Sahara Desert

The Sahara Desert is a large hot desert in North Africa spanning 9,200,000 square kilometers and covering much of the continent. It stretches from the Red Sea in the east to the Atlantic Ocean in the west and is bounded by the Sahel to the south. The desert can be divided into several regions, including the western Sahara, the central Ahaggar Mountains, the Tibesti Mountains, and the Aïr Mountains. The Sahara has alternated between desert and savanna grassland in a 20,000-year cycle due to the precession of Earth's axis. The desert covers large parts of several countries, including Algeria, Chad, Egypt, Libya, Mali, Mauritania, Niger, Western Sahara, and Sudan, and is one of the three distinct physiographic provinces of the African massive physiographic division. The Sahara is characterized by rocky hamada, ergs, sand dunes, and dry valleys, with some sand dunes reaching heights of over 180 meters. The desert is hyperarid in the central region, with sparse vegetation, but has areas of sparse grassland and desert shrub in the northern and southern reaches.learn more on wikipedia