Fossil and rock identification

austinuni

That's exciting! You gave a lot of good information to help track it down. Any more info on the swimming yams?

Evo

Notice the empty indentations? That's where yams fell out.

Normally, the fossils are the usual hard white substance. But I have found a large number of rocks recently where the fossils are of a soft, crumbly orange substance. These are all from this area, both the white and the orange. I'm wondering what the orange yam like fossils could be.

Here's an orange fossil of possibly a crinoid?

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Evo

Can anyone identify this type of rock and what caused the pits?

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Andre

A guess, maybe those are calcite etch pits

Calcite (if it's that) will dissolve slowly in rain water (chemical weathering) which is slightly acid (due to carbonic acid - dissolved carbon dioxide) and little dents may grow out to pits. There is not a lot of literature about it.

http://www.limestone-pavements.org.uk/geology.html
http://www.essc.psu.edu/~brantley/pu...slocations.pdf

DrDu

A coral may be?

Evo

Thanks, both of you. I've been reading that similar holes are formed in rocks when iron ore they contained dissolved. Iron might also explain the reddish discoloration on the rock surface. I'm still searching, the rock is heavy, solid, and very hard, so far, I've ruled out calcite.

I have more rocks I need to post so please keep the ideas coming.

dlgoff

Okay. I finally bought a "point and shoot". Here's my first two photos.





All of these where found in Arkansas with the exception of the middle one on the bottom row of the first picture, which was found in Kansas.

Evo

Very nice dl!!

chemisttree

This looks like a textbook example of 'tafoni' weathering in rocks. This type of weathering pattern occurs in 'case hardened' rock where the hardened outer surface is somewhat more reisitant to weathering than the softer interior. Nice example.

Evo

Oooh. Now I will have to photograph the huge rock slabs that are pockmarked, I'll post some tomorrow, it's getting dark.

chemisttree

Evo,
You taking a geology course? I sure hope we're not doing your homework for you.

Evo

LOL! No, I've always had a love of rocks and fossils and now find myself sitting on top of an enormous fossil bed.

Evo

This gives you an idea of the density of the fossil layers.

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Ms Music

Lucky!

I have 4 days off work, (Thurs - Sun) so I will either a/ forget this thread completely, or b/ remember and post some pictures. Is it okay to post pictures of collections in this thread even though it is called "fossil and rock IDENTIFICATION"? Or should I use the old thread?

Evo, your swimming yams reminds me of one day at the ocean. There was a walkway cut through a small sand dune, and part of the dune also had collapsed to show the interior. Although it was sand, there were these orange clam looking blobs in the sand same as your picture. I always wondered how you could get orange blobs of sand mixed with normal sand. Probably completely different, but they look the same as your picture, none the less.

Evo

Collections are definitely ok.

I wonder what they are?

cousin it

That is not "tafoni" weathering. I agree with the earlier respondent that it is some kind of cnidarian. Take a hammer and give it a good whack... let us see a fresh surface.

cousin it

A ventral and a dorsal of an asaphid trilobite(Isotelus gigas).
Ordovician of Kentucky