Thread: Ask a Scientist
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Old 22.03.2021, 19:01
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Re: Ask a Scientist

Here's one for the geologists.

Caves frequently form in limestone rock caused by water percolating through the rock and dissolving away minute quantities of the rock.

Over millions of years, sufficient material is removed that caves form. Sometimes huge caves. Whole networks of caves.

And then?

Well, stalagtites and stalagmites form inside the cave. These are formed by the same water that has been trickling down through the same layers above and thus that actually formed the caves in the first place. But rather than continue to remove limestone, they actually reverse the process and deposit some and form stalagmites and stalagtites. Every droplet of water adding a minute amount of material.

I guess that if you wait several more millions of years these stalagmites and stalagtites will meet in the middle to form pillars, and the pillars will grow in girth until all available space is filled and effectively the cave is gone and the original condition is restored,

So why does exactly the same process that creates the cave then end up filling it in again?

A shift in temperature maybe? Or in the acidity of the water?

Does this mean there are certain periods in the earth's history that are favourable to the formation of caves, and certain periods that are favourable to them filling back in?
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