, that the crystals are hemimorphic and tetartohedral, the only element of symmetry being a polar hexad axis. It is found in compact, granular aggregates, can be white, gray, green, or reddish; the hardness is 5.5 – 6, the specific gravity 2.56 – 2.66. It is translucent with a greasy luster; the low index of refraction and the feeble double refraction in nepheline are nearly the same as in quartz. An important determinative character of nepheline is the ease with which it is decomposed by hydrochloric acid, with separation of gelatinous silica and cubes of salt. For this reason, a clear crystal of nepheline becomes cloudy.
Although sodium and potassium are always present in occurring nepheline in the atomic ratio, artificially prepared crystals have the composition NaAlSiO4. It has therefore been suggested that the orthosilicate formula, AlSiO4, represents the true composition of nepheline; the mineral is one liable to alteration, in the laboratory various substitution products of nepheline have been prepared. In nature it is altered to zeolites, kaolin, or compact muscovite. Gieseckite and liebenerite are pseudomorphs. Two varieties of nepheline are distinguished, differing in their external appearance and in their mode of occurrence, being analogous in these respects to sanidine and common orthoclase respectively. Glassy nepheline has the form of small, transparent crystals and grains with a vitreous luster, it is characteristic of the volcanic rocks rich in alkalis, such as phonolite, nepheline-basalt, leucite basalt, etc. and of certain dike-rocks, such as tinguaite. The best crystals occur with mica, garnet, etc. in the crystal-lined cavities of the ejected blocks of Monte Somma, Vesuvius.
The other variety, known as elaeolite, occurs as large, rough crystals, or more as irregular masses, which have a greasy luster and are opaque, or at most translucent, with a reddish, brownish or grey color. It forms an essential constituent of certain alkaline plutonic rocks of the nepheline syenite series, which are developed in southern Norway; the color and greasy luster of elaeolite are due to the presence of numerous microscopic enclosures of other minerals augite or hornblende. These enclosures sometimes give rise to a chatoyant effect like that of cymophane; this article incorporates text from a publication now in the public domain: Leonard James Spencer. "Nepheline". In Chisholm, Hugh. Encyclopædia Britannica. Cambridge University Press. Media related to Nepheline at Wikimedia Commons
Kukisvumchorr is a mountain part of the Khibiny Mountains mountain range in Russia. It is located near the centre of the range; the summit is stony, while the sides are covered with tundra vegetation. The mountain has an notable for its composition of nepheline syenite. Apatite is mined from the area; the nearby Kukisvumchorr Microdistrict shares the same name as the mountain. An earthquake occurred on 21 October 2010 of magnitude 3.2.
The Lovozero Massif is a mountain range located in the center of the Kola Peninsula in Russia, between Lovozero and Lake Umbozero, constitutes a horseshoe-shaped ridge of picturesque hills, that surround the Seydozero Lake. The slopes are covered with spruce and pine; the highest point is Mount Angvundaschorr. The area around the lake is inhabited by Saami, many place names are of non-Russian origin; the Lovozero Massif is underlain by a complex of agpaitic to hyperagpaitic rocks containing minerals as eudialyte, natrosilite, etc. At least 105 valid minerals have been described in the massif and 39 minerals were discovered there; the only other areas with similar geology and mineralogy are Khibiny Massif, Ilimaussaq in SW Greenland and Mont-Saint-Hilaire, Canada. The area is well accessible from railroads. In winter the area is accessible from Khibiny Mountains via the ice of Umbozero. In summer there are usable mountain trails. Ilma Puncha Motka Lovozero Umbozero Seidozero Sengisyavr Rayavr Motka Bay Ilmayok Elmorayok Seidyok Kiftuay Kitkuay Uelkuay Sigsuay Tavayok Muruay Chivruay Kuansuay Iidichyok Vavnyok Koklukhtiuay Alluayv Angvundaschorr Sengischorr Mannepakhk Elmorayok Pass Kuftuay Pass Chivruay-Ladv Pass Strashempakhk Engpor Suoluayv Punkaruayv Ninchurt Mount Karnasurta Mount Kuyvchorr Mount Kuamdespakhk Mount Vavnbed References: Pekov, Igor: Lovozero Massif Vneshtorgizdat Publishing Moscow 2000 Khomyakov, A. P.: Mineralogy of Hyperagpaitic Alkaline Rocks Clarendon Press 1995 Lovozero Tundras, In Russian Geology and minerals
