The rugged texture of the Altun Mountains (upper left) that forms part of the northern boundary of the Tibetan Plateau contrasts dramatically with the Takla Makan Desert of western China. Immediately north of the mountains there are large alluvial fans on the north facing slopes, gradually sloping downward in elevation. The elevations from the mountains to the desert floor vary from over 9000 feet (2743 meters) to slightly more than 3000 feet (914 meters) above sea level. The darker swath (diagonal, linear-looking feature) found at the base of the alluvial deposits has more moisture with sparse vegetation. Sand dunes and sand ridges are visible along the northern (lower right) margin of the image. The small dark feature (right center) appears to be a pool of water. The narrow dark swath that parallels the larger swath is a section of the southern route of the Silk Road that was once one of the major corridors linking western China with central Asia.