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
The Shandong Hills
These hills are basically composed of extremely ancient crystalline shales and granites of early Precambrian age (i.e., older than about 2.5 billion years) and of somewhat younger sedimentary rocks dating to about 540–420 million years ago. Faults have played a major role in creating the present relief, and, as a result, many hills are horsts (blocks of the Earth’s crust uplifted along faults), while the valleys have been formed by grabens (blocks of the Earth’s crust that have been thrust down along faults). The Jiaolai Plain divides this region into two parts. The eastern part is lower, lying at elevations averaging below 1,500 feet (450 metres), with only certain peaks and ridges rising to 2,500 feet and (rarely) to 3,000 feet (900 metres); the highest point, Mount Lao, reaches 3,714 feet (1,132 metres). The western part is slightly higher, rising to 5,000 feet (1,524 metres) at Mount Tai, one of China’s most sacred mountains. The Shandong Hills meet the sea along a rocky and indented shoreline.
The Qin Mountains
The Qin (conventional Tsinling) Mountains in Shaanxi province are the greatest chain of mountains east of the Plateau of Tibet. The mountain chain consists of a high and rugged barrier extending from Gansu to Henan; geographers use a line between the chain and the Huai River to divide China proper into two parts—North and South. The elevation of the mountains varies from 3,000 to 10,000 feet (900 to 3,000 metres). The western part is higher, with the highest peak, Mount Taibai, rising to 12,359 feet (3,767 metres). The Qin Mountains consist of a series of parallel ridges, all running roughly west-east, separated by a maze of ramifying valleys whose canyon walls often rise sheer to a height of 1,000 feet (300 metres) above the valley streams.
The Sichuan Basin
This is one of the most attractive geographical regions of China. The Sichuan Basin is surrounded by mountains, which are higher in the west and north. Protected against the penetration of cold northern winds, the basin is much warmer in the winter than are the more southerly plains of southeast China. Except for the Chengdu Plain, the region is hilly. The relief of the basin’s eastern half consists of numerous folds, forming a series of ridges and valleys that trend northeast to southwest. The lack of arable land has obliged farmers to cultivate the slopes of the hills, on which they have built terraces that frequently cover the slopes from top to bottom. The terracing has slowed down the process of erosion and has made it possible to cultivate additional areas by using the steeper slopes—some of which have grades up to 45° or more.
The southeastern mountains
Southeastern China is bordered by a rocky shoreline backed by picturesque mountains. In general, there is a distinct structural and topographic trend from northeast to southwest. The higher peaks may reach elevations of some 5,000 to 6,500 feet (1,500 to 2,000 metres). The rivers are short and fast-flowing and have cut steep-sided valleys. The chief areas of settlement are on narrow strips of coastal plain where rice is produced. Along the coast there are numerous islands, where the fishing industry is well developed.
Plains of the middle and lower Yangtze
East of Yichang, in Hubei province, a series of plains of uneven width are found along the Yangtze River (Chang Jiang). The plains are particularly wide in the delta area and in places where the Yangtze receives its major tributaries—including large areas of lowlands around Dongting, Poyang, Tai, and Hongze lakes, which are all hydrologically linked with the Yangtze. The region is an alluvial plain, the accumulation of sediment laid down by the rivers throughout long ages. There are a few isolated hills, but in general the land is level, lying mostly below 160 feet (50 metres). Rivers, canals, and lakes form a dense network of waterways. The surface of the plain has been converted into a system of flat terraces, which descend in steps along the slopes of the valleys.
The Nan Mountains
The Nan Mountains (Nan Ling) are composed of many ranges of mountains running from northeast to southwest. These ranges form the watershed between the Yangtze to the north and the Pearl (Zhu) River to the south. The main peaks along the watershed are above 5,000 feet, and some are more than 6,500 feet. But a large part of the land to the south of the Nan Mountains is also hilly; flatland does not exceed 10 percent of the total area. The Pearl River Delta is the only extensive plain in this region and is also the richest part of South China. The coastline is rugged and irregular, and there are many promontories and protected bays, including those of Hong Kong and Macau. The principal river is the Xi River, which rises in the highlands of eastern Yunnan and southern Guizhou.
The southwest
The Yunnan-Guizhou Plateau
This region comprises the northern part of Yunnan and the western part of Guizhou; its edge is highly dissected. Yunnan is more distinctly a plateau and contains larger areas of rolling uplands than Guizhou, but both parts are distinguished by canyonlike valleys and precipitous mountains. The highest elevations lie in the west, where Mount Diancang (also called Cang Shan) rises to 13,524 feet (4,122 metres). In the valleys of the major rivers, elevations drop to about 1,300 to 1,600 feet (400 to 490 metres). Particularly sharp differences in elevation and the greatest ruggedness of relief occur in the western part of the region, in the gorges of the large rivers. In the eastern part, karst processes (creating sinks, ravines, and underground streams in the limestone landscape) have developed very strongly. Scattered throughout the highlands are small lake basins, separated by mountains.
The Plateau of Tibet
This great upland massif occupies about one-fourth of the country’s area. A large part of the plateau lies at elevations above 13,000 to 16,500 feet (4,000 to 5,000 metres). The border ranges of the plateau (the Kunlun Mountains and the Himalayas) are even higher, with individual peaks rising to heights of 23,000 to 26,000 feet (7,000 to 8,000 metres) and higher. As a rule, the interior (i.e., Tibet-side) slopes of these border mountains are gentle, while the exterior slopes are precipitous. The plateau’s eastern and southern periphery is the source of many of the world’s great rivers, including the Yangtze, Huang He, Mekong, Salween, Indus, and Brahmaputra. Only in the low valleys, chiefly along the Brahmaputra valley, are there centres of human settlement.