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, alpine tundra merges with polar tundra; the high elevation causes an adverse climate, too cold and windy to support tree growth. Alpine tundra transitions to sub-alpine forests below the tree line. With increasing elevation it ends at the snow line where ice persist through summer. Alpine tundra occurs in mountains worldwide; the flora of the alpine tundra is characterized by dwarf shrubs close to the ground. The cold climate of the alpine tundra is caused by adiabatic cooling of air, is similar to polar climate. Alpine tundra occurs at high enough altitude at any latitude. Portions of montane grasslands and shrublands ecoregions worldwide include alpine tundra. Large regions of alpine tundra occur in the North American Cordillera, the Alps and Pyrenees of Europe, the Himalaya and Karakoram of Asia, the Andes of South America, the Eastern Rift mountains of Africa.
Alpine tundra occupies high-mountain summits and ridges above timberline. Aspect plays a role as well; because the alpine zone is present only on mountains, much of the landscape is rugged and broken, with rocky, snowcapped peaks and talus slopes, but contains areas of rolling to flat topography. Averaging over many locations and local microclimates, the treeline rises 75 metres when moving 1 degree south from 70 to 50°N, 130 metres per degree from 50 to 30°N. Between 30°N and 20°S, the treeline is constant, between 3,500 and 4,000 metres. Alpine climate is the average weather for the alpine tundra; the climate becomes colder at high elevations—this characteristic is described by the lapse rate of air: air tends to get colder as it rises, since it expands. The dry adiabatic lapse rate is 10 °C per km of altitude. Therefore, moving up 100 metres on a mountain is equivalent to moving 80 kilometers towards the pole; this relationship is only approximate, since local factors such as proximity to oceans can drastically modify the climate.
Typical high-elevation growing seasons range from 45 to 90 days, with average summer temperatures near 10 °C. Growing season temperatures fall below freezing, frost occurs throughout the growing season in many areas. Precipitation occurs as winter snow, but soil water availability is variable with season and topography. For example, snowfields accumulate on the lee sides of ridges while ridgelines may remain nearly snow free due to redistribution by wind; some alpine habitats may be up to 70% snow free in winter. High winds are common in alpine ecosystems, can cause significant soil erosion and be physically and physiologically detrimental to plants. Wind coupled with high solar radiation can promote high rates of evaporation and transpiration. There have been several attempts at quantifying. Climatologist Wladimir Köppen demonstrated a relationship between the Arctic and Antarctic tree lines and the 10 °C summer isotherm. See Köppen climate classification for more information. Otto Nordenskiöld theorized that winter conditions play a role: His formula is W = 9 − 0.1 C, where W is the average temperature in the warmest month and C the average of the coldest month, both in degrees Celsius.
In 1947, Holdridge improved on these schemes, by defining biotemperature: the mean annual temperature, where all temperatures below 0 °C are treated as 0 °C. If the mean biotemperature is between 1.5 and 3 °C, Holdridge quantifies the climate as alpine. Because the habitat of alpine vegetation is subject to intense radiation, cold and ice, it grows close to the ground and consists of perennial grasses and forbs. Perennial herbs dominate the alpine landscape; the roots and rhizomes not only function in water and nutrient absorption but play a important role in over-winter carbohydrate storage. Annual plants are rare in this ecosystem and are only a few inches tall, with weak root systems. Other common plant life-forms include prostrate shrubs, graminoids forming tussocks, cushion plants, cryptogams, such as bryophytes and lichens. Relative to lower elevation areas in the same region, alpine regions have a high rate of endemism and a high diversity of plant species; this taxonomic diversity can be attributed to geographical isolation, climate changes, microhabitat differentiation, different histories of migration or evolution or both.
