How does limestone rot/corrode?

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How does limestone rot/corrode?

Postby submassabielle » Oct 24, 2012 4:49 pm

Can anyone explain to me how limestone "rots," resulting in it having the strength and weight of Styrofoam?
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Re: How does limestone rot/corrode?

Postby nathanroser » Oct 24, 2012 5:44 pm

Ah saprolite, a bolt climbers best friend :grin:

Basically it's chemically weathered rock where stuff has been leached out of it. Don't know it it happens after a cave forms in the rock or it it's a feature that formed when the limestone was deposited. You can find a lot of the stuff in soil the closer to the tropics you get.
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Re: How does limestone rot/corrode?

Postby struebe » Oct 24, 2012 10:06 pm

Someone once told me (and unfortunately I don't remember the details or who told me) that bacteria/microbes can munch on components of the calcium carbonate in limestone and basically destroys its structure. I haven't done fact-checking on this, but it seemed plausible enough I figured I'd share...
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Re: How does limestone rot/corrode?

Postby submassabielle » Oct 29, 2012 9:26 am

Is it the same thing as what Art Palmer calls a "weathering rind" in chapter 12 of his "Cave Geology?" Or does that only refer to a layer of weathered powder rather than actual chunks of weathered limestone? I didn't see "saprolite" listed in the index of Palmer's book. Most of the info I found in a few cursory searches for saprolite on the internet deal with other rock types than limestone and appear to be unrelated to caves. The caves where I have been seeing this are nowhere near the tropics.
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Re: How does limestone rot/corrode?

Postby Martin Sluka » Oct 29, 2012 10:50 am

submassabielle wrote:Can anyone explain to me how limestone "rots," resulting in it having the strength and weight of Styrofoam?


Thermal water corrosion.
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Re: How does limestone rot/corrode?

Postby submassabielle » Oct 29, 2012 12:26 pm

While I am still not sure if it qualifies as a "weathering rind," after a little more research I am thinking that the limestone I have seen has been altered by sulfuric acid.
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Re: How does limestone rot/corrode?

Postby Martin Sluka » Oct 29, 2012 12:29 pm

submassabielle wrote:While I am still not sure if it qualifies as a "weathering rind," after a little more research I am thinking that the limestone I have seen has been altered by sulfuric acid.


Exactly.
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Re: How does limestone rot/corrode?

Postby nathanroser » Oct 31, 2012 4:27 pm

Hmm, maybe that's what Bensons and Barytes caves in NY have so much of that stuff in the lower levels, a nearby mine has pretty large hydrothermal calcite crystals so that may explain it. Could also be a feature of the original depositional environment the limestone formed in since you can find layer of mud inside the bedrock sometimes.
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Re: How does limestone rot/corrode?

Postby Cheryl Jones » Nov 12, 2012 9:15 pm

struebe wrote:Someone once told me (and unfortunately I don't remember the details or who told me) that bacteria/microbes can munch on components of the calcium carbonate in limestone and basically destroys its structure. I haven't done fact-checking on this, but it seemed plausible enough I figured I'd share...


Hazel Barton has been studying this--I attended an excellent talk in which she explained the theory that microbes are/were needed for speedy and effective dissolution of limestone. She may have written a paper on the subject.

Hazel are you out there to provide a brief overview?

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