mother nature: Sahara - The Largest Desert in the World

Sunday, May 14, 2017

Sahara - The Largest Desert in the World

Sahara (Arabic: الصحراء الكبرى‎‎, aṣ-ṣaḥrāʾ al-kubrā , 'the Greatest Desert') is the largest hot desert, and third largest desert after Antarcticaand the Arctic. Its area of 9,400,000 square kilometres (3,600,000 sq mi) is comparable to the area of the United States. It is amounting to 31% of Africa. The desert comprises much of North Africa, excluding the fertile region on theMediterranean coast, the Atlas Mountains of the Maghreb, and the Nile Valley in Egypt andSudan. The Sahara stretches from the Red Seain the east and the Mediterranean in the north, to the Atlantic Ocean in the west, where the landscape gradually changes to a coastal plain. To the south, it is bounded by the Sahel, a belt of semi-arid tropical savannaaround the Niger River valley and the Sudan Region ofSub-Saharan Africa.

The Sahara is mainly rocky hamada. Ergs (large areas covered with sand dunes) form only a minor part, but many of the sand dunes are over 180 metres (590 ft) high.Several deeply dissected mountains, many volcanic, rise from the desert, and the Red Sea hills. Most of the rivers and streams in the Sahara are seasonal or intermittent, the chief exception being the Nile Riverwhich, from its origins in central Africa, crosses the desert underground before emptying into the Mediterranean, although aquifers sometimes surface, forming oases. These include the Bahariya, Ghardaïa, Timimoun, Kufra, and Siwa.

An oasis in the desert

People lived on the edge of the desert thousands of years ago 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 survive, with half found in the Tassili n'Ajjer in southeastAlgeria. Fossils of dinosaurs, including Afrovenator, Jobaria and Ouranosaurus, have also been found here. Source: Wikipedia