英语听力：Wild China 美丽中国 -5（在线收听） |
The cave river’s course is channeled by the beds of limestone. A weakness in the rock can allow the river to increase its gradient to flow in, providing a real challenge for the cave explorers. The downward rushes halted when the water table is reached. Here the slow-flowing river carves tunnels with a more rounded profile. This tranquil world is home to specialized cave fishes, like the eyeless Golden Barb. China may have more unique kinds of cave-evolved fishes than anywhere else on earth. Above the water table, ancient caverns abandoned by the rivers slowly fill up with stalactites and stalagmites. Stalactites form as trickling water deposits its tiny quantities of rock over hundreds or thousands of years. Stalagmites grow up where lime laid and drips hit the cave floor. So far, only a fraction of China’s caves have been thoroughly prospected. And cavers are constantly discovering new subterranean marvels, many of which are subsequently developed into commercial show caves.
Finally, escaping the darkness, the cave river and its human explorers emerge in a valley far from where their journey began. For now the adventure is over. Rivers which issue from caves are the key to survival in the karst country. This vertical gorge in Guizhou Province is a focal point for the region’s wildlife.
This is one of the world’s rarest primates, Francois langur. In China, they survive in just two southern provinces, Guizhou and Guangxi, always in ragged limestone terrains. Like most monkeys, they are social creatures, and spend a great deal of time grooming each other.
Langurs are essentially vegetarian with a diet of buds, fruits and tender young leaves. Babies are born with ginger fur, which gradually turns black from the tail end.
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| 原文地址：http://www.tingroom.com/lesson/wenhuabolan/2008/340503.html |