Sahara Desert

The largest desert in the world, the Sahara Desert, spreads across most of North Africa covering an area roughly the size of the contiguous United States. Deep in the Sahara desert's interior, restless winds hurry through a desolate landscape. Dunes and rock simmer under the sun's relentless glare. Life is concentrated around scattered oases, where plants and people flourish, despite the arid vastness that surrounds them. Within the Sahara Desert, camel caravans still travel between the oases as they have for thousands of years, transporting food, salt, and other precious goods across the sea of sand. The Sahara Desert is one of the harshest and most demanding environments on Earth. For the people who call the Sahara Desert home, daily life revolves around satisfying the most basic needs: water, food, and shelter. Decades of conflict and political upheaval in the region around the Sahara Desert have fostered a deep desire to satisfy other needs as well: peace, stability, and economic development.

Vast stretches of uninterrupted sand are only one kind of Saharan Desert landscape. A diversity of land surface features, including ancient lava flows and volcanoes can be seen in the Sahara Desert. The Sahara Desert encompasses areas of Algeria, Tunisia, Libya, Chad, and Niger.

Evidence of previous volcanic activity in the Sahara Desert can be found in northeastern Chad, in particular, in a region known as Tibesti. Reaching up out of the surrounding Sahara Desert, the dark rock of the Tibesti Plateau stands out in dark brown against the sand. Scattered throughout the region are the circular cones and calderas of several volcanoes. The dark remains of a lava flow mark the location of the Tousside volcano. North of Tibesti, in Libya, more dark-colored lava beds leave their mark on the landscape on the Sahara Desert. Variety exists in the Algerian Sahara Desert, where the Grand Erg Oriental desert is hemmed in to the south by the Tinrhert Plateau. South of the Plateau, the Sahara Desert resumes briefly, only to give way to a mountainous region traced with impermanent rivers. In northern Niger, a sinuous gray-green line marks the edge of an escarpment that separates the Mangueni Plateau to the north from the rock deserts to the south. The Sahara desert can be a beautiful but often treacherous place.

Source: http://visibleearth.nasa.gov/view_rec.php?id=2253