Culpeper Basin Plant Fossil?

[Andúril Flame of the West]

Early last month I made a post regarding a specimen that I had recovered from the Newark Supergroup that I had thought could be a possible trace fossil. After discussing the find on the forum and contacting some experts on Newark material, it was determined that the specimen was in fact not a fossil. However, this find greatly increased my interest in the fossil content of the Culpeper Basin. 

 

Today I decided to visit one of my favorite streams with the intent of fishing - but I could not help checking out some exposed rocks, knowing well that the stream would cut through Newark strata. As a point of reference, I have included a map of the component formations of the Culpeper Basin that occur in northern Virginia. The red circle is approximately where the specimen in question was found, so it could have come from either the Bull Run Formation or the Manassas Sandstone. 

 

 

Weems, R. E., Culp, M. J., & Wings, O. (2007). Evidence for Prosauropod Dinosaur Gastroliths in the Bull Run Formation (Upper Triassic, Norian) of Virginia. Ichnos, 14(3-4), pp. 271-295. https://doi.org/10.1080/10420940601050030.

 

 

When checking out the rocks I was simply hoping to learn something about the exposed strata that might indicate the formation present. However, I came across the intriguing specimen pictured below. I have not heard of any fossils coming from this particular area, so I am not sure whether the fossil is what it appears to be or whether it is something entirely different. 

 

 

A view of the entire specimen with the suspected carbonized plant material at the top end. I apologize for the poor picture quality. If better photographs are needed for identification, I would be more than happy to provide some in natural light. 

 

 

A closer image of what may be fossilized plant material. I believe that plant material has been recovered from the Bull Run Formation (where this specimen likely originated) so it could very well be a plant imprint. I know nothing of botanical terminology, but the horizontal lines across the specimen appear to be consistent with what might be expected from carbonized plant remains. It should also be noted that the specimen was found as a loose clast, though it was found among an abundance of very similar material. 

 

 

Hopefully this last photograph provides the necessary detail to properly evaluate the specimen. Again, if more photographs are needed be sure to let me know. 

 

Thanks in advance to everyone who comments on this post .

 

@cck @EMP @Fossildude19

[Rockwood]

I agree that this looks like a remnant of poorly preserved wood. A mold left by carbonized wood might be a good description. 

[Fossildude19]

Definitely plant matter of some sort. Not sure of what, though.

Could be a part of a poorly preserved horsetail/Equisetum or just a branch/rachis of some other plant.

Cool find, either way.

 

Cropped, rotated, sharpened, and contrasted:

 

[Rockwood]

That looks more like the fractures that are seen in wood to me.

[patelinho7]

Oh wow! What a great start to my day, seeing a post of yours show up. You’ve hit the jackpot, my friend! (For context: @Andúril Flame of the West and I had been discussing the VA Culpeper Basin for a little while because a lot of the old productive sites are gone nowadays). This is great news! And great use of that map. That is my favorite map right now .
 

I agree, looks like wood, almost similar to stuff I’d pull out from the Potomac group. Also, it personally looks like Bull Run formation rock type, as I think Manassas Sandstone is always red. You’ve got a great place to start from since you’ve now got an eye for the right rock type and a possible productive location! I wonder if there’s any fish material there. Pretty much all the old localities have reported fish bits with wood/plant material.

 

Great report! Looking forward to future visits/posts!

Edited June 3, 2023 by patelinho7

[patelinho7]

Oh wait. Specifically, I’d say it looks like the Balls Bluff Siltstone Member of the Bull Run Formation, which may rule out the chance for fish remains or tracks… I’ve perused so many Dr. Weems papers I can’t remember anymore what you can find specifically in that member… I’ll figure it out at some point 

[cck]

Nice find! Looks similar to some wood chunks I’ve found further south in the basin… Now you just have to uncover tracks and fish and teeth!

