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South Texas Upper Cretaceous Tree


CraigHyatt

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A beautiful split concretion embedded in a block of hard sandstone. Probably not a tree, but seems to have growth rings and outer bark.

post-20989-0-19408300-1463930281_thumb.jpeg

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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My guess would be that at the center was (is) an iron-bearing material, and successive saturations with water and drying caused the iron to leach out in these rings each time. Are you familiar with TLC (Thin Layer Chromatography)? The rings have that characteristic, of having the water transport the material through the medium, and creating a gradient of material deposited each time.

I wonder what the object in the center is?

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Don't know TLC. Sounds something like electrophoresis?

Edit: I mean the diffusion part, not they are literally the same.

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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...thing in the middle...

Left as an exercise for the interested student.

This student ain't interested in carrying a 200 lb rock. That's too much exercise.

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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My guess would be that at the center was (is) an iron-bearing material, and successive saturations with water and drying caused the iron to leach out in these rings each time. Are you familiar with TLC (Thin Layer Chromatography)? The rings have that characteristic, of having the water transport the material through the medium, and creating a gradient of material deposited each time.

I wonder what the object in the center is?

I was secretly hoping it was a tree.... I might have a chance to find something besides ammonites and oysters. ;-)

Also notice how the core shape rotated with successive saturations. That means there's a porosity gradient in the surrounding stone. Of course it wouldn't be perfectly uniform.

Thanks so much for all your great explanations. Learning a lot here.

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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Isn't the formation you are picking through a marine environment?

You should count yourself lucky to be finding what you have. There are fossil starving people in some locations, you know. :P

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Isn't the formation you are picking through a marine environment?

You should count yourself lucky to be finding what you have. There are fossil starving people in some locations, you know. :P

Ha ha ha. Yeah, I should count my blessings. :-D

This area was marine, but finding a tree would mean a layer where the water had receded.

https://en.m.wikipedia.org/wiki/Western_Interior_Seaway

Info: Craig Hyatt, retired software/electrical engineer

Experience: Beginner, fossil hunting less than a year

Location: Eagle Pass, TX USA on the border with Mexico, hot dry desert

Formation: Escondido, Marine, Upper Cretaceous

Materials: Sandstone, Mudstone, Shale, Chert, Chalk

Typical: Thalassinoides, Sphenodiscus, Exogyra, Inoceramus

Reference: http://txfossils.com/Txfossils.html

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