China

The Loess Plateau

This vast plateau of some 154,000 square miles (400,000 square km) forms a unique region of loess-clad hills and barren mountains between the North China Plain and the deserts of the west. In the north the Great Wall of China forms the boundary, while the southern limit is the Qin Mountains in Shaanxi province. The average surface elevation is roughly 4,000 feet (1,200 metres), but individual ranges of bedrock are higher, reaching 9,825 feet (2,995 metres) in the Liupan Mountains. Most of the plateau is covered with loess to thicknesses of 165 to 260 feet (50 to 80 metres). In northern Shaanxi and eastern Gansu provinces, the loess may reach much greater thicknesses. The loess is particularly susceptible to erosion by water, and ravines and gorges crisscross the plateau. It has been estimated that ravines cover approximately half the entire region, with erosion reaching depths of 300 to 650 feet (90 to 200 metres).

The Yan River at Yan'an, Shaanxi province, China, in the eastern portion of the Loess Plateau.A.Topping—Rapho/Photo Researchers