How can you tell a cave is gypsum??

[Neptuno]

I got some questions, I always think about it but looking at the ordinscaya cave again today here http://www.facebook.com/media/set/?s...1397311&type=3 I find some spots very similar to a new cave we recently started exploring, the pictures here doesn't really show it but some spots are almost identical http://www.dr-ss.com/media/gallery/O.../index.html#22 and here http://www.facebook.com/photo.php?fb...type=3&theater of course in smaller proportions, but the cave has layers of rocks and the rocks are very light and porous, is there any way to tell just looking that is or not gypsum?, is on the plan to get samples but not yet, just wondering......

[Squirrel Girl]

I got some questions, I always think about it but looking at the ordinscaya cave again today here http://www.facebook.com/media/set/?s...1397311&type=3 I find some spots very similar to a new cave we recently started exploring, the pictures here doesn't really show it but some spots are almost identical http://www.dr-ss.com/media/gallery/O.../index.html#22 and here http://www.facebook.com/photo.php?fb...type=3&theater of course in smaller proportions, but the cave has layers of rocks and the rocks are very light and porous, is there any way to tell just looking that is or not gypsum?, is on the plan to get samples but not yet, just wondering......

It's kinda hard to tell from photographs, especially underwater ones. With samples, it's pretty easy, though.

Gypsum can be finely laminated with annual varves, such as in the Castile Fm. in New Mexico. Another texture that gypsum/anhydrite can have is "chicken wire." I'm not sure any other rock has that texture. Those would be really hard to see on the scale of the photos you've posted.

Here's a link to some snaps I took in a dry gypsum cave a few weeks ago. You can really see the laminations in this bedrock.

http://www.flickr.com/photos/1017678...7627653024863/

[FW]

Gypsum can be finely laminated with annual varves, such as in the Castile Fm. in New Mexico. Another texture that gypsum/anhydrite can have is "chicken wire." ...

You might want to explain this a little. Cristian's primary language is Spanish, and I suspect 90% of American cave divers won't know either.

[LCF]

Isn't gypsum, even in crystals, very soft? I remember something about the Russian caves, that they had difficulty finding tieoffs because the rock would crumble.

[Jax]

You might want to explain this a little. Cristian's primary language is Spanish, and I suspect 90% of American cave divers won't know either.

Yes, please!

[TONY CHANEY]

Squirrel Girl, great pictures and really loved the Eagle fishing.

[Squirrel Girl]

Ok, so let's see. Varves are thin little layers, laminations, really that are deposited on an annual cycle. The form in sediment where there aren't critters around to burrow and disturb the layers. In the case of gypsum, it would probably be just too dang salty for critters. As mentioned, the Castile Fm. is a classic location and you can even see the layers in some places in the cave. The chicken wire texture, I don't have a photo of, but you all probably know what chicken wire fencing is, that's what gyspum bedrock can look like. It has little lines of non-gypsum (oxides or clays) that form kind of a mesh like structure. You *might* be able to see that in an underwater cave photo. But it's hard to tell. For instance, in the cave pictures I linked to, there are scallops on the wall that are part of the cave forming process and that can happen in limestone as well.

Yes, gypsum is a softer mineral than calcite (that forms limestone). However, all rocks are aggregates of mineral particles. It depends in part how well those particles (or crystals) are cemented together as to how "hard" the rock is. So you can have some *really* crumbly limestone. So hardness is not a very reliable indicator.

Tony, I see you've been poking around my Flickr site. I'm slowly adding to it. I was thrilled to catch that eagle snagging the giant fish. I have a new eagle site I'm hoping to get to in the next month or two. I've got my fingers crossed.

[Neptuno]

well... I cna't tell about chicken things... but even the pictures you posted looks similar to some spots, the russian cave totally looks like this one with the layers of roof coming down in big square chunks and the lines on the walls (layer lines)
there are some more pics in the facebook and the gallery, here http://www.facebook.com/media/set/?s...3921376&type=3 and also here http://www.dr-ss.com/media/gallery/O...use/index.html in case you didn't see them
I gues we need to wait till we get samples...

[Squirrel Girl]

well... I cna't tell about chicken things... but even the pictures you posted looks similar to some spots, the russian cave totally looks like this one with the layers of roof coming down in big square chunks and the lines on the walls (layer lines)
there are some more pics in the facebook and the gallery, here http://www.facebook.com/media/set/?s...3921376&type=3 and also here http://www.dr-ss.com/media/gallery/O...use/index.html in case you didn't see them
I gues we need to wait till we get samples...

I think you can find a lot of limestone caves with big square chunks of breakdown coming off the ceiling, too. Seems to me that in Kentucky, they have a lot of dry caves that have that.

A lot of sedimentary rock has layers. They come in all thicknesses, colors (well a wide range of colors anyway), and so on. That doesn't tell you too much.

At this point, I'd check a geologic map of the region and see if there's any gypsum bedrock in the area to see if it's a possibility.

[FW]

I am not sure they have "chicken wire" in the D.R., or Argentina for that matter.