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winnph

My first whacked concretion (dud?)

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winnph

In preparation for a planned outing next week with my oldest son to hunt for fossils in the Lincoln Creek formation, I went to an outcrop of the local Blakely formation this afternoon, and now that I'm primed to spot concretions, I saw a few right away.  I only grabbed one to bring home (just had a small bag), but I may go back and grab some more later.  Since I lack the proper tools to prepare a fossil that's in a concretion (at least for now!), I just used my trusty hammer.

 

I'm not really seeing any fossil remains here, but it does have a really interesting funnel shaped part coming out of one side. Maybe it's some kind of burrow that later filled with different sediment? Or just purely geological? There's also a lot more of the center bit to expose, but I didn't want to keep whacking once it shattered, since I'll probably just destroy any fossil remains that are in there.

 

Anyone have any thoughts on this? Should I try to whack it one more time? Toss it? Secure it back together and save it for another day?

 

 

Concretion1.jpg

Concretion2.jpg

Concretion3.jpg

Concretion4.jpg

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winnph

I ran out of space for photos but here's one more closeup of the center bit.

Concretion5.jpg

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Plantguy

Interesting...I like breaking open rocks in general/concretionary masses as you just never know when you look inside...

 

I dont think you are going to find anything more by whacking it again....There are some different things in that central area that make me believe it might be more organic than geologic...could be a infilled burrow I suppose.  might even be some coprolite activity. Are all of the concretions you are seeing/finding similar in shape/composition and made up of this sandstone?

5ca96a40c5f27_Unknownsandstoneconcretionpanorama.thumb.jpg.9ecbe3235da5714f7bffe71a3a77d19f.jpg

I marked 3 areas in the closeup that stand out at least for me but may be just optical illusions and/or my trying to see something where there isnt anything.

1) seems to be a number of more small dark flecks (carbonaceous bits?) in the center than in the surrounding areas.  could be mineralogic. 

2) seems to be a linear/radiating pattern or ridges/furrows that could be something. could be just mineralogic.

3) seems to be a numbered small flattened areas, almost shelly molds/scale like that could be a trace of something or maybe mineralogic. 

 

So I'd hang on to it for now and look at some others and see if there is something similar in them that may help you recognize something more in this one. 

Good luck with your outing! 

Regards, Chris 

 

 

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winnph

Thank you! I did end up whacking it again because I am not a patient person, and was rewarded with a second "chamber" beyond the first one, connected via a small narrow passage. This is assuming what we have here is in fact a burrow, of course, but this overall shape does have me leaning that way until/unless someone convinces me otherwise.

There were only a couple other concretions in that area, and they were of similar size and shape, so perhaps some sand-burrowing small crustacean lived around here and a few of its burrows were captured? Maybe one of them with one inside?? One can dream...

second chamber.jpg

outline of 'burrow'.jpg

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winnph

Oh, forgot to include the photo of the "passage" between the two chambers, and also I forgot to mention originally that there is a small black mass within the concretion near the edge that looks like maybe bits of some kind of organic matter (second photo).

connecting passage.jpg

other matter in concretion.jpg

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winnph

Ok so this might be (probably is) crazy, but I was thinking about things that you see on sandy beaches that are roughly this shape, and suddenly this is what popped into my mind... could this be a poorly preserved fossil of some kind of giant kelp? I'm guessing it usually decomposes too quickly to be preserved, but maybe not always? And even if it did rot away, it might've left a cavity in the sand.  Just one of those dozing-off-in-bed ideas that I figured I'd share, especially since your handle is @Plantguy

Screenshot_20190406-235307.png

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Plantguy

Interesting....Something is going on there with the carbonaceous black bits...I'm not sure what--maybe plant remains or something else...but I dont see any recognizable structures in these photos... this looks like a pretty course dirty sandstone and the grains look sharp/angular--not sure of the environment there but reminds me of turbidite flow type stuff....are there other types of rocks...conglomerates...boulder/pebbles in any of the beds? I'm still wondering about the staining patterns and the possible burrowing/coprolite angle. Maybe some others have some additional thoughts...

 

FYI, my handle arose from what I'm called at work while taking care of tropical plants at businesses/residences. I have fun with fossil plants occasionally on the side. 

@GeschWhat

Regards, Chris 

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GeschWhat

Sorry for the late response. Some of these could be coprolites (possibly in burrows), but it is hard to tell without seeing them under a microscope. The fracture pattern of the item of interest in the first set of photos looks very much like what I see in carnivore coprolites that have fossilized as apatite. 

 

This one looks like it could be a cluster of fecal pellets from an arthropod - perhaps Favreinidae?

other matter in concretion.jpg

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Zenmaster6

Hi, from Puget sound. Avid fossil hunter.

I do want to say I know what sandstone you are dealing with. Almost every black streak and speck appears to be some sort of plant material in my experience.
However I do have 40 million year old shark teeth, fish teeth, gastropods, clams and plant fossils that are all within a 30 minute drive of Tacoma. They are out there! Good luck. (needed encouragement when I first started but it seemed nobody even knew there were fossils in Washington state :shakehead:

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