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Utah oysters


The Jersey Devil

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Hello everyone,

 

I found these oysters while driving by in Utah along Cottonwood Canyon Road. I would really appreciate any help on the species and formation they came out of. The outcrop contained a lot of black sand.

Thank you.


 

General pic:

 

E1B1656A-263D-4570-92EB-C3288727310F.jpeg

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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Oyster 1:

 

 

A70BD833-57E8-4804-89DC-43CCF0026E7F.png

651F13EB-A09F-4569-AF49-63DBC8C10F75.png

DC68E677-C60B-4D2A-89A4-4DAC36C65589.png

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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Oyster 2:

 

 

048B7B8D-D02D-4905-ADD5-986E932CA782.png

D0BA9209-8688-42D9-A5E4-53D6C0FE2257.png

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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Oyster 3:

 

 

775273C8-7F86-4792-89BA-393411AF17DB.png

C2F164BF-4869-4751-8114-E50EFD07294C.png

CB6B93E9-D354-4ABB-8F25-17477AF0D62D.png

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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Oysters 4&5:

 

 

01931E4B-8E90-41AA-8C18-D3F7D6A979CE.png

270202DD-F818-4AD5-8C18-BCFA9089396F.png

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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They all looks like badly worn Exogyra oyster except for 4 & 5. 

 

These are my finds at NSR - North Sulfur River back in October. 

 

image.png.c65d3ca5880e54ce3a7022a242572da9.png

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36 minutes ago, Creek - Don said:

They all looks like badly worn Exogyra oyster except for 4 & 5. 

 

These are my finds at NSR - North Sulfur River back in October. 

 

image.png.c65d3ca5880e54ce3a7022a242572da9.png


Thanks. I suspected they were Exogyra. Do you think 4&5 could be Exogyra upper valves?

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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Looks like I found the formation I found them in. It’s the Tropic Shale.

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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That formation is middle to lower cretaceous.  It has lots of gryphea oyster, but not big as exogyra.   Pic 4 appears to be a thin outer shell that has been eroded.  Pic 5 is an interior shell piece.  

 

image.png.4a033d234544eea49b12e069344dc83a.png

 

This is the biggest exogyra I have found so far in Texas.  About 6 inches across (left to right) 3 1/2 inches from top to bottom.  About a pound in weight. 

Big  Exogyra.JPG

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  • I found this Informative 1

My goal is to leave no stone or fossil unturned.   

See my Arizona Paleontology Guide    link  The best single resource for Arizona paleontology anywhere.       

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2 hours ago, Creek - Don said:

That formation is middle to lower cretaceous.  It has lots of gryphea oyster, but not big as exogyra.   Pic 4 appears to be a thin outer shell that has been eroded.  Pic 5 is an interior shell piece.  

 

image.png.4a033d234544eea49b12e069344dc83a.png

 

This is the biggest exogyra I have found so far in Texas.  About 6 inches across (left to right) 3 1/2 inches from top to bottom.  About a pound in weight. 

Big  Exogyra.JPG


Is the Tropic shale a black color and kind of muddy? Just want to make sure I found the correct formation. The largest oyster pictured above is a little over 4”. Looks like Exogyra.

 

 

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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14 minutes ago, The Jersey Devil said:


Is the Tropic shale a black color and kind of muddy? Just want to make sure I found the correct formation. The largest oyster pictured above is a little over 4”. Looks like Exogyra.

 

 

According to Nautiloid.net "The Tropic Shale is the dark grey layer which begins at the base of the hard rock composing the steep cliff faces. It extends downward and is extensively exposed in the eroded flats." 

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I found some Pycnodonte newberryi  in the Mancos shale outside of Capitol Reef National Park. My blog post: https://viewsofthemahantango.blogspot.com/2012/06/pycnodonte-newberryi-from-utah.html

  • I found this Informative 1

-Dave

__________________________________________________

Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPhee

If I'm going to drive safely, I can't do geology. - John McPhee

Check out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/

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9 hours ago, DPS Ammonite said:


What do you think about the formation they came out of?

 

I remembered the shells technically came out of this harder brownish rock that was surrounded by that dark grey layer.

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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Well, I did a quick Wikipedia search and came up with this:  https://en.wikipedia.org/wiki/Tropic_Shale

 

Quote

The Tropic Shale has been correlated temporally with the Tununk Member of the Mancos Shale in central Utah, the Allen Valley Shale of the western Wasatch Range in Utah,[4] the Mancos Shale exposed at Black Mesa, Arizona, and additionally the Bridge Creek Member of the Greenhorn Limestone at Pueblo, Colorado. Bentonite layers present in all these formations have been correlated throughout deposits associated with the Western Interior Seaway.

So you are probably right but I can't find a good geological description of the formation at the moment.  The Geological map of Utah does not go into formation names but shows Jurassic rocks to the west of Cottonwood Canyon Rd., and Cretaceous rocks to the East.   The area around Grosvenor's Arch, which is off Cottonwood Canyon Rd. is known to have fossil oysters lying on the surface, according to some old collecting site info.

-Dave

__________________________________________________

Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPhee

If I'm going to drive safely, I can't do geology. - John McPhee

Check out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/

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51 minutes ago, Shamalama said:

Well, I did a quick Wikipedia search and came up with this:  https://en.wikipedia.org/wiki/Tropic_Shale


 

 

So you are probably right but I can't find a good geological description of the formation at the moment.


Are you saying that the hard brownish rock the oysters were found in might be part of the Tropic shale?

I was thinking maybe they are actually from the formation that underlies the Tropic shale, the Dakota formation.

“You must take your opponent into a deep dark forest where 2+2=5, and the path leading out is only wide enough for one.” ― Mikhail Tal

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10 minutes ago, The Jersey Devil said:


Are you saying that the hard brownish rock the oysters were found in might be part of the Tropic shale?

I was thinking maybe they are actually from the formation that underlies the Tropic shale, the Dakota formation.

Without seeing it for myself, or a more detailed geologic map, I can't say for sure.

-Dave

__________________________________________________

Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPhee

If I'm going to drive safely, I can't do geology. - John McPhee

Check out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/

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