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Mudstones?


Scarletfemale

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Scarletfemale

Hello all-

 

I live in NC, the far Western part, but spend a lot of time in TN, at a man-made lake that was constructed as part of the TVA project, beginning in the 30s. 
 

The rocks and scenery around there have been stirred up and relocated with the construction of the lake, so it’s kind of difficult to say what ought to be where. That said, they consist mostly of rather uninteresting dolomite and quartzite in the forested areas, and then huge beach expanses of orange-tan to red to purple and even bluish clay-type slate or shale material that has hardened in spots to near-rock consistency. There are beautiful agates to be found in some banks of red clay, however, and there are also enormous, opaque, gray mudstones with intriguing shapes. I thought at first that the mudstones were some of the most boring-looking things I’d ever seen, with the utter lack of variation in their color, as if painted in dull, chalky gray, but that has changed. 
 

After attending several summers of lake recreation, I noticed that the rocks were becoming much more interesting, and paid more attention to them. It seemed that the mudstone was sloughing off of itself at a considerable rate, and that the materials that formed the center of the nodules were becoming exposed! The mudstone is gritty and slips off with repeated exposure to bioturbation, (I believe this is the correct term for tumbling by elements, no?), and as time passes, more and more fascinating things are turning up. Not all of the nodules contain a center item, but many do. 
 

Following a bit of research, I located this article:

 

https://www.sciencedirect.com/science/article/abs/pii/0031018281900572

 

...and some others that also describe fossils being found in the middle of such mudstone formations. What really surprised me was how identical to my setting the soils and rocks sounded in the article...

 

Here are some photos of things that have come from the mudstones...

 

Anyone have any thoughts on what these could be? 

27D9B2C3-5842-43EC-B986-2D2A7A6B4C5A.jpeg

9CC144D6-B8BE-4711-BD6B-8D3AB4DC5EBA.jpeg

F3691E25-D2C4-4FA1-AD42-B56F7D5D2E87.jpeg

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Scarletfemale

Rats. Those photos are so small that there’s not enough data to really show the texture. If anyone would like further shots, let me know. I also have several other items but figured I’d see how these went first. 

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Are you posting images from a smart phone? Possibly you have higher resolution imagery on your phone but they are being downsized when you post them. There is a MB limit to the images in any individual post but you can reply to your own post to include additional larger images to work around this limitation.

 

The (small) images above all seem to be natural shapes for weathered rocks and do not appear to show any evidence of fossils. It is possible there may be fossils included in these rocks that we just can't see the details of with so few pixels. If you are wondering if the interesting shapes of these rocks may be hinting at them being fossils, then no, I don't see any indications of recognizable fossils among your assortment of rocks.

 

 

Cheers.

 

-Ken

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Scarletfemale

Here are some more things to come out of the mudstones:

 

 

 

I could totally believe that weathering could cause such shapes, but the thing is, unless they were weathered prior to being encased, this is the first exposure to the elements that these layers have had. Until rather recently, all of these were coated in a thick rind of opaque gray material, which I take to be mudstone. I’ll have to find some that still have the stuff all over them to show what I mean. 

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23 minutes ago, Scarletfemale said:

I could totally believe that weathering could cause such shapes, but the thing is, unless they were weathered prior to being encased, this is the first exposure to the elements that these layers have had.

Keep in mind that rocks can have a long history. Rocks can erode and re-cement into new forms over geological time. You can get interesting shapes inside rocks in various conglomerates like breccia.

 

https://en.wikipedia.org/wiki/Breccia

 

Weathered bits of rock accumulate and are cemented together into new solid forms with interesting internal structures. These are still the result of purely geological forces and have no biological origin that would classify them as fossils.

 

I'm seeing lots of interesting patterning in your rock images above. They all appear to be cracks filled with mineral intrusions. While these types of rocks often make very nice polished specimens after some time in a rock tumbler, I'm not seeing anything to indicate traces of organic lifeforms in any of these so at the moment these appear to be interesting rocks but not fossils.

 

 

Cheers.

 

-Ken

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