Hamada Elwan
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Hamada Elwan
A hamada (, ) is a type of desert landscape consisting of high, largely barren, hard rocky (basalt) plateaus, where most of the sand has been removed by deflation. The majority of the Sahara is hamada. Other examples are Negev desert in Israel and the in Algeria. Formation Hamadas are produced by the wind, which removes the fine products of weathering, an aeolian process known as deflation. The finer-grained products are taken away in suspension. At the same time, the sand is removed through saltation and surface creep, leaving behind a landscape of gravel, boulders and bare rock. Related landforms Hamada is related to desert pavement (known variously as reg, serir, gibber, or saï), which occurs as stony plains or depressions covered with gravels or boulders rather than as highland plateaus. Hamadas exist in contrast to ''ergs'', which are large areas of shifting sand dunes.McKnight, Tom L. and Darrel Hess. ''Physical Geography: A Landscape Appreciation'', 8th ed., pp. ...
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La Hamada Noire Du Tademayt 1890
LA most frequently refers to Los Angeles, the second most populous city in the United States of America. La, LA, or L.A. may also refer to: Arts and entertainment Music * La (musical note), or A, the sixth note *"L.A.", a song by Elliott Smith on ''Figure 8'' (album) * ''L.A.'' (EP), by Teddy Thompson *'' L.A. (Light Album)'', a Beach Boys album * "L.A." (Neil Young song), 1973 *The La's, an English rock band * L.A. Reid, a prominent music producer * Yung L.A., a rapper *Lady A, an American country music trio * "L.A." (Amy Macdonald song), 2007 *"La", a song by Australian-Israeli singer-songwriter Old Man River *''La'', a Les Gordon album Other media * l(a, a poem by E. E. Cummings * La (Tarzan), fictional queen of the lost city of Opar (Tarzan) *'' Lá'', later known as Lá Nua, an Irish language newspaper * La7, an Italian television channel *LucasArts, an American video game developer and publisher * Liber Annuus, academic journal Business, organizations, and governmen ...
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Saltation (geology)
In geology, saltation () is a specific type of particle transport by fluids such as wind or water. It occurs when loose materials are removed from a bed and carried by the fluid, before being transported back to the surface. Examples include pebble transport by rivers, sand drift over desert surfaces, soil blowing over fields, and snow drift over smooth surfaces such as those in the Arctic or Canadian Prairies. Process At low fluid velocities, loose material rolls downstream, staying in contact with the surface. This is called ''creep'' or ''reptation''. Here the forces exerted by the fluid on the particle are only enough to roll the particle around the point of contact with the surface. Once the wind speed reaches a certain critical value, termed the ''impact'' or ''fluid threshold'', the drag and lift forces exerted by the fluid are sufficient to lift some particles from the surface. These particles are accelerated by the fluid, and pulled downward by gravity, causing them t ...
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Amaranthaceae
Amaranthaceae ( ) is a family of flowering plants commonly known as the amaranth family, in reference to its type genus '' Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making it the most species-rich lineage within its parent order, Caryophyllales. Description Most species in the Amaranthaceae are annual or perennial herbs or subshrubs; others are shrubs; very few species are vines or trees. Some species are succulent. Many species have stems with thickened nodes. The wood of the perennial stem has a typical "anomalous" secondary growth; only in subfamily Polycnemoideae is secondary growth normal. The leaves are simple and mostly alternate, sometimes opposite. They never possess stipules. They are flat or terete, and their shape is extremely variable, with entire or toothed margins. In some species, the leaves are reduced to minute scales. In most cases, neither basal nor terminal aggregations of leav ...
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Hammada (plant)
''Hammada'' is a genus of flowering plants belonging to the family Amaranthaceae, in which it is placed in the subfamily Salsoloideae. It is a very unclear and unsorted genus, with many species that have been classed as synonyms by other authors. The native range of the genus is in central and southwestern Asia, with species found in Iraq, Lebanon, Palestine, Syria, Turkey and Uzbekistan. They are often found growing in alkaline or saline habitats. Description They are perennial plants, with a glabrous (smooth) wood (only at the base). They can grow up to tall. Michael Zohary The weed-like plants have regular, minute, or small, cyclic flowers. The flowers have no petals, but 5 sepals which are united at the base. It has 5 stamens and the ovary is positioned superior and consists of 2 united carpels. Which late matures into a fruit (or seed capsule). Known species According to Plants of the World Online; * '' Hammada eriantha'' Botsch. (from Uzbekistan) * '' Hammada ramosissima ...
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Sand Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called '' ergs'' or ''sand seas''. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter ''slip face'' in the lee side. The valley or trough between dunes is called a ''dune slack''. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation that would otherwise interfere with the development of dunes. However, sand deposits are not restricted to deserts, and dunes are also found along sea shores, along streams in semiarid climates, in areas of glacial outwash, and in other areas where poorly cemented san ...
