Rock, usually limestone, composed of oolites.

岩石岩石，通常指石灰岩，由鲕粒岩组成。

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All fibrous formations form from saturated solutions being squeezed out of pores in the bedrock (usually limestone) and depositing at they hit air.

所有纤维状沉积物都是由基岩(通常是石灰岩)的孔隙中受压的饱和溶液形成的，当他们遇到空气，就结晶沉积下来。

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Limestone is usually mined in vast open-cast quarries, many of which will also carry out some processing of the materials.

石灰石通常在大型露天采石场开采，其中，许多还将进行一些材料的处理。

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Usually this layer is a soluble carbonate rock, such as limestone or its purer form, chalk.

BBC: Who, What, Why: How are sinkholes formed?