Erg Responsibilities

The NHB ERG is structured to support the requirements and bylaws of an Employee Resource Group (ERG) (See Figure 1). This structure.

Linear Dunes, An erg (also sand sea or dune sea, or sand sheet if it lacks ) is a broad, flat area of covered with -swept with little or no vegetative cover. The term takes its name from the word ʿarq ( عرق), meaning 'dune field'.

Strictly speaking, an erg is defined as a desert area that contains more than 125 km 2 (48 sq mi) of 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, covers 9 million square kilometres (3.5 × 10 ^ 6 sq mi) and contains several ergs, such as the ( ) and the ( ) in. Approximately 85% of all the Earth's mobile sand is found in ergs that are greater than 32,000 km 2 (12,355 sq mi). Ergs are also found on other, such as, and 's moon. ( ) Ergs are concentrated in two broad belts between to and to latitudes, which include regions crossed by the dry, subsiding air of the.

Active ergs are limited to regions that receive, on average, no more than 150 mm of annual precipitation. The largest are in and, and,. In, ergs are limited by the, but they do contain extremely large dunes in coastal and northwestern. They are also found in several parts of the northeast coast of. The only active erg in is in the ( ) that extends from the in the northwestern Mexican state of to the of and the of southeastern. An erg that has been fixed by vegetation forms the ( ).

Taj mahal greatest hits. Satellite image of (Arabia's Empty Quarter), the world's largest erg with an area of more than 600,000 km 2 (230,000 sq mi) ( ) Sand seas and dune fields generally occur in regions downwind of copious sources of dry, loose sand, such as dry and, dry,. Almost all major ergs are located downwind from river beds in areas that are too dry to support extensive vegetative cover and are thus subject to long-continued wind erosion. Sand from these abundant sources migrates downwind and builds up into very large dunes where its movement is halted or slowed by barriers to windflow or by convergence of windflow. Entire ergs and dune fields tend to migrate downwind as far as hundreds 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, in North Africa, and in central Asia. Sand seas that have accumulated in subsiding structural and topographic basins, such as the ( ) of, may attain great thicknesses (more than 1000 m ) but others, such as the ergs of linear dunes in the ( ) and ( ) of Australia, may be no thicker than the individual dunes superposed on the.

Within sand seas in a given area, the dunes tend to be of a single type. For example, there are ergs or fields of linear dunes, of crescentic dunes, of star dunes, and of parabolic dunes, and these dune arrays tend to have consistent orientations and sizes.

By nature, ergs are very active. Smaller dunes form and migrate along the flanks of the larger dunes and sand ridges. Occasional fills basins formed by the dunes; as the water evaporates, deposits are left behind. Individual dunes in ergs typically have widths, lengths, or both dimensions greater than 500 m (1,600 ft). 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 1 m (3.3 ft) in the Simpson Desert, and 21–43 m (69–141 ft) in the Sahara. This is far shallower than ergs in prehistoric times were.

Evidence in the geological record indicates that some and ergs reached a mean depth of several hundred meters. Extraterrestrial ergs.

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See also: Ergs are a geological feature that can be found on where an capable of significant acts on the surface for a significant period of time, creating and allowing it to accumulate. Today at least three bodies, apart from Earth, are known in the to feature ergs on their surface: Venus, Mars and Titan. Venus At least two ergs have been recognized by the on: the Aglaonice dune field, which covers approximately 1,290 km 2 (500 sq mi), and the Meshkenet dune field (17,120 km 2 or 6,600 sq mi). These seem to be mostly transverse dune fields (with dune crests perpendicular to prevailing winds). Mars shows very large ergs, especially next to the polar caps, where dunes can reach a considerable size.

Ergs on Mars can exhibit strange shapes and patterns, due to complex interaction with the underlying surface and wind direction. Titan Radar images captured by the spacecraft as it flew by in October 2005 show sand dunes at Titan's equator much like those in deserts of Earth. Kabhi alvida songs. One erg was observed to be more than 930 miles (1,500 km) long. Dunes are a dominant landform on Titan.

Approximately 15-20% of the surface is covered by ergs with an estimated total area of 12–18 million km 2 making it the largest dune field coverage in the solar system identified to date. The sand dunes are believed to be formed by wind generated as a result of tidal forces from Saturn on Titan's atmosphere.

The images are evidence that these dunes were built from winds that blow in one direction before switching to another and then back to the first direction and so on, causing the sand dunes to build up in long parallel lines. These tidal winds combined with Titan's west-to-east zonal winds create dunes aligned west-to-east nearly everywhere except close to mountains, which alter wind direction. The sand on Titan might have formed when liquid methane rained and eroded the ice bedrock, possibly in the form of flash floods. Alternatively, the sand could also have come from organic solids produced by photochemical reactions in Titan's atmosphere. See also. – Processes due to wind activity.

– Depressions in a sand dune ecosystem caused by the removal of sediments by wind. – A desert surface covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size. – A streamlined aeolian landform References. Archived from on 2006-10-01. Retrieved 2006-05-18. Desert Guide.

Retrieved 2006-05-18. Parrish, Judith Totman (2001).

Columbia University Press. Spector, Christy (September 24, 2001). Archived from on 2006-08-28. Retrieved 2006-05-18. Cooke, Ronald U.; Warren, Andrew (1973). University of California Press.

Middleton, Nick (2009). Oxford University Press.

Desert sandflow basins and a model for the development of ergs. Geographical Journal, v. Glennie, K.W. Desert sedimentary environments: Developments in sedimentology 14, Enclosure 4. New York: American Elsevier Publishing Co. Breed, C.S., and T. Morphology and distribution of dunes in sand seas observed by remote sensing.

In A study of global sand seas, edited by E.D. Geological Survey Professional Paper 1052, pp. Breed, C.S., S.G. Fryberger, S. Andrews, C.K. Gebel, and K. Regional studies of sand seas using Landsat (ERTS) imagery.

In A study of global sand seas, edited by E.D. Geological Survey Professional Paper 1052, pp.

Pye, Kenneth; Tsoar, Haim (2009). Lunar and Planetary Science XXXVI (2005). Greeley, R., et al.

(1992), Journal of Geophysical Research, 97(E8), 13,319–13,345. Britt, Robert Roy (2003-11-10). Archived from on 2006-03-07. Stiles, Lori (2006-05-04). University of Arizona.

Bourke, Mary C.; Nick Lancaster; Lori K. Fenton; Eric J.R. Parteli; James R. Zimbelman; (2010).

'Extraterrestrial dunes: An introduction to the special issue on planetary dune systems'. Elsevier B.V. Goudarzi, Sara (2006-05-04). External links.