在石膏层上方和下方的沉积物中含有许多小型海洋生物化石，这表明这里的海洋环境很开放。
Sediment above and below the gypsum layer contained tiny marine fossils, indicating open-ocean conditions.
矿场(石膏层)非常坚固，巷道墙体无需加固。
As the quarry is rather solid there is no need to strengthen the walls of the tunnels.
在石膏层上下的沉积物中包含了微小的海洋生物…
Sediment above and below the gypsum layer contained tiny marine fossils , indicating open -ocean conditions .
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