These phenomena contribute to plant diversity by introducing new flora and favoring adaptations, both of new species and the dispersal of pre-existing species. Plants have adapted to the harsh alpine environment. Cushion plants, looking like ground-hugging clumps of moss, escape the strong winds blowing a few inches a
A glacier is a persistent body of dense ice, moving under its own weight. Glaciers deform and flow due to stresses induced by their weight, creating crevasses and other distinguishing features, they abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges on every continent including Oceania's high-latitude oceanic island countries such as New Zealand and Papua New Guinea. Between 35°N and 35°S, glaciers occur only in the Himalayas, Rocky Mountains, a few high mountains in East Africa, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earth's land surface. Continental glaciers cover nearly 13 million km2 or about 98 percent of Antarctica's 13.2 million km2, with an average thickness of 2,100 m.
Greenland and Patagonia have huge expanses of continental glaciers. Glacial ice is the largest reservoir of fresh water on Earth. Many glaciers from temperate and seasonal polar climates store water as ice during the colder seasons and release it in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source, important for plants and human uses when other sources may be scant. Within high-altitude and Antarctic environments, the seasonal temperature difference is not sufficient to release meltwater. Since glacial mass is affected by long-term climatic changes, e.g. precipitation, mean temperature, cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level. A large piece of compressed ice, or a glacier, appears blue, as large quantities of water appear blue; this is. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing the density of the created ice.
The word glacier is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, Latin glaciēs, meaning "ice". The processes and features caused by or related to glaciers are referred to as glacial; the process of glacier establishment and flow is called glaciation. The corresponding area of study is called glaciology. Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, behavior. Cirque glaciers form on the slopes of mountains. A glacier that fills a valley is called a valley glacier, or alternatively an alpine glacier or mountain glacier. A large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have an area less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called continental glaciers. Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces.
The only extant ice sheets are the two that cover most of Greenland. They contain vast quantities of fresh water, enough that if both melted, global sea levels would rise by over 70 m. Portions of an ice sheet or cap that extend into water are called ice shelves. Narrow, fast-moving sections of an ice sheet are called ice streams. In Antarctica, many ice streams drain into large ice shelves; some drain directly into the sea with an ice tongue, like Mertz Glacier. Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica and Ellesmere Islands in Canada, Southeast Alaska, the Northern and Southern Patagonian Ice Fields; as the ice reaches the sea, pieces break off, or calve. Most tidewater glaciers calve above sea level, which results in a tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by the climate change than those of other glaciers.
Thermally, a temperate glacier is at melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below the freezing point from the surface to its base, although the surface snowpack may experience seasonal melting. A sub-polar glacier includes both temperate and polar ice, depending on depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is described by its basal temperature. A cold-based glacier is below freezing at the ice-ground interface, is thus frozen to the underlying substrate. A warm-based glacier is above or at freezing at the interface, is able to slide at this contact; this contrast is thought to a large extent to govern the ability of a glacier to erode its bed, as sliding ice promotes plucking at rock from the surface below. Glaciers which are cold-based and warm-based are known as polythermal. Glaciers form where the accumulation of ice exceeds ablation. A glacier originates from a landform called'cirque' – a armchair-shaped geological feature (such as a depressio
Snowfield is a former name of the UK indie rock band Editors A snow field, snowfield or neve is an accumulation of permanent snow and ice found above the snow line in mountainous and glacial terrain. Glaciers originate in snowfields; the lower end of a glacier is free from snow and névé in summer. In the upper end and above the upper boundary of a glacier, the snow field is an ice field covered with snow; the glacier upper boundary, where it emerges from under a snow field, is ill-defined because of gradual transition