Limestone Pavement = epikarst?

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Limestone Pavement = epikarst?

Postby hewhocaves » Mar 21, 2010 11:08 am

Quick question - is limestone pavement (specifically in streams) epikarst or the bedrock itself. Alternatively, it could just be unknowable or vary by location.

The place in question is here:
http://picasaweb.google.com/hewhocaves/ ... 7845482562

I'm going with epikarst. It's a single line in the thesis, so its no biggie either way :)
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Re: Limestone Pavement = epikarst?

Postby Spike » Mar 22, 2010 8:07 am

To me, Epikarst describes the uppermost bedrock where recharge is taking place. Some folks take it a bit deeper, but there is still a recharge/vadose zone. Without seeing the greater context of your photo, I really can't answer your question. All I can do is refer you to Klimchouk's paper and wish you the best.

http://www.speleogenesis.info/pdf/SG5/SG5_artId3263.pdf
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Re: Limestone Pavement = epikarst?

Postby John Lovaas » Mar 22, 2010 10:24 am

John-

Is the stream losing there? If it is, maybe it's just a swallet or stream sieve? And that feeds into the epikarst, but wouldn't be defined as epikarst. Storage seems to be a criteria that must be met. And every illustration of epikarst I've seen emphasizes the "highly corroded bedrock, residuum, and float". I sure don't see any residuum or float in the pictures of the mature epikarst in the Klimchouk paper Spike linked to!

The speleogenesis.info glossary entry:

A relatively thick (the thickness may vary significantly, but 15 to 30 meters thick is a good generalization) portion of bedrock that extends from the base of the soil zone and is characterized by extreme fracturing and enhanced solution. It is separated from the phreatic zone by an inactive, relatively waterless interval of bedrock that is locally breached by vadose percolation. Significant water storage and transport are known to occur in this zone. Synonym: subcutaneous zone.


and Google gave me the Kentucky Geologic Survey's description:

The interval below the organic soil and above the main mass of largely unweathered soluble bedrock, consisting of highly corroded bedrock, residuum, and float. Thickness varies from absent to a maximum of 30 meters (100 feet). The epikarst is relevant to the storage and transport of water in the karst system, and to foundation stability.
Last edited by John Lovaas on Mar 22, 2010 2:30 pm, edited 1 time in total.
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Re: Limestone Pavement = epikarst?

Postby driggs » Mar 22, 2010 2:14 pm

hewhocaves wrote:Quick question - is limestone pavement (specifically in streams) epikarst or the bedrock itself. Alternatively, it could just be unknowable or vary by location.

The place in question is here:
http://picasaweb.google.com/hewhocaves/ ... 7845482562


I thought this was an easy question until I looked at your photos and saw that you are specifically asking about the bed of an active stream...

Does anything count as epikarst if it is at/below the water table?

The word "epikarst", to me, implies more than just location, but also function: highly-permeable vadose recharge, soil-atmosphere-limestone interface (PCO2 increase), "karsty" erosion and dissolution, home to epikarst micro and macro organisms... I was content to call limestone pavement a special case of "dirt-less" epikarst until I considered it underwater.

I'm not even 100% certain that I'd call it "limestone pavement" if it lives beneath the water table, though I likely would if it were a dry streambed. What a nasty double-standard!

:shrug:

Disclaimer: IANAKS (I am not a karst scientist!)
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Re: Limestone Pavement = epikarst?

Postby hewhocaves » Mar 22, 2010 8:44 pm

All,

It is a losing stream. However, it is perennial in this potion of the reach.

How can anyone tell whether or not that's bedrock or residuum or float in the photo? Simply cause it's rounded and even doesn't mean it's bedrock. In fact, i think it looks more like epikarst the more I think of it.
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Re: Limestone Pavement = epikarst?

Postby l lambert » Mar 23, 2010 12:43 am

Bedrock
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