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One kind of rock makes this whole underground world possible limestone. Most of the world' s caves are found within it and it covers nearly 10 of the earth' s surface. Limestone is composed of minerals derived from marine shells and corals, so although this rocky escarpment in the United States is now hundreds of metres above sea level it was actually formed under water. The limestone towers of Vietnam' s Ha Long Bay are a reminder of this link with the sea. Originally, this whole area would have been one solid block of limestone, the base of a coral reef. In Borneo, rain has sculpted the limestone into extremely sharpsided pinnacles. But the dissolving power of rainwater has other, much more dramatic effects underground. |
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yǒu yī zhǒng yán shí shǐ zhè zhǒng dòng xué de xíng chéng chéng wéi kě néng, zhè jiù shì shí huī yán. shì jiè shang jué dà duō shù yán dòng dōu shì yóu shí huī yán xíng chéng de. dì qiú biǎo biān jìn 10 fù gài zhe shí huī yán. shí huī yán shì yóu hǎi yáng bèi ké lèi hé shān hú gǔ gé zhōng de kuàng wù zhì zǔ chéng de, jǐn guǎn wèi yú měi guó de zhè zuò xuán yá gāo chū hǎi píng miàn shù bǎi mǐ, dàn shí jì shang tā shì zài shuǐ xià xíng chéng de. wèi yú yuè nán xià lóng wān de zhèi xiē shí huī yán shān kě yǐ ràng wǒ men kàn dào tā yǔ hǎi yáng de lián xì. zuì chū zhè yī dì qū běn shì yí gè wán zhěng de shí huī yán bǎn kuài, yī zuò shān hú jiāo de jiāo dǐ. zài jiā lǐ màn dān dǎo, yǔ shuǐ bǎ shí huī yán diāo kè chéng le zhè zhǒng biān yuán yì cháng jiān lì de shí zhù. dàn shì, zài dì xià yǔ shuǐ de chōng shí zuò yòng yǔ cǐ bù tóng, bìng qiě gèng yǒu xì jù xìng. |