Nam Đỗ Blog

SECTION 4 
You will hear a lecturer talking about caves. 
If there is one natural feature which has long fascinated man, it is caves -- those 
natural underground spaces into which people can enter. No known cave in the world 
can exist without it being extensively explored, whether it be in remote areas, such 
as the Clearwater Cave in Borneo, or immensely long and difficult, such as 
Mammoth Cave in America, or perhaps the most challenging: those caves below the 
water table, full with water -- in which ease the exploration is known as cave diving. 
Whatever the ease, if the caves are known, as complex and difficult as they usually 
are, they will be explored. 
The formal name for the study of caves is speleology — and involves many 
disciplines, such as chemistry, geology, biology, and cartography, or the science of 
making accurate maps, since the largest caves can be hundreds of kilometers long 
and highly complicated. If the exploration is just for fun, the activity is known as 
caving, but with the difficulties and dangers involved, the average caver is 
often involved with one of these speleological sciences. 
As for the number of caves in the world, research suggests that only a fraction have 
been found and documented, mostly in the areas in which caving has long been a 
popular activity, such as in America, France, or Australia. China, for example, has 
huge areas of limestone bedrock—prime material for cave formation—and 
logically must contain among the largest number of caves in the world, 
yet only few are documented due to the lack of interest in caving there. Thus, as 
exploration continues, new caves will be discovered, and it is likely that the numbers 
could radically change in the future. 
With caves being such mysterious and intriguing places, the obvious question 
concerns how they form. The most common cause is the effect of slightly acidic 
water in a process called 'dissolution'. Here, water seeps into the ground, and down 

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