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I recently returned to hunt at my local Culpeper Basin creek site, and although the hunt was not incredibly fruitful, I did run across an interesting specimen. I have walked by this particular oddity many times and did post an image of it in my original trip report, but I remain very curious as to what this might be - if it is anything at all. To add some background information, I believe that the majority of the rocks exposed fall within the Balls Bluff Siltstone member of the Passaic Formation. All fossils that have been recovered thus far from the locality have been plant fossils, which may increase the likelihood that the specimen has a floral origin if it is a fossil at all. Here are a few different photographs of the specimen in question: I apologize if some of the photographs are not the clearest; unfortunately my phone camera tends to make the images noticeably less focused when I zoom in. Unfortunately, I forgot the specimen at the site when I left , but if more photographs are needed I would be happy to fetch it, scrub off the algae and dirt, and upload better photos to this topic. Hopefully it is possible to determine what this is, but it may be somewhat difficult since it seems quite water-worn like many of the rocks present at this particular locality. @cck, @Fossildude19, have either of you seen something like this elsewhere in the Culpeper Basin or elsewhere in the Passaic Formation? Thank you in advance to those who comment on this post.

A short while ago I unintentionally stumbled across a poorly preserved carbonized plant fossil at one of my favorite fishing streams - a place that I had never imagined would hold fossils. I posted an image of the specimen in the Fossil ID section where several members of the forum kindly confirmed my suspicions that it was a plant fossil. Here is the link to the original post in Fossil ID: @patelinho7 and I have been jointly looking into the Culpeper Basin (a Triassic rift basin within the Newark Supergroup) and its potential fossil content, and it seemed to the both of us that this could potentially be Culpeper Basin material. There were some red sandstones present that seemed to have originated from the Manassas Sandstone (a formation - or member? - within the Culpeper Basin) and the map that I inserted into the original post indicated that Bull Run Formation/Manassas Sandstone was exposed in the area where the specimen was found. However, further exploration of the site has led me to believe that the fossil originated not from the Culpeper Basin, but from Potomac Group (Early Cretaceous oxbow swamp deposits in Maryland and northern Virginia) sediments. From what I know, this could be very intriguing since the locality is in an area quite far from the traditional Potomac Group outcrop belt. However, I hope that this post and interpretations from more versed members of the forum will help establish whether these are indeed Potomac Group fossils. As a small forewarning, this will be a rather picture-heavy post. Aside from including a plethora of specimen images, I have also included images of rocks found at the stream locality in case they may help to interpret the site. Based on what I have gathered from the site thus far, my current working hypothesis is that I have found an area where a formation within the Potomac Group (hopefully someone more experienced with these fossils could shed light on whether they originate from the Patuxent Formation, Patapsco Formation, or Arundel Clay) overlies strata from the Culpeper Basin. However, this hypothesis is based solely on my observations and my limited stratigraphic knowledge and any revisions are very welcome. Before diving into the report itself, I want to thank everyone that has helped me thus far and that comments on this post. Your help and comments have greatly helped me on my quest and I would still be very clueless if it were not for this forum! To begin, I have included images of a few loose clasts that I believe may originate from the Culpeper Basin (from the Manassas Sandstone, specifically). The first specimen that I would like to mention is a piece of red, fissile shaly mudstone. The fissile nature of this specimen interested me most since most rocks I have encountered have been massive, often without clear bedding planes visible. Due to the locality being in close to the Manassas Sandstone according to the map in Dr. Weems's article (see map in the original Fossil ID post) I automatically assumed that it was one of the red sandstones from that formation. However, I have next to no experience with Potomac Group sediments and cannot say whether this may belong to the Potomac Group. Above are images of two more stones that are pretty good representatives of the general rock type found at this locality. The bottom one is another fissile mudstone much like that shown in the first image. The top specimen is a relatively flat slab of stone that seems to represent some sort of bedding plane. Loose flat slabs that resemble bedding planes are relatively common at this locality. Now, for a very shocking find! In my explorations I came across a very rare specimen of a fossilized Shoppingia cartdumpites. Unfortunately this specimen was what might be called a leaverite as it was far too large to take home and was located in relatively deep water . On a more serious note, I came across a specimen of very fissile red sandstone/siltstone. The thin layers of stone easily came apart, revealing