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The Sahara ((アラビア語:الصحراء الكبرى), ', 'the Greatest Desert') is the largest hot desert and third largest desert after Antarctica and the Arctic.〔(【引用サイトリンク】title=Largest Desert in the World )〕 Its surface area of —including the Libyan Desert—is comparable to the respective land areas of China and the United States. The desert comprises much of the land found within North Africa, excluding the fertile coastal region situated against the Mediterranean Sea, the Atlas Mountains of the Mahgreb, and the Nile Valley of Egypt and Sudan. The Sahara stretches from the Red Sea in the east, girting the Mediterranean, to the Atlantic Ocean in the west, where the landscape gradually transitions to a coastal plain. To the south, it is delimited by the Sahel, a belt of semi-arid tropical savanna that comprises the northern region of central and western Sub-Saharan Africa. Many of its sand dunes reach over in height.〔Strahler, Arthur N. and Strahler, Alan H. (1987) ''Modern Physical Geography'' Third Edition. New York: John Wiley & Sons. ISBN 0471850640. p. 347〕 Its name is derived from the plural Arabic language word for desert ( '〔("Sahara." ) ''Online Etymology Dictionary.'' Douglas Harper, Historian. Retrieved 25 June 2007.〕 (:ˈsˤɑħɑːrɑː)). ==Overview== The Sahara is bounded by the Atlantic Ocean to the west, the Atlas Mountains and the Mediterranean to the north, the Red Sea to the east, and the Sudan and the valley of the Niger River to the south. The Sahara is divided into the regions of western Sahara, the central Ahaggar Mountains, the Tibesti Mountains, the Aïr Mountains (a region of desert mountains and high plateaus), the Ténéré desert, and the Libyan Desert (the most arid region). The highest peak in the Sahara is Emi Koussi () in the Tibesti Mountains in northern Chad. The Sahara is the largest desert on the African continent. The southern border of the Sahara is marked by a band of semiarid savanna called the Sahel, south of which lies Southern Sudan and the Congo River Basin. Most of the Sahara consists of rocky hamada; ergs (large areas covered with sand dunes) form only a minor part. People lived on the edge of the desert thousands of years ago〔(Discover Magazine ), 2006-Oct.〕 since the last ice age. The Sahara was then a much wetter place than it is today. Over 30,000 petroglyphs of river animals such as crocodiles〔(National Geographic News ), 17 June 2006.〕 survive, with half found in the Tassili n'Ajjer in southeast Algeria. Fossils of dinosaurs, including ''Afrovenator'', ''Jobaria'' and ''Ouranosaurus'', have also been found here. The modern Sahara, though, is not lush in vegetation, except in the Nile Valley, at a few oases, and in the northern highlands, where Mediterranean plants such as the olive tree are found to grow. It was long believed that the region had been this way since about 1600 BCE, after shifts in the Earth's axis increased temperatures and decreased precipitation.〔(Sahara's Abrupt Desertification Started by Changes in Earth's Orbit ), Accelerated by Atmospheric and Vegetation Feedbacks.〕 However, this theory has recently been called into dispute, when samples taken from several 7 million year old sand deposits led scientists to reconsider the timeline for desertification.〔(Aridification of the Sahara desert caused by Tethys Sea shrinkage during the Late Miocene ).〕 The people of the Sahara are of various origins. Among them the Amaziɣ including the Turūq, various Arabized Amaziɣ groups such as the Hassaniya-speaking Sahrawis, whose populations include the Znaga a tribe whose name is a remnant of the pre-historic Zenaga language. Other major groups of people include the Toubou, Nubians, Zaghawa, Kanuri, Hausa, Songhai, and Fula/Fulani ((フランス語:Peul); (フラニ語:Fulɓe)). Important cities located in the Sahara include Nouakchott, the capital of Mauritania; Tamanrasset, Ouargla, Béchar, Hassi Messaoud, Ghardaïa, and El Oued in Algeria; Timbuktu in Mali; Agadez in Niger; Ghat in Libya; and Faya-Largeau in Chad. The Sahara was originally occupied by the Amaziɣ people whose name for the region was "Tinariwen", meaning deserts, a reference to the fact that they differentiated between the different ecoregions of the desert (i.e. erg, oasis, xeric shrublands etc.) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「sahara」の詳細全文を読む スポンサード リンク
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