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Roadrunner

Finds Today That I Can't Id

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Roadrunner

These boulders are probably the result of some geologic process, though I did find a nice trace crinoid next to one.

I've seen this material typically covering limestone (always thought that it was probably lava) - but had never seen it protruding out of limestone in knobs and other shapes before.

Any ideas?

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....and the trace crinoid beside it - about a 25 pound rock by itself.

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I also found a nice piece of petrified wood that I haven't photographed yet.

Edited by Roadrunner

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Roadrunner

This is most likely still geological - but I couldn't resist going back to knock one or two of those nodules out of the boulder. It took me 2 trips to find it again, since I have no GPS and just have to "follow my nose," as my Dad used to say.

Here it is again - before I took my rock hammer to it;

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The knobs came out - mostly whole. They were also limestone, though a much finer grain of it than the rest of the boulder. And the black coating was sheet thin.

After I hammered the nodules...

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The area on top is harder to see - though if you look closely you can see that taking out the knob it left a hole in the boulder.

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The knob leaving a hole on the bottom was easier to photograph, due to the setting sun.

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I posted this is a geology forum, but no one has been able to explain how this process may have occurred. At first they thought it was just limestone being eroded away from the nodules. But no one can explain why the holes, or the finer limestone making up the nodules.

I'm getting pictures of the hammered out nodules today.

Of course, limestone is sedimentary and could have been deposited somehow underneath and around the nodules, but finding the nodules also limestone - just finer grained and with the black coating?

Any ideas? I'm stumped.

Edited by Roadrunner

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tmaier

Could it be that the nodules are mudstone? Blobs of mud that became deposited in the sedimentary limestone?

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Roadrunner

Could it be that the nodules are mudstone? Blobs of mud that became deposited in the sedimentary limestone?

Thank you for the thought - I'll try researching that angle more on the internet. :)

I'm looking for any and all ideas, so please keep them coming!

Edited by Roadrunner

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Missourian

Most likely, the sediment was all the same at first. During diagenesis, the concretions began to form as some mineral (hematite?) began to crystalize around some nucleus (fossil, burrow, non-organic irregularity, etc.). This could have occurred before or after the surrounding limestone crystalized into its current state. If before, the crystals continued to grow through the pores of the sediment. If after, the mineral replaced the calcite as it expanded outwards. The 'rind' remaining in the boulder is probably related to this mineralization 'front'.

Edited by Missourian

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Auspex

At the bottom of the last image, where you've broken-off a "knob", I see a rind. This is a concretion, formed during diagenesis.

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Roadrunner

Most likely, the sediment was all the same at first. During diagenesis, the concretions began to form as some mineral (hematite?) began to crystalize around some nucleus (fossil, burrow, non-organic irregularity, etc.). This could have occurred before or after the surrounding limestone crystalized into its current state. If before, the crystals continued to grow through the pores of the sediment. If after, the mineral replaced the calcite as it expanded outwards. The 'rind' remaining in the boulder is probably related to this mineralization 'front'.

At the bottom of the last image, where you've broken-off a "knob", I see a rind. This is a concretion, formed during diagenesis.

Thank you - diagenesis makes more sense than anything I've heard or read yet.

Your help is appreciated. :)

I'll still post pictures of what I broke off of that boulder - my camera battery died today, so it is recharging.

Edited by Roadrunner

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Roadrunner

Missourian and Auspex - I'm only putting in these pictures because I said that I would. Thank you for your input on this, especially with this not being a geology forum. Here are the nodules - sorry about the shadows;

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Edited by Roadrunner

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Roadrunner

I found this a few days ago in a huge boulder;

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The boulder is way too big for me to extract it with the tools that I have.

..and though I don't know the type of gastropod that it is - it got me to thinking, I'm not THAT far from the Rio Puerco Valley - geographically, and geologically speaking.

Then I found the small rock/concretion below - which suggests a gastropod;

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Or, it could just be a rock. :) But "live" it even looks more like a potential gastropod.

I have no idea how to begin "looking into it." We are considering buying an air scribe - but that isn't going to happen any time soon. I have an engraver, and I know that I should start practicing with it - possibly on this thing, below. I have NO idea what it might be!

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Then after finding a new rock outcrop with my binoculars and climbing up to it, I found the large concretion below - which is also suggestive of a gastropod;

It's about a foot long and I was having trouble getting pictures of the side of it. It looks pretty unremarkable in the pictures, but again - it has some promise;

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The best side picture of the back (it is leaning against my leg). It weighs between 30 - 40 pounds.

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Believe it or not - I've washed this rock already. But the breccia is cemented on. So I have it soaking; From there I'm not sure where to start!