very dark red stone within the specimen. The presence of this specimen seemed also to indicate that the Manassas Sandstone could be present at this particular locality. Now, for something a bit intriguing that could potentially represent a fossil. Unfortunately the lighting was not very good at this time of day, but there was an interesting inclusion in this piece of stone. Now, for a few more photographs before the fossils. They are a bit difficult to see due to the glare on the water, but these may be the source beds from which many of the flat bedding planes and perhaps where the fossils are coming from. I plan to add to this trip report as I continue to explore since there were a number of intriguing features that I did not photograph on my last outing. Here are a few additional things that could be important to note: 1.) When some of the rocks shown in the above photographs were flipped over, they bore a very dark red coloration. This reminded me of the oxidation that is present on some ironstones found in the Arundel Clay. 2.) Farther downstream there was a thick clay layer on the bank. This clay layer, which was composed of a whitish grey clay, was positioned between a layer of strata that coated the stream bottom and Pleistocene/modern soils. Now that I have posted some intriguing geological features, here are some photographs of the fossils that I decided to collect. Specimen 1: This is the original specimen that I posted in the Fossil ID section. Other members confirmed that it is a piece of poorly preserved wood. Specimen 2: More poorly preserved plant material. It is very hard to tell from the first photograph, so I have outlined the approximate shape of the plant fossil in the second photograph. The third photograph shows some carbonized material on the edge of the specimen. Specimen 3: An example of a stone containing a few carbonized plant elements. Stones with a few scattered plant elements are relatively common, though from my current explorations they seem to occur in rather localized areas. Specimen 4: Another indeterminate carbonized plant fossil. It is a bit larger than most of the specimens that I have found and the shape is rather different from that of most of the plants. Specimen 5: Three views of the fifth specimen: front (top image), bottom (middle image), side (last image). Specimen 6: This specimen probably represents one of the best preserved plants that I have found. However, I am not sure whether the specimen in the top image is preserved well enough to be identifiable. On the other side of the specimen a compressed plant specimen is preserved. It is difficult to tell from the photographs, but the fossil cuts diagonally across the bottom of the specimen on the lower image. Specimen 7: This plant hash plate is one of my favorite specimens of those that I recovered. Again, not sure if any members would be able to tell what these specimens may be. Specimen 8: I am entirely unsure what this specimen may be. I do not know whether these are fossils, impressions, mineral deposits, or some sort of sedimentary impressions. At any rate, the colors and depressions made for an intriguing rock. Specimen 9: A very large slab with some of the best preserved plant remains that I have recovered at this point. On one side of the slab (the first few photographs) an articulated plant seems to be preserved. This one is pretty intriguing... would any plant or Potomac Group experts have any ideas on what it may be? The other side of the slab (the last photograph) seems to contain what might be a poorly preserved plant.

Hello everyone, Recently I visited a golf course in Falls Church, Virginia - Fairfax county for any who are not familiar with that particular city. I recognized that I was likely to be on Culpeper Basin strata and noticed that there were numerous decorative boulders around the course. Due to their size I suspected that they had probably been sourced locally, and I took the opportunity to see if any might contain fossils. Although many of the boulders matched the Balls Bluff Siltstone rocks that I have encountered in my local stream site, I knew it was a stretch to hope for fossils and I kept my eye out mostly for carbonized plant fragments. After a while, I came upon one boulder that did not look radically different from those I had seen before - until I took a closer look. The boulder contained abundant impressions of what appear to primarily be brachiopods but which could also include some bivalves. Below are some photographs that I took of some of the larger fossils: Impression #1: Looks to be a brachiopod impression though I am not experienced enough in this area to rule out bivalve. Impression #2: Brachiopod? at the top right of the photograph and assorted material. Impression #3: Impression #4: Impression #5: Additional photograph of the boulder (apologies for lack of scale): Since it was a boulder I could not collect the specimen. As such, I cannot take more photographs of the boulder. Considering the fauna present on the piece I highly doubt that it came from the Culpeper Basin - as far as I know Unio sp. is the only bivalve known from Culpeper strata and to my eye these more closely resemble brachiopods. If they are not from the Culpeper Basin, where might the rock have been sourced from? The nearest Devonian-aged formations are the Mahantango and Foreknobs formations with the Needmore Shale being a bit farther away. Do the fossils or the rock resemble what one might expect from one of these formations?

