Atlas Mountains

Atlas Mountains
Range
Jbel Toubkal in Toubkal National Park in the High Atlas
Countries	Morocco, Algeria, Tunisia
Highest point	Jbel Toubkal
- elevation	4,167 m (13,671 ft)
- coordinates	31°03′43″N 07°54′58″W / 31.06194°N 7.91611°W / 31.06194; -7.91611
Period	Precambrian
Location of the Atlas Mountains (colored red) across North Africa

The Atlas Mountains (Arabic: جبال الأطلس‎) are a mountain range across a northern stretch of Africa extending about 2,500 km (1,500 miles) through Morocco, Algeria, and Tunisia. The highest peak is Jbel Toubkal, with an elevation of 4,167 metres (13,671 ft) in southwestern Morocco. The Atlas ranges separate the Mediterranean and Atlantic coastlines from the Sahara Desert. The population of the Atlas Mountains are mainly Berbers. The terms for 'mountain' in some Berber languages are adrar and adras, believed to be cognate with the toponym.

The mountains are divided into additional and separate ranges, including the Middle Atlas, High Atlas, and Anti-Atlas. The lower Tell Atlas running near the coast and the larger Saharan Atlas running further south terminate in the Aurès Mountains located in Algeria and Tunisia. The Atlas Mountains constitute one of the distinct physiographic provinces of the larger African Alpine System division.

The mountains are or were home to a number of plant and animal species unique in Africa (often more like those of Europe) many of them are endangered and some have already gone extinct. Examples include the Atlas Cedar, the Atlas Bear (Africa's only species of bear, which is now extinct), the Barbary Leopard, the Barbary Macaque, the Atlas mountain viper, the Barbary stag, Barbary Sheep, the Barbary Lion (extinct in the wild), the North African Elephant (extinct), the African Aurochs (extinct), the Northern Bald Ibis, the European Black Pine, the Dippers, the Algerian Oak, and Cuvier's Gazelle.

Geology

Map showing the location of the Atlas Mountains across North Africa

The basement rock of most of Africa was formed in the Precambrian (approximately 4.5 billion years ago) and is much older than the Atlas mountains lying in Africa. The Atlas formed during three subsequent phases of Earth's history.

The first tectonic deformation phase involves only the Anti-Atlas, which was formed in the Paleozoic Era (~300 million years ago) as the result of continental collisions. North America, Europe and Africa were connected millions of years ago.

The tectonic boundary.

The Anti-Atlas mountains are believed to have originally been formed as part of Alleghenian orogeny. These mountains were formed when Africa and America collided, and were once a chain rivaling today's Himalayas. Today, the remains of this chain can be seen in the Fall line in the eastern United States. Some remnants can also be found in the later formed Appalachians in North America.

A second phase took place during the Mesozoic Era (before ~65 My) and consisted of a widespread extension of the Earth's crust that rifted and separated the continents mentioned above. This extension was responsible for the formation of many thick intracontinental sedimentary basins including the present Atlas. Most of the rocks forming the surface of the present High Atlas were deposited under the ocean at that time.

Finally, in the Tertiary Era (~65 million to ~1.8 million years ago), the mountain chains that today comprise the Atlas were uplifted as the land masses of Europe and Africa collided at the southern end of the Iberian peninsula. Such convergent tectonic boundaries occur where two plates slide towards each other forming a subduction zone (if one plate moves underneath the other) and/or a continental collision (when the two plates contain continental crust). In the case of the Africa-Europe collision, it is clear that tectonic convergence is partially responsible for the formation of the High Atlas, as well as for the closure of the Strait of Gibraltar and the formation of the Alps and the Pyrenees. However, there is a lack of evidence for the nature of the subduction in the Atlas region, or for the thickening of the Earth's crust generally associated with continental collisions. In fact, one of the most striking features of the Atlas to geologists is the relative small amount of crustal thickening and tectonic shortening despite the important altitude of the mountain range. Recent studies suggest that deep processes rooted in the Earth's mantle may have contributed to the uplift of the High and Middle Atlas.^[1][2]

Natural resources

The Atlas are rich in natural resources. There are deposits of iron ore, lead ore, copper, silver, mercury, rock salt, phosphate, marble, anthracite coal, and natural gas among other resources

Subranges of the Atlas Mountains

High Atlas.