Then I found this very close to our house. I think it is a Chaetetides, (large coral) and they have been found in NM. But that is just a guess. Sorry that I had to take the pictures in the shade, it probably weighs about 100 pounds.

You can barely see the whorls in the front on this first picture;

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One side of it is eroded, and the other not so much; We will be moving this to the sunnier side of the house for better pictures.

Edited by Roadrunner

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Roadrunner

A "pudding rock" with lots of what looks like clams;

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And finally, this little unremarkable guy - I think a small piece of a baculite, very eroded and in bad shape. It is hard to see the whorl on the end and it has gotten cloudy, so I put it against white paper and held it for the second view. I found it just below the rock outcrop where I picked up the 30 - 40 pound concretion.

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Edited by Roadrunner

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Roadrunner

So - does anybody know somebody in the Albuquerque area where I could go for some fossil preparation lessons? :D

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Missourian

The boulder labeled 'chaetetid' above did strike me as resembling some I've found. Does it have the fine, hair-like structure and texture? See:

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Some more examples from my adventures:

http://www.thefossilforum.com/index.php?/topic/32414-hunting-for-chaetetid-sponges/

http://www.thefossilforum.com/index.php?/topic/25240-pennsylvanian-sponges-from-kansas-missouri/?p=447170

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Roadrunner

The boulder labeled 'chaetetid' above did strike me as resembling some I've found. Does it have the fine, hair-like structure and texture? See:

attachicon.gifpost-6808-0-82870200-1351460679.jpg

Some more examples from my adventures:

http://www.thefossilforum.com/index.php?/topic/32414-hunting-for-chaetetid-sponges/

http://www.thefossilforum.com/index.php?/topic/25240-pennsylvanian-sponges-from-kansas-missouri/?p=447170

Thanks for the response. I'll have to check it when I'm home during daylight hours - might not be until the weekend. I'll certainly look!

You have some great finds in your chaetetid thread. I also surmised from the direction the corals grew, that they were on top. Their direction looks as if it was influenced by water current.

I'll also get some close-up pictures of the coral that grew on it.

Any recommendations about who I should ask about the potential gastropods? I'm not getting much traffic through here, and wasn't sure if I should just start a new thread. I'm so new at this and I'm finding so much - I hate to be creating a bunch of random threads.

Edited by Roadrunner

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Missourian

You have some great finds in your chaetetid thread. I also surmised from the direction the corals grew, that they were on top. Their direction looks as if it was influenced by water current.

I'll also get some close-up pictures of the coral that grew on it.

Any recommendations about who I should ask about the potential gastropods? I'm not getting much traffic through here, and wasn't sure if I should just start a new thread. I'm so new at this and I'm finding so much - I hate to be creating a bunch of random threads.

Thanks. The growth form of chaetetids, as with stromatolites and massive coral, was probably due to the particulars of the immediate microenvironments. Domes and columns probably indicate some process interrupted what would have been a continuous sheet.

As for the potential gastropods, I'm not sure. For the moment, I can't see anything definitive.

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Roadrunner

Thanks. The growth form of chaetetids, as with stromatolites and massive coral, was probably due to the particulars of the immediate microenvironments. Domes and columns probably indicate some process interrupted what would have been a continuous sheet.

As for the potential gastropods, I'm not sure. For the moment, I can't see anything definitive.

They are all quite interesting. When my husband asked what it was that he was helping me carry, I replied ' "I don't know - but it was organic!" I had happened to see chaetetids when I was reading about stromatoporoids via my other thread "....My First Mystery." But I didn't get a real overall look at the shape until we got it home. so I have more homework/investigating to do with that, too.

As for the concretions - what would you start "chipping away" at them with? The small one seems rather fragile - and the large one is anything but fragile. I'm almost positive that I'm going to find something under all that rock, but it is nearly impossible to convey all about their shape(s) with photographs.

Edited by Roadrunner

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Wrangellian

I am not sure that your concretions give any sign that there is anything in them. Most of the concs around my collecting site are empty, such that I don't even bother breaking them open unless there is some sign. They can be really tough, so even doing that can be a lot of work! So if that's the case in your area (most empty), it might be too much work to bother going at them on spec with a more intensive/expensive/tedious method of working on them until you are sure there is something inside. I would try breaking them open first and if you see something, glue it back together and then prep it - that is if whatever you see doesn't look OK just broken open.

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Missourian

I do have a 'rule of thumb' for concretions. If not sure about concretions in a formation, tap some with a rock hammer. If there is something inside, more likely it will split with little effort. An empty one will be tougher to crack. This 'rule' is by no means foolproof, but is a time-saver.

Edited by Missourian

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Roadrunner

Thanks' guys!

Sorry for the late reply....just got home tonight.

I sure do appreciate the advice. :D

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