Location: Loudoun County, VA (near Ashburn) Formation: Newark Supergroup —> Culpeper Basin Background: Okay! Here we go. Another track. I will preface this by saying that I don’t know if it’s Grallator, or very well may not be (or not a track at all). Here is how I found it in the field: I picked it up after seeing the middle toe. I didn’t really think much of it, except that it had a rough knuckle-y shape like my other print. Then, I noticed the roughly-three-toed shape. But I was only sold on it when I noticed the rightmost toe, and how pronounced it is. It really sharply but smoothly tapers off into a “claw”. Next, a shot in the sun with the ruler on my multi tool, and a closeup of the claw: The photos don’t do this toe justice to how prominently it is formed in the rock. Here are some low-angle lighting shots: And lastly, a brightened photo and the same photo with an outline of what I am looking at: Thanks for taking a look! At the end of the day, photo-ID of tracks are difficult so I will end up taking this along to Dr. Weems when I go to pick up my old track. But I will appreciate everyone’s insight regardless.

Hello all, I was wondering if anyone has had experience with tracks (specifically dinosaur, preferably grallator?) in red sandstone/mudstone. I recently turned my attention to the various types of red sedimentary rocks in the Triassic Culpeper Basin of VA because of successes I had many years ago looking for worm burrow traces in a group expedition. I was stopping off at construction sites near Ashburn and poking around for burrows or other small trace fossils and I unexpectedly found what appears to be a full blown Grallator track. I have to clean it and take proper photos before I make an ID post but I thought I’d ask about the possibility of this happening in redstones before getting my hopes shattered . It is very subtle and I wouldn’t have bothered picking it up if I didn’t spot a seemingly very obvious right toe and then the rest of the shape. In any case, I’m meeting with Dr. Rob Weems to pick up my old Cretaceous print so I will bring this along.

Hello all, Quick backstory on this: I’ve been researching the Triassic Culpeper Basin of VA for a little while now. I’ve been paying more attention to various formations I see when I’m around northern VA especially after reading more about the stratigraphy of the area from old papers. I’ve taken a special interest in this red mudstone (or is it siltstone or sandstone? I don’t know the exact difference to be honest) because it’s what I’m familiar with. I participated in this program as a kid with Dr. Peter Kranz where he took us all over the DC area during a week in the summer and one spot was at a construction site in Manassas, where we looked for worm burrow ichnofossils. Talked recently with @Andúril Flame of the West about this. I had a couple small specimens from that trip with what I assumed to be the burrows/other traces so I knew roughly what rock type and structure to look for. And there’s plenty of this red rock all over NOVA. So I figured I would look at whatever red rocks I see just in case it would have something. Today I visited family in Ashburn VA and looked at some of these red mudstone-like rocks in their garden. They had gotten them from spoil piles when the community was under development to add to their garden decor. I saw sedimentary structures on many of the rocks, but this was the most clear one with something interesting going on. Just thought I’d post in case someone has insights on what it may be. Thanks! Specifically, it’s the three-pointed marking on the rock. Is it a burrow trace, or maybe drag lines? It’s not a fracture or some other damage to the surface, the consistency of the rock surface changes and is almost like the soil was disturbed over that line and hardened as-is. apologies for lack of scale, didn’t have access to tools at the time and don’t have the specimen in my possession. (Ashburn VA, Culpeper Basin-Newark Supergroup)

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