It was Lechuguilla's gypsum crystals 龙舌兰洞的石膏结晶群

329. As the explorers went deeper into the cave,
     随着探险家们深入洞穴
330. they came across whole galleries filled with the most unusual formations,
     他们发现了成片叹为观止的地貌
331. like these 5-metre cones, frosted with the most delicate crystals.
     例如这些5米高的石锥 上面布满了雪霜一样的松脆结晶
332. It was Lechuguilla's gypsum crystals
     龙舌兰洞的石膏结晶群
333. that made scientists question how these caverns were formed.
     使科学家们产生了 这个巨洞如何形成的疑问
334. They discovered that Lechuguilla's limestone had actually been eaten away by sulphuric acid,
     他们发现龙舌兰洞的石灰岩 实际上是被硫酸侵蚀的
335. cutting through literally miles of limestone.
     凿穿了差不多数英里的石灰岩

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 332 行