"and western Asia, and Central Australia. In South America, ergs are limited by the Andes Mountains, but they do contain extremely large dunes in coastal Peru and northwestern Argentina. They are also found in several parts of the northeast coast of Brazil. The only active erg in North America is in the Gran Desierto de Altar () that extends from the Sonoran Desert in the northwestern Mexican state of Sonora to the Yuma Desert of Arizona and the Algodones Dunes of southeastern California. An erg that has been fixed by vegetation forms the Nebraska Sandhills (). Sand seas and dune"
"of the Sahara is probably As-Sahra al-Libiyah, which straddles the inland border of Libya and Egypt. Erg is a Tamachek Berber word, and also a geographic term of art. The Grand Erg Oriental used to be associated with the Wadi Igharghar, a mostly dry and buried river with a sizable network of tributaries which, should it possess any water, would flow north into the erg from the Ahaggar mountains of the central Sahara. Yet such dry, anciently-made river beds, lying seemingly useless beneath the desert sands, can preserve the infrequent rain water, by carrying it off underground and so rescue"
"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 . Ergs are also found on other celestial bodies, such as Venus, Mars, and Saturn's moon Titan. Ergs are concentrated in two broad belts between 20° to 40°N and 20° to 40°S latitudes, which include regions crossed by the dry, subsiding air of the trade winds. Active ergs are limited to regions that receive, on average, no more than 150 mm of annual precipitation. The largest are in northern and southern Africa, central"
"Erg The erg is a unit of energy and work equal to 10 joules. It originated in the centimetre–gram–second (CGS) system of units. It has the symbol ""erg"". The erg is not an SI unit. Its name is derived from ""ergon"" (ἔργον), a Greek word meaning ""work"" or ""task"". An erg is the amount of work done by a force of one dyne exerted for a distance of one centimeter. In the CGS base units, it is equal to one gram centimeter-squared per second-squared (g·cm/s). It is thus equal to 10 joules or 100 nanojoules (nJ) in SI units. An"
"is still widely used in astrophysics and sometimes in mechanics. Erg The erg is a unit of energy and work equal to 10 joules. It originated in the centimetre–gram–second (CGS) system of units. It has the symbol ""erg"". The erg is not an SI unit. Its name is derived from ""ergon"" (ἔργον), a Greek word meaning ""work"" or ""task"". An erg is the amount of work done by a force of one dyne exerted for a distance of one centimeter. In the CGS base units, it is equal to one gram centimeter-squared per second-squared (g·cm/s). It is thus equal to"
"Erg Iguidi The Erg Iguidi (), is a large erg in the area of Tindouf in southwestern Algeria extending into northern Mali and Mauritania. The Erg Iguidi is a sandy desert with a clear pattern of narrow linear dunes stretching for a length of 400 km. Part of the greater Sahara, it is located in its northwestern region and is characterized by Harmattan withering winds. The highest point is 540 m. Compared to the neighboring Erg Chech to the south, this erg is relatively humid. Groundwater is especially abundant towards the north-eastern edge of the Erg Iguidi. There are patches"
"greater than . Both the regional extent of their sand cover and the complexity and great size of their dunes distinguish ergs from dune fields. The depth of sand in ergs varies widely around the world, ranging from only a few centimeters deep in the Selima Sand Sheet of Southern Egypt, to approximately in the Simpson Desert, and in the Sahara. This is far shallower than ergs in prehistoric times were. Evidence in the geological record indicates that some Mesozoic and Paleozoic ergs reached a mean depth of several hundred meters. Ergs are a geological feature that can be found"
"the language of the nomads, who habitually reside in such places."" For these and similar reasons concerning the desert ecology of water, the geographer and historian of the Sahara E.-F. Gautier once wrote referring to the Grand Erg Oriental as ""the great Igharghar Erg"". Accordingly, surface moisture, seasonal pastures, and wells may reflect unseen conditions beneath the sands. What appears as an entirely inhospitable erg can elsewhere, in stark contrast, offer the fruits of ""some buried wadi"". To the north of the erg, the Aurès mountains provide abundant runoff. These waters feed the artesian aquifer of the Jerid, despite its"
"to the Tuareg people, the elliptical strewn field stretches for more than . Erg Chech The Erg Chech (), is a large erg in southwestern Algeria and northern Mali. It is an almost uninhabited part of the greater Sahara Desert, an inhospitable desert region with long, extremely hot summers and short, very warm winters. The Erg Chech is a vast sandy expanse including compound and complex linear and star dunes. The mean elevation of the Erg Chech is just above 300 m, slightly lower than the neighboring Erg Iguidi stretching to the north. The barren plain of the Tanezrouft is"
