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 word ʿirq (عرق), meaning 'dune field'. Strictly speaking, an erg is defined as a desert area that contains more than 125 km (48 sq mi) of 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 9 million square kilometres (3.5×10 sq mi) 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 32,000 km (12,355 sq mi), 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.
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👉 Erg (landform) in the context of Sand dunes
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 sandstone bedrock disintegrates to produce an ample supply of loose sand. Subaqueous dunes can form from the action of water flow (fluvial processes) on sand or gravel beds of rivers, estuaries, and the sea-bed.
Erg (landform) in the context of Western Desert (Egypt)
In Egypt, the Western Desert is an area of the Sahara that lies west of the river Nile, up to the Libyan border, and south from the Mediterranean Sea to the border with Sudan. It is named in contrast to the Eastern Desert which extends east from the Nile to the Red Sea, although both are part of the broader Libyan desert in North Africa. The Western Desert is mostly rocky desert, save for an area of sandy desert, known as the Great Sand Sea, lying to the west and extending across the Libyan border.The desert covers an area of 680,650 km (262,800 sq mi) which is two-thirds of the land area of the country. Its highest elevation is 1,000 m (3,300 ft) in the Gilf Kebir plateau to the far south-west of the country, on the Egypt-Sudan-Libya border.The Western Desert is barren and uninhabited save for a chain of oases which extend in an arc from Siwa, in the north-west, to Kharga in the south.It has been the scene of conflict in modern times, particularly during the Second World War.
Administratively the Western Desert is divided between various governorates; in the north and west, the Matrouh Governorate administers the area from the Mediterranean south to approx 27°40' N latitude, and the New Valley Governorate from there to the Sudan border, while in the east parts of the Western Desert lie in the Giza, Fayyum, Beni Suef, and Minya Governorates.
Erg (landform) in the context of Great Sand Sea
The Great Sand Sea is an approximately 72,000 km (28,000 sq mi) sand desert (erg) in the Sahara that stretches from western Egypt to eastern Libya, in North Africa. Most of the area is covered by sand dunes.
Erg (landform) in the context of Idehan Ubari
The Ubari Desert, Idehan Ubari, Idehan Awbari (Idehan means fine sand in Tamasheq) or Ubari Erg is an erg in the hyper-arid Fezzan region of southwestern Libya with a surface area of approximately 58,000 km. The area of the Ubari desert has been traditionally inhabited by Tuareg people, a Berber ethnic and traditionally nomadic pastoralist group.
Erg (landform) in the context of Nafud desert
The Nafud desert or simply The Nafud (Arabic: صحراء النفود, romanized: ṣahrā' an-nafūd) is a desert in the northern part of the Arabian Peninsula at 28°18′N 41°00′E / 28.30°N 41.00°E, occupying a great oval depression. It is 290 kilometres (180 mi) long and 225 kilometres (140 mi) wide, with an area of 65,000 square kilometres (25,000 sq mi).
The Nafud is an erg, a desert region located in north-central Saudi Arabia. It is noted for its sudden violent winds, which account for the large crescent-shaped dunes. The sand in the Nafud is a brick-reddish color. Rain comes once or twice per year. In some lowland areas, namely those near the Hejaz Mountains, there are oases where dates, vegetables, barley, and fruits are grown. The Nafud is connected to the Rub' al Khali by the Dahna, a corridor of gravel plains and sand dunes, 800 mi (1,287 km) long and 15 to 50 miles (24.1 to 80.5 km) wide.