[Andúril Flame of the West]

Thanks to everyone for the quick replies! I am very glad to hear that it is indeed plant material and am still quite surprised that I stumbled upon this where I did. I've visited this stream for years and it happens to be within walking distance of my home, so a more thorough exploration of any exposed material should come along shortly .

 

6 hours ago, Fossildude19 said:

Definitely plant matter of some sort. Not sure of what, though.

Could be a part of a poorly preserved horsetail/Equisetum or just a branch/rachis of some other plant.

Cool find, either way.

 

I appreciate the feedback @Fossildude19. I doubt it is identifiable due to the poor preservation and fragmentary nature of the fossil, but hopefully I'll have the chance to uncover some larger and better preserved specimens in the future. 

 

5 hours ago, patelinho7 said:

Oh wow! What a great start to my day, seeing a post of yours show up. You’ve hit the jackpot, my friend! (For context: @Andúril Flame of the West and I had been discussing the VA Culpeper Basin for a little while because a lot of the old productive sites are gone nowadays). This is great news! And great use of that map. That is my favorite map right now .
 

I agree, looks like wood, almost similar to stuff I’d pull out from the Potomac group. Also, it personally looks like Bull Run formation rock type, as I think Manassas Sandstone is always red. You’ve got a great place to start from since you’ve now got an eye for the right rock type and a possible productive location! I wonder if there’s any fish material there. Pretty much all the old localities have reported fish bits with wood/plant material.

 

Great report! Looking forward to future visits/posts!

 

I'm glad you enjoyed reading this post! I am still quite shocked that I found this on my first exploration of the Culpeper Basin, especially at a location that I could easily walk to at any given time. I agree that the map is very useful and I owe you a special thanks for pointing me toward that paper in the first place. Most maps that I have seen usually label the area simply as Culpeper Basin or Newark Supergroup without anything more specific, but that map certainly gives a lot more information about the exposed formations in the local area. 

 

Now, with regards to the stratigraphy I did notice a number of interesting things at this site. The rock in which I found the fossil, which may be Bull Run Formation, was in the minority. The most abundant sedimentary rocks were large, loose bedding planes of a reddish brown mudstone/siltstone. I believe that this is Manassas Sandstone due to the red coloration (I was able to break apart a few smaller chunks of this reddish siltstone and the inside was a dark red rather than a drab reddish brown as it was on the outside). At least a few of the slabs I came across had intriguing patterns that seemed reminiscent of markings that might be made by a paleocurrent, perhaps in a lacustrine or fluvial environment (as I believe the Culpeper Basin was mainly deposited in both these kinds of environments). There were also sedimentary rocks with a very similar red color, but they were fissile and flaked away almost as shale would. I am not sure if there is a difference between these and the similarly colored mudstones that seemed to be more massive? (excuse my poor use of terminology, hopefully this term has been correctly applied). Other than the sedimentary rocks weathered (quartzite?) clasts were present in abundance with a yellowish-brown coloring. I vaguely remember that quartize clasts are known from some members of the Newark, possibly the Reston or Leesburg conglomerates. So the presence of all these different rock types has certainly made things a bit more complex than I had anticipated.

 

I am sure most of what I said was not worded the best and it is difficult to lay all my thoughts out without photos to accompany my observations. But not to worry! Soon I will return and I will compile a trip report with abundant photographs in hopes of sorting out the stratigraphy of the area. I also look forward to seeing what you find in the future. I am sure there is still a lot out there for the both of us to uncover .

 

3 hours ago, cck said:

Nice find! Looks similar to some wood chunks I’ve found further south in the basin… Now you just have to uncover tracks and fish and teeth!

 

Yes, that would certainly be the hope. Considering how little exploration has occurred in the Culpeper Basin, especially in its northern reaches there could be some interesting fossils to uncover in the future. While checking out the mudstone/siltstone slabs I cannot say I wasn't looking for tracks ... and that I wasn't having a challenge avoiding the influences of pareidolia .