"Erg Chech The Erg Chech (), is a large erg in southwestern Algeria and northern Mali. It is an almost uninhabited part of the greater Sahara Desert, an inhospitable desert region with long, extremely hot summers and short, very warm winters. The Erg Chech is a vast sandy expanse including compound and complex linear and star dunes. The mean elevation of the Erg Chech is just above 300 m, slightly lower than the neighboring Erg Iguidi stretching to the north. The barren plain of the Tanezrouft is located to the southeast. One of the localities of the commune of Akabli"
"erg) occupy about one-quarter of the territory. The largest such region is the Grand Erg Oriental (Great Eastern Erg), where enormous dunes high are spaced about apart. Much of the remainder of the desert is covered by rocky platforms called humud (sing., hamada), and almost the entire southeastern quarter is taken up by the high, complex mass of the Ahaggar and Tassili n'Ajjer highlands, some parts of which reach more than . Surrounding the Ahaggar are sandstone plateaus, cut into deep gorges by ancient rivers, and to the west a desert of pebbles stretches to the Mali frontier. The desert"
"""Grand Erg Oriental"". In addition to oil in Wargla and Hassi Messaoud (see above), other Algerian hydrocarbon sites include In Salah, a city (pop: 44,000) to the erg's southwest, yielding natural gas, and also El Adeb Larache, Edjelé, Tingentourine, and Zarzaïtine (south of the erg, close to Libya). One of Algeria's largest field of natural gas is near Ghardaïa, west of Touggourt. Gas pipelines have been constructed north to the Mediterranean port of Bourgie, and later northeast through Tunisia. Along the north rim of the ""Grand Erg Oriental"", both the physical ecology and the human culture surviving there since ancient"
"Esker An esker, eskar, eschar, or os, sometimes called an ""asar"", ""osar"", or ""serpent kame"", is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North America. Eskers are frequently several kilometres long and, because of their peculiar uniform shape, are somewhat like railway embankments. The term ""esker"" is derived from the Irish word ""eiscir"" (Old Irish: ""escir""), which means ""ridge or elevation, especially one separating two plains or depressed surfaces"". The Irish word was and is used particularly to describe long sinuous ridges, which are now"
"emission from the solidified lava is roughly the same as the surrounding natural rock, which has some naturally occurring uranium. To date, some limited follow up by French personnel has taken place, but no long-term study of the native population, nor the aquifers in the area has been done. In Eker In Eker (also written as I-n-Eker or In Ekker) is a village in the commune of In Amguel, in Tamanrasset District, Tamanrasset Province, Algeria. It lies on the N1 national highway north of In Amguel and north of Tamanrasset city. In Eker has a hot desert climate (Köppen climate"
"edge. Tuareg Berbers (a people sourced in the central Sahara) compose the majority in Ghadames. This oasis was known by ancient Egypt, and later by Carthage and by Rome, as Cydamus. A Libyan road from Tarabulus on the Mediterranean coast now leads to present-day Ghadames. The historic Saharan architecture found in its Old Town has received international recognition. In Algeria Oued Irara Airport at Hassi Messaoud (located in the erg) serves a few international flights and also national flights. Ouargla Airport (OGX) has limited international and national flights. North of the erg Guemar Airport, 20 km. from El Oued, has"
"of seasonal vegetation with grasses and shrubs and in the summer the desert is used as a pasturage area. The Erg Iguidi supports a population of slender-horned gazelle. Erg Iguidi The Erg Iguidi (), is a large erg in the area of Tindouf in southwestern Algeria extending into northern Mali and Mauritania. The Erg Iguidi is a sandy desert with a clear pattern of narrow linear dunes stretching for a length of 400 km. Part of the greater Sahara, it is located in its northwestern region and is characterized by Harmattan withering winds. The highest point is 540 m. Compared"
"finer particles have been stripped by the wind. These are called ""reg"" in the western Sahara, ""serir"" in the eastern Sahara, ""gibber plains"" in Australia and ""saï"" in central Asia. The Tassili Plateau in Algeria is an impressive jumble of eroded sandstone outcrops, canyons, blocks, pinnacles, fissures, slabs and ravines. In some places the wind has carved holes or arches, and in others, it has created mushroom-like pillars narrower at the base than the top. In the Colorado Plateau it is water that has been the eroding force. Here the Colorado River has cut its way over the millennia through"
