Atlas Mountains
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The Atlas Mountains (Arabic: جبال الأطلس ) are a mountain range in northwest Africa extending about 2,400 km (1,500 miles) through Morocco, Algeria, and Tunisia, including The Rock of Gibraltar. The highest peak is Jbel Toubkal, with an elevation of 4,167 m (13,665 feet) located at in southwestern Morocco. The second highest mountain is the M'Goun of 4071 meters. The Atlas ranges separate the Mediterranean and Atlantic coastlines from the Sahara Desert. The population of the Atlas Mountains are mainly Berber tribes in Morocco and kabyles in Algeria.
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. To the north in Morocco lies the Rif Mountains range.
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[edit] Geology
[edit] African geology
The basement rock of most of Africa was formed in the Precambrian Era (approximately 4.5 billion to approximately 550 million years ago) and is much older than the Atlas mountains lying in Africa. The Atlas range developed later.
[edit] Creation of the Atlas Range
To understand the Atlas range, as it appears today, one must understand the parts, since its emergence took place to three different phases of Earth’s history.
The first 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 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 millions 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 thickenning 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 thickenning and tectonic shortening despite the important altitude of the mountain range.[1][citation needed] Recent studies suggest that deep processes rooted in the Earth's mantle may have contributed to the uplift of the High and Middle Atlas.[2]
[edit] Seismic activity
Because the Atlas mountains lie on the fault zone, the area is seismically active. The city of Blida in Algeria which lies today in the middle of the Tell Atlas with a population of about 265,000 (2005) inhabitants was completely destroyed by strong quakes in the 19th century. Likewise the city of Cheliff lying in Algeria with a population of ~235,000 (2005) inhabitants suffered 5,000 fatalities in a 1980 earthquake of magnitude 7.3 on Richter Scale.
[edit] 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.
[edit] Subranges of the Atlas Mountains
The range can be divided into three general regions from west to east:
- Moroccan Atlas in Morocco, which further divides from north to south into Rif, Middle Atlas, High Atlas, and Anti-Atlas.
- Saharan Atlas (Algeria).
- Tell Atlas (Algeria, Tunisia)
[edit] Moroccan Atlas ranges
From north to south the Moroccan ranges divide into the Rif range[1], the Middle Atlas range, the High Atlas range, and the Anti-Atlas range.
[edit] Rif range
The Rif is a mountainous region of northern Morocco, from Cape Spartel and Tangier in the west to Cape Tres Forcas (Ras Tleta Madari) and Oujda in the east, and from the Mediterranean Sea in the north to the river of Ouargha in the south. The people of the Rif are Berbers (Amazigh people) of north Morocco who call themselves Imazighen.
[edit] Middle Atlas range
- Main article:Middle Atlas
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 km with a succession of peaks among which ten reach above 4,000 meters. 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.
[edit] High Atlas
- Main articles: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.
Near Barrage Cavagnac, there is a hydroelectric dam that has created the artificial lake Lala 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.
[edit] Anti-Atlas ranges
- Main article:Anti-Atlas
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 km). 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.
[edit] Saharan Atlas range
- Main article: Saharan Atlas
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 2236 m 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.
[edit] Tell Atlas range
- Main article: Tell Atlas
The Tell Atlas is a mountain chain over 1,500 kilometers 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 end, it ends at the Rif and Middle Atlas ranges 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.
[edit] Aurès mountain range
- Main article: Aurès Mountains
The Aurès Mountains of Algeria and Tunisia are the furthest eastern portion of the Atlas mountain range.
[edit] See also
[edit] References and notes
- ^ The Rif is not strictly of the Atlas range, but is included here for completeness.
[edit] External links
