The cenotes are, in effect, gigantic fresh water wells. 沼穴于是成了巨大的淡水井
These flooded shafts are the region's only source of open fresh water. 这些水潭是整个地区 唯一的露天淡水资源
Variations in water flow and the air currents 水流和气流的变化
If the water seeps though the ceiling quickly, 若是水从洞顶滴落的速度较快
This water is loaded with dissolved limestone 这些水中含有溶解的碳酸钙
But water in caves doesn't only erode. 可是洞里的水不光只是侵蚀
the water absorbed carbon dioxide from the soil 水从土壤中吸收了二氧化碳
the water takes on a new, more erosive power. 水便有了一股新的、更强的侵蚀力
When the water reaches the more resistant bed of limestone 当水流遇到更坚硬的石灰岩床时