"been stabilized by the growth of vegetation, allowing human cultivation of crops like millet and sorghum on the slopes. The ancient Bornu Empire to Fezzan caravan routes had to cross the dunes of the erg south of Bilma as the last major obstacle before reaching the sahel. While that traffic largely ceased after 1820, trade though the erg of Bilma continues from the Lake Chad region and the Termit Massif on a small scale. Erg of Bilma The Erg of Bilma is a dune sea (Arabic: ""erg"") in the Ténéré desert region of the south central Sahara Desert. The Erg"
"included, the Sahara would be . It is one of three distinct physiographic provinces of the African massive physiographic division. The Sahara is mainly rocky hamada (stone plateaus); ergs (sand seas – large areas covered with sand dunes) form only a minor part, but many of the sand dunes are over high. Wind or rare rainfall shape the desert features: sand dunes, dune fields, sand seas, stone plateaus, gravel plains (""reg""), dry valleys (""wadi""), dry lakes (""oued""), and salt flats (""shatt"" or ""chott""). Unusual landforms include the Richat Structure in Mauritania. Several deeply dissected mountains, many volcanic, rise from the"
"during the 11th and 12th centuries settlers with a Walloon origin (""latins"" in Hungarian) moved to this territory. The basin of Eger and the hilly region around it have always been very suitable for human settlements, and there are many archaeological findings from the early ages of history, which support this fact. The other names of the town are in Latin as Agria, in Serbian and Croatian as Jegar / Јегар or Jegra / Јегра, in Czech and Slovene language as Jager, in Slovak language as Jáger, in Polish as Jagier, and in Turkish as Eğri. The shield of Eger"
"separates the Ore Mountains from the Bohemian Central Mountains, where the River Ohře leaves the graben and flows into the Elbe south of the Bohemian Mountains. The Eger Graben is part of the European Cenozoic Rift System and was created geologically on the same principle as the Rhine Rift Valley. It was formed by the almost complete erosion of the Variscan Mountains and sits on a fault-block caused by the horizontal pressure of the African continental plate. This block dropped, however, in contrast to the surrounding area. The Ore Mountains are fault-block mountains which rise very gently in Germany, but"
"times are said to form a continuum. From Biskra (pop: 200,000) in Algeria by the Aurès mountains, this region extends east to the Djerid of Tunisia. It is a low-lying area of chotts (salt pans), and occasional oases, where exists intensive cultivation of date palms in the tens of thousands. Between Biskra and the Djerid, but a little to the south, lies El Oued, a mid-sized Algerian city (pop: 139,000), graced with domes and arches of Saharan architecture. Also an oasis, it's located about 100 km. east of Touggourt and by the northern frontier of the erg. The thirst of"
"Erg of Bilma The Erg of Bilma is a dune sea (Arabic: ""erg"") in the Ténéré desert region of the south central Sahara Desert. The Erg of Bilma stretches southwest from Fachi and the Tibesti Mountains. On the west it is bounded by the Aïr Mountains in north central Niger, and to the east it passes Bilma, continuing on to the Chadian border. It surrounds on three sides the oasis of Bilma, southernmost of a north–south string of oasies of the Kaouar rise. The Erg covers an area of approximately . At its southernmost edge, some of the dunes have"
"of kilometers from their sources of sand. Such accumulation requires long periods of time. At least one million years are required to build ergs with very large dunes, such as those on the Arabian Peninsula, in North Africa, and in central Asia. Sand seas that have accumulated in subsiding structural and topographic basins, such as the Murzuk Sand Sea () of Libya, may attain great thicknesses (more than 1000 m) but others, such as the ergs of linear dunes in the Simpson Desert () and Great Sandy Desert () of Australia, may be no thicker than the individual dunes superposed"
"Agger (ancient Rome) An agger is an ancient Roman embankment or rampart, or any artificial elevation. It is a Latin word. The agger was an embankment that gave Roman roads the proper draining base. Basically the agger is a ridge that supports the road surface. The agger was constructed by excavating the line of the road, building a firm foundation, refilling and compressing the soil, adding more soil from digging drainage ditches or fosses on one or both sides of the road, then surfacing with graded layers of stone and cobbles. The material used to build the aggers was dug"