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Erg (landform)
An erg (also sand sea or dune sea, or sand sheet if it lacks dunes) is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. The word is derived from the Arabic language, Arabic word ''ʿirq'' (), meaning "dune field". Strictly speaking, an erg is defined as a desert area that contains more than of aeolian processes, aeolian or wind-blown sand and where sand covers more than 20% of the surface. Smaller areas are known as "dune fields". The largest hot desert in the world, the Sahara, covers and contains several ergs, such as the Chech Erg and the Issaouane Erg in Algeria. Approximately 85% of all the Earth's mobile sand is found in ergs that are greater than , the largest being the Rub' al Khali, the ''Empty Quarter'' of the Arabian Peninsula. Ergs are also found on other celestial bodies, such as Venus, Mars, and Saturn's moon Titan (moon), Titan. Geography Sand seas and dune fields generally occur in regions downwind of copious sourc ...
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Desert Pavement
A desert pavement, also called reg (in western Sahara), serir (in eastern Sahara), gibber (in Australia), or saï (in central Asia) is a desert surface covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size. They typically top alluvial fans. Desert varnish collects on the exposed surface rocks over time. Geologists debate the mechanics of pavement formation and their age. Formation Several theories have been proposed for the formation of desert pavements. A common theory suggests that they form through the gradual removal of sand, dust and other fine-grained material by the wind and intermittent rain, leaving the larger fragments behind. The larger fragments are shaken into place through the forces of rain, running water, wind, gravity, creep, thermal expansion and contraction, wetting and drying, frost heaving, animal traffic, and the Earth's constant microseismic vibrations. The removal of small particles by wind does not co ...
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Boulder
In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to move. Smaller boulders are usually just called rocks or stones. Etymology The word ''boulder'' derives from ''boulder stone'', from Middle English ''bulderston'' or Swedish ''bullersten''.boulder. (n.d.)
Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website.


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Gravel
Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gravel is classified by grain size, particle size range and includes size classes from granule (geology), granule- to boulder-sized fragments. In the grain size, Udden-Wentworth scale gravel is categorized into granular gravel () and pebble gravel (). ISO 14688 grades gravels as fine, medium, and coarse, with ranges for fine and for coarse. One cubic metre of gravel typically weighs about , or one cubic yard weighs about . Gravel is an important commercial product, with a number of applications. Almost half of all gravel production is used as construction aggregate, aggregate for concrete. Much of the rest is used for road construction, either in the road base or as the road surface (with or without bitumen, asphalt or other binders.) Natu ...
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Aeolian Landform
Aeolian landforms, or Eolian landforms, are produced by either the erosion, erosive or deposition (geology), depositive aeolian processes, action of wind. These features may be built up from sand or snow, or eroded into rock, snow, or ice. Aeolian landforms are commonly observed in sandy deserts and on frozen lakes or sea ice and have been observed and studied around Earth and on other planets, including Mars and Pluto. Terminology The word "aeolian" derives from Aeolus, Æolus, the Greek god of the winds, and the son of Hellen and the nymph Orseis, and a brother of Dorus, Xuthus and Amphictyon. Mechanisms Aeolian landforms are formed when wind Sediment transport, moves sediment (see aeolian processes). Sediment particles move when they are lifted by upwards Bernoulli effect, Bernoulli forces that exceed their downwards weight or when they are dragged from their initial position. Depending on the balance of these forces, particles may either creep (roll) across the surface until ...
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Israel
Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Israeli-occupied territories, It occupies the Occupied Palestinian territories, Palestinian territories of the West Bank in the east and the Gaza Strip in the south-west. Israel also has a small coastline on the Red Sea at its southernmost point, and part of the Dead Sea lies along its eastern border. Status of Jerusalem, Its proclaimed capital is Jerusalem, while Tel Aviv is the country's Gush Dan, largest urban area and Economy of Israel, economic center. Israel is located in a region known as the Land of Israel, synonymous with the Palestine (region), Palestine region, the Holy Land, and Canaan. In antiquity, it was home to the Canaanite civilisation followed by the History of ancient Israel and Judah, kingdoms of Israel and Judah. Situate ...
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260 Boa Vista
6 (six) is the natural number following 5 and preceding 7. It is a composite number and the smallest perfect number. In mathematics A six-sided polygon is a hexagon, one of the three regular polygons capable of tiling the plane. A hexagon also has 6 edges as well as 6 internal and external angles. 6 is the second smallest composite number. It is also the first number that is the sum of its proper divisors, making it the smallest perfect number. It is also the only perfect number that doesn't have a digital root of 1. 6 is the first unitary perfect number, since it is the sum of its positive proper unitary divisors, without including itself. Only five such numbers are known to exist. 6 is the largest of the four all-Harshad numbers. 6 is the 2nd superior highly composite number, the 2nd colossally abundant number, the 3rd triangular number, the 4th highly composite number, a pronic number, a congruent number, a harmonic divisor number, and a semiprime. 6 is also the firs ...
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