Cutting Off the Moisture
The collision of continents ultimately isolated the portion of central Asia that includes the Gobi Desert from the moisture-laden winds from the ocean. The winds blowing up against this barrier of mountains rose until the moisture it contained condensed into rain or froze into snow. The Gobi sits surrounded by such a ring of mountains, including the Tibetan plateau to the southwest, the Altai Mountains and grassland steppes of Mongolia on the north, and the vast north China plain to the southwest. Gobi means “desert” in Mongolian, but is also known in Chinese as the shamo (sand desert) and han-hal (dry sea). It encompasses several adjacent dry basins, although some geographers divide them into separate deserts.
A high desert far from the moderating influence of the oceans, the Gobi's climate is one of great extremes, including rapid changes in temperature and furious windstorms. This high, arid region is divided into different areas: the Ka-Shun, Dzungarian, and Trans-Altai Gobi in the west, the Mongolian Gobi in the middle and east, and finally the Ala Shan Desert in the south.
Most of those regions are nearly barren. The Ka-Shun rises to some 5,000 feet (1,700 m), with long, corrugations of 300-foot-tall (91.44 m) hills, hollows, and jagged crests. The region gets only a few inches of rain a year and supports few plants, animals, streams, or springs. In lowlying depressions, water intermittently collects to support salt marshes, where only plants adapted to high concentrations of salts and other minerals in the soil can survive. The Trans Altai Gobi is a high, rugged plain bounded by mountain ranges, separated by ravines and extensive salt marshes, where the four inches (100 mm) of rain annually support only scattered plants and animals. The Ka-Shun Gobi, lying between the China-Mongolia border and the Yellow River, is a vast plain covered with sand.