景点的描述:
(1)什么是喀斯特?What is karst?
喀斯特即岩溶,是水对可溶性岩石进行以化学溶蚀作用为主,流水冲蚀、潜蚀和崩塌等机械作用为辅的地质作用,以及由这些作用所产生的现象的总称。由喀斯特作用所造成的地貌,称喀斯特地貌(岩溶地貌)。
Karstification, is mainly the chemical corrosion of water to soluble rocks, together with other geological processes, such as water erosion, suffosionand collapse. It is also a collective name for all phenomena arising from those processes. The landforms resulting from karstification is called karst landform.
(2)喀斯特地貌的形成条件 Forming conditions of karst landform
(一)岩石具有可溶性Soluble rocks
可溶性岩石是喀斯特地貌发育的物质基础,主要为灰岩、白云岩及泥灰岩等。
Soluble rocks are the material base of karst landform development, mainly includes limestone, dolomite and marl, etc.
(二)岩石具有裂隙 Rocks with fractures
孔隙和裂隙是流动水下渗的主要渠道。岩石裂隙越大,岩石的透水性越强,溶蚀作用越显著,喀斯特地貌发育越完整,并且形成一个不断扩大的循环网。
Flowing water mainly permeates along pores and fractures.
Karstification is related to fractures, larger fractures cause more obvious karstification because of the better water permeability, which will lead to better developed karst landform. And this circle process can be continuously extended.
(三)水具有溶蚀能力 Water with dissolution capacity
水的溶蚀能力来源于二氧化碳(CO2)与水结合形成的碳酸(H2CO3),二氧化碳是喀斯特地貌形成的功臣。
The dissolution capacity of water comes from carbonic acid (H2CO3), which is the combination of carbon dioxide (CO2) and water. Carbon dioxide is the key element related to karst landform.
下面几个化学方程式反映了岩溶作用的进行:
The following chemical equations record the process of karstification:
①H2O + CO2=H2CO3; ( formation of carbonic acid)
②H2CO3=H+ + HCO3-;(The dissociation of carbonic acid, to produce H+)
③H++CaCO3=HCO3-+Ca2+;(H+ reacts with CaCO3 to produce HCO3-,so that CaCO3 can be dissolved)
(四)水具有流动性 Water with mobility
流动的水溶蚀性更强烈,因为水中的二氧化碳需要得到及时的补充,水的溶蚀作用才能顺利进行,水的溶蚀能力才得以巩固加强。同时,流动的水带动河底砂砾对岩石进行机械侵蚀,更有利于岩溶作用的深入。
Flowing water has better solubility, in that the carbon dioxide in flowing water can be supplied timely and only with enough carbon dioxide, dissolution can proceed smoothly. In this case the dissolution capacity of water can be strengthened. Meanwhile, the flowing water can drive the sand and gravels at the bottom of the river to erode the rock mechanically, which will contribute to intensive karstification.