The range can be divided into three general regions from west to east:

• Middle Atlas, High Atlas, and Anti-Atlas (Morocco).
• Saharan Atlas (Algeria).
• Tell Atlas (Algeria, Tunisia).

Middle Atlas range

The Middle Atlas is a portion of the Atlas mountain range lying completely in Morocco. The Middle Atlas is the westernmost of three Atlas Mountains chains that define a large, plateaued basin extending eastward into Algeria. South of the Middle Atlas and separated by the Moulouya and Oum Er-Rbia rivers, the High Atlas stretches for 700 kilometres (430 mi) with a succession of peaks among which ten reach above 4,000 metres (13,000 ft). North of the Middle Atlas and separated by the Sebou River, the Rif mountains are an extension of the Baetic Cordillera (Baetic mountains, which include the Sierra Nevada) in the south of Spain.

High Atlas

The High Atlas in central Morocco rises in the west at the Atlantic coast and stretches in an eastern direction to the Moroccan-Algerian border. At the Atlantic and to the southwest the range drops abruptly and makes an impressive transition to the coast and the Anti-Atlas range. To the north, in the direction of Marrakech, the range descends less abruptly.

On the heights of Ouarzazate the massif is cut through by the Draa valley which opens southward. In this chaos of rocks the contrasts are astonishing: water runs in some places, forming clear basins. It is mainly inhabited by Berber people, who live in small villages and cultivate the high plains of Ourika Valley.

Panoramic picture of the artificial lake of Lalla Takerkoust near Barrage Cavagnac, with the hydroelectric dam (extreme right)

Near Barrage Cavagnac, there is a hydroelectric dam that has created the artificial lake Lalla Takerkoust. The lake serves also as a source for fish for the local fishermen.

The largest villages and towns of the area are Tahanaoute, Amizmiz, Asni, Tin Mal, Ijoukak, and Oukaïmden.

Anti-Atlas ranges

The Anti-Atlas extends from the Atlantic Ocean in the southwest of Morocco toward the northeast to the heights of Ouarzazate and further east to the city of Tafilalt (altogether a distance of approximately 500 kilometres/310 miles). In the south it borders the Sahara. The easternmost point of the anti-Atlas is the Djebel Sarhro mountains and its eastern boundary is set by sections of the High Atlas range.

Saharan Atlas range

The Saharan Atlas of Algeria is the eastern portion of the Atlas mountain range. Not as high as the Grand Atlas they are far more imposing than the Tell Atlas range that runs to the north of them and closer to the coast. The tallest peak in the range is the 2,236 m (7,340 ft) high Djebel Aissa. They mark the northern edge of the Sahara Desert. The mountains see some rainfall and are better suited to agriculture than the plateau region to the north. Today most of the population of the region are Berbers.

Tell Atlas range

Panoramic view of typical Berber village (Morocco - High Atlas Mountains).

The Tell Atlas is a mountain chain over 1,500 kilometres (930 mi) in length, belonging to the Atlas mountain ranges and stretching from Morocco, through Algeria to Tunisia. It parallels the Mediterranean coast. Together with the Saharan Atlas to the south it forms the northernmost of two more or less parallel ranges which gradually approach one another towards the east, merging in Eastern Algeria. At the western ends at the Middle Atlas range in Morocco. The area immediately to the south of this range is high plateau, with lakes in the wet season and salt flats in the dry.

Aurès mountain range

The Aurès Mountains of Algeria and Tunisia are the furthest eastern portion of the Atlas mountain range.

See also

• Capsian culture
• North Africa

References and notes

1. ^ http://einstein.uab.es/c_geotectonica/WebAtlas/AtlasLitho.htm Potential field modelling of the Atlas lithosphere
2. ^ http://einstein.uab.es/c_geotectonica/WebAtlas/MaterialAtlas/Ayarzaetal2005.pdf Crustal structure under the central High Atlas Mountains (Morocco) from geological and gravity data, P. Ayarza, et al., 2005, Tectonophysics, 400, 67-84

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