Sahara Desert

Sahara Desert, largest desert in the world, covering about 3,500,000 sq mi (9,065,000 sq km) of North Africa from the Atlantic Ocean to the Red Sea, about 3,000 mi (4,830 km) by 1,200 mi (1,930) north to south. The terrain includes sand hills, rocky wastes, tracts of gravel, and fertile oasis. The central plateau, about 1,000 ft (305 m) above sea level, has mountain groups (Ahagger, Aïr, and Tibesti), some of which rise well over 6,000 ft (1,829 m). Rainfall averages from less than 5 in (12.7 cm) to 10 in (25 cm) annually (dry periods may last for several years), and temperatures may soar higher than 135°F (57°C) and plunge below freezing at night. Natural resources include oil, iron ore, natural gas, and phosphates. Also underground are vast aquifers holding water thought to date from the Pleistocene epoch.