the base of a coral reef. 珊瑚礁的基座

48. The limestone towers of Vietnam's Ha Long Bay
    越南下龙湾的石林
49. are a reminder of this link with the sea.
    能说明石灰岩与海洋的关系
50. Originally, this whole area would have been one solid block of limestone,
    起初 这整个地方都是 一整块坚固的石灰岩床
51. the base of a coral reef.
    珊瑚礁的基座
52. In Borneo, rain has sculptured the limestone into extremely sharp-sided pinnacles.
    在婆罗洲 雨水已将石灰岩 雕凿成无比尖削的石塔
53. But the dissolving power of rainwater has other, much more dramatic effects underground.
    不过在地下 雨水的溶解作用 还能产生其它更壮观的效果
54. Rivers that flow over limestone often seem to completely disappear.
    流经石灰岩的河川 到最后似乎总是无影无踪

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 51 行