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Author： Source： Updated：2019-06-24
Zonality of karst in China: karst landform in eastern China is latitudinally distributed, including tropical karst, subtropical karst and temperate karst from south to north. Because of water restriction or topography, western China has arid karst (northwestern region) and frozen plateau karst (Qinghai-Tibet Plateau).
1. Tropical karst, represented by peak forest-depression, is distributed in Guangxi, western Guangdong, eastern Yunnan, and southern Guizhou, etc. There are many underground caves, mainly dissolved arched caves. Underground rivers here have many tributaries and cover a large area, thus called the groundwater system. The average flow area is 160 square kilometers, and the largest Disu Underground River covers 1000 square kilometers. There are many depressions on the surface and average 2.5 peak cluster areas per square kilometer; the distance between depressions is 100 to 300 meters and positive landform is divided into parts, showing peak forest-depression landform. The slope of peak forest is very steep, usually higher than 45 degrees. Peak forest can also be divided into solitary peaks, sparse peaks and peak clusters with odd peaks as a typical feature of tropical karst.
The coral reefs in Chinese tropical oceans are the youngest carbonate rocks that were mostly formed in the Late Pleistocene and Holocene periods. They are only a few meters to over 10 meters above sea level, having developed large caves, natural bridges, coastal cliffs, grikes, clints, etc. to form the coral reef scenery on the island.
2. Subtropical karst landform, represented by hill-depression, is distributed south of Qinling Mountain-Huaihe River. Underground rivers are more and shorter than those in tropical karst, and the average flow area is less than 60 square kilometers. Depressions are few - only about one per square kilometer - and they decrease from south to north; on the contrary, the proportion of dry valleys increases rapidly. Positive landform is not very typical, and there are mainly the bun-shaped hills with the slope of about 25 degrees generally. The number of caves is much smaller than that in tropical karst, most caves are grike caves, and there are more arch-shaped caves in the south of subtropical karst.
3. Temperate karst is represented by karstified mountains and dry valleys; although underground caves develop, they are generally small grike caves. Karst springs are prominent, generally having large catchment area and flow, such as Baotu Spring and Niangziguan Spring, etc. There are very few depressions but many dry valleys in this area. Positive landform is similar to that of ordinary mountainous terrains, however, there are remnant hill-depression and hill-dry valley landforms on the top of the mountain developed in the ancient subtropical zone. Undercutting rivers form valleys: quasi-peak forest landform exists in some local areas, such as the banks of Juma River.
4. Karst in arid area develops weakly with only slight corrosion marks in a few limestone fissures, some of which are filled by calcite. There are very few underground caves, which cannot constitute the factors of leakage and foundation instability.
5. Karst in cold plateau Karst of Qinghai-Tibet Plateau is under the action of periglacial action with strong freeze-thaw weathering and distinctive karst landforms including common freeze-thawed rock mounds and stone walls, etc.; and the lower part covers the debris slope formed by periglacial action. There are shallow caves developed on the hillside, and some visible piercings. Occasionally there are some