"modern era – such borrowings are mainly words of a geographic or topographical nature. Another such word is crag (from Welsh ""craig"" ""rock""). Tors are landforms created by the erosion and weathering of rock; most commonly granites, but also schists, dacites, dolerites, coarse sandstones and others. Tors are mostly less than high. Many hypotheses have been proposed to explain their origin and this remains a topic of discussion among geologists and geomorphologists, and physical geographers. It is considered likely that tors were created by geomorphic processes that differed widely in type and duration according to regional and local differences in"
"word ""igherman"" might be a cognate word, with an identical meaning, with the word ""Garamantes"", which is the name of the ancient Berber city-states in modern-day Libya. Ksour in the Maghreb typically consist of attached houses, often having collective ghorfa (granaries) and other structures like a mosque, bath, oven, and shops. Ksour / ""igherman"" are widespread among the oasis populations of North Africa. Ksars are sometimes situated in mountain locations to make defense easier; they often are entirely within a single, continuous wall. The building material of the entire structure is normally adobe, or cut stone and adobe. The idea"
"Tuareg Shield The Tuareg Shield is a geological formation lying between the West African craton and the Saharan Metacraton in West Africa. Named after the Tuareg people, it has complex a geology, reflecting the collision between these cratons and later events. The landmass covers parts of Algeria, Niger and Mali. The Tuareg Shield is mainly composed of Archean or Paleoproterozoic terranes and Neoproterozoic terranes that amalgamated during the Pan African orogeny when the West African craton and the Saharan metacraton converged. The shield originated in oceanic island arcs that formed on the cratons during 900 Ma to 680 Ma, of"
"drop very steeply into the Eger Graben. The trench thus follows the main fault line of the Ore Mountains. Eger Graben The Eger Graben (, ), much less commonly called the Ohre or Ohře Graben, is a geographical unit in the Czech Republic. It runs southwards, parallel to the Ore Mountains (""Krušné Hory"") and its formation is linked with that of the mountain range. The Ohře (equally commonly known in English by its German name ""Eger"", hence the name of the trough) flows through the Eger Graben and separates the Ore Mountains from the Slavkovský les and the Doupov Mountains."
"on planets where an atmosphere capable of significant wind erosion acts on the surface for a significant period of time, creating sand and allowing it to accumulate. Today at least three bodies, apart from Earth, are known in the solar system to feature ergs on their surface: Venus, Mars and Titan. At least two ergs have been recognized by the Magellan probe on Venus: the Aglaonice dune field, which covers approximately , and the Meshkenet dune field (~). These seem to be mostly transverse dune fields (with dune crests perpendicular to prevailing winds). Mars shows very large ergs, especially next"
"grew so abundantly along the banks of the Eger Stream. This explanation seems to be correct because the name of the town reflects its ancient natural environment, and also one of its most typical plants, the elder, large areas of which could be found everywhere on the marshy banks of the Stream although they have since disappeared. The German name of the town: Erlau=Erlen-au (elder grove) also speaks in favour of this supposition. And there is another theory which says that Eger's name comes from the Latin word: ""ager"" (earth). This theory comes from more recent researchers who think that"
"Eger Graben The Eger Graben (, ), much less commonly called the Ohre or Ohře Graben, is a geographical unit in the Czech Republic. It runs southwards, parallel to the Ore Mountains (""Krušné Hory"") and its formation is linked with that of the mountain range. The Ohře (equally commonly known in English by its German name ""Eger"", hence the name of the trough) flows through the Eger Graben and separates the Ore Mountains from the Slavkovský les and the Doupov Mountains. The trench continues to the northeast along the valley of the Bílina and later, as the North Bohemian Basin,"
"Serge (fabric) Serge is a type of twill fabric that has diagonal lines or ridges on both sides, made with a two-up, two-down weave. The worsted variety is used in making military uniforms, suits, great coats and trench coats. Its counterpart, silk serge, is used for linings. French serge is a softer, finer variety. The word is also used for a high quality woolen woven fabric. The name is derived from Old French , itself from Latin , from Greek (""serikos""), meaning ""silken"". The early association of silk serge, Greece, and France is shown by the discovery in Charlemagne's tomb"