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KimTexan

Memorial Day hunt. Site 2 Denton Creek. Paw Paw Formation? of Washita Group

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KimTexan

This is part 2, site 2 of my Memorial day fossil hunting trip.

 

You can see the site one report here:

I chose to drive out to Denton Creek north of Ft. Worth. I had been there before, but had not gotten to explore the area. It was the takeout point from a kayaking trip I’d taken down the creek a few weeks before. It took me 30 minutes out to drive out there from the first location I hunted in Benbrook. If you pass the creek going north you can go up to the next exit and then loop back to the creek. There is a little rock and dirt path off the shoulder of the road that leads down to under the bridge where you can drive your vehicle. The hill down to under the bridge is kind of steep. My car was a bit on the low side for getting over the curb and then a steep embankment with rocks. I bottomed out once. I thought I might park my car in the shade under the bridge, but when I arrived there was another vehicle in the area. I thought I was the only person crazy enough to be out here in the heat. Nobody could pass if I parked under the bridge so I pulled through into a small clearing there. The grass and weeds were grown up pretty high in the clearing.

 

I knew of a sizeable exposure on the creek that I wanted to try to get to on foot, but I didn’t know the terrain around the creek. I switched to my rubber boots for walking in the creek. I reapplied sunscreen and headed down the steep hill to the edge of the creek. I had to sit down and scoot myself over the edge and drop down to the rock ledge that ran along the creek. I inspected the exposure. Last time I was here I found a pretty decent Macraster obesus right by the spot I came in by. I didn’t see a single fossil.

 

The creek was maybe 40 feet wide give or take. The water was less than 10 inches deep where I entered the creek. I don’t think the creek is ever a high energy creek.  The rocks that are in this part of the creek are angular and jagged. The water in the creek is rather murky so you can’t see into the water. All of that makes it a difficult creek to walk in. Most of the creek in that spot is one level at bedrock with rocks scattered across much of the creek bottom. There is a narrow jagged rift in the bedrock that meanders along the creek bed. The water is deeper in the rift. I walked down into the creek and squatted down looking at some ammonite fragments in the creek. I saw two butterflies nearby. I tried to get a better picture from the side, but they flew away before I could do so. Sorry it is not a very clear picture. You can see the creek bed is kind of slimy looking. In some areas where the water was very low it looked foul and fetid. It had a green bubbly looking surface.

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I assessed the creek and decided to walked along the exposed rock ledge above the creek. As I walked up the creek there was a horrible stench of something dead. The further I went the worse it got. Finally I came upon a gar fish carcass on the rock ledge above the creek. It was close to one of the places where I had wanted to have a look around, but the odor was too strong and repulsive.  It looked to be just over 3 feet long. I can’t imagine how it got there. It had to be a person who had drug it there. This section of the creek does not seem deep enough for such a large fish to swim in. Maybe it swam in the rift though. There were deeper sections of the creek where it could live, but not here. There were signs of racoons all over along with remnants of their meals. Evidently gar is not on the racoon menu, which was surprising to me since it seems raccoons will eat almost anything else. I looked at the thin, razor sharp gar teeth. It is kind of scary to think that type of critter was in this creek when I kayaked it. I was in and out of the water all the time. A bite from that thing would be nasty. Here is a pic of it.

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I walked back down the creek upon the rock ledge to a place where there weren’t too many jagged rocks in the creek and where the rift in the creek would be narrow enough for me to step across it. Since the water was flowing slowly the rocks were covered with algae and were very slippery. I got to the rift. There were rocks pilled up there. I place one foot on a large one sitting at an angle and it tottered underneath me.  I made sure my foot wouldn’t slip and I balanced myself as I put my next foot on another rock. It tottered too. To slip and fall in this creek with all the jagged rocks would really hurt and might do considerable injury. At least when I slipped and fell in the NSR the riverbed was smooth, without any rocks.  I took a few more steps on similar rocks and I was I on smooth riverbed again near the other bank. I began to inspect the exposure. I found these just sitting on the bank. A cute little impression of an ammonite and what appeared to be a fragment of a Pinna clam. I have yet to find a whole Pinna clam. I’d kind of like to find at least one whole one someday. The only other formation I have found them is in the Goodland. It is another of the Washita Group formations.

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KimTexan

I found a curious piece of something that was curved lying in the creek bed. There were lots of burrows around, but this was not a burrow. So I picked it up. It had little pieces of what appeared to be shell imbedded in the item. Honestly the instant I picked it up the thought flashed through my mind that I had just picked up a piece of modern pre-coprolite, raccoon scat. In other words modern poo. Thankfully that was not the case here. It was hard as rock. Unfortunately I have picked up modern scat before thinking it was something else. Thankfully it has always been dry, but the thought of touching poo is disgusting. This piece was a fossil fragment of something, but what I didn’t know. The shape was unfamiliar to me.

 This is a picture of the exposure.

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I walked along looking at the exposure, but I wasn’t seeing anything. I thought for sure something would be here. I doubled back and walked over it again certain something of interest had to be there. Still nothing. Where I had intended to hunt was back up the creek so I had to make a third pass over the area. This time I began to see stuff. Every formation and exposure seems to have something unique about it. Sometimes it takes a bit for your eyes to adjust to seeing the formation the right way to be able to see the fossils. I’ve done the same thing elsewhere where my first pass there seemed to be nothing there, but upon my second or third pass I looked at it with different eyes and began to find stuff. That happened here. The fossils blend right in with the rock exposure and many are worn down so that the shapes are not as distinct. Here is an example of what I mean. There is an ammonite there. This is a close up of it. If you are standing up you would hardly notice it. It is missing part of it on one side, but the side in the rock looked a lot nicer. Not whole, but not half bad. Might not be a bad piece for the art idea or the table.

 

Man, don't you just hate it when you are looking at your in situ pics and see something you missed!  That just happened to me as I inserted the pic here. I can't tell you what it is or it will be a spoiler.

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I think this is the other side of the one above. I found 3 similar ones.

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Within a 35 foot section of the exposure I found 5 ammonites. All were removed quite easily. Luckily this section of the creek was in the shade. I had put on sunscreen earlier and reapplied it several times at the other location, but what I didn't realize is that I was missing and area on my back and I ended up with a sunburn where I had not been able to apply the sunscreen.

 

This little one is my favorite. Doh! Shoot, when I found this I thought it had been sitting there a while and had been washed there. I just realized that it had broken out of the rocks above it and the part that is busted off on the aperture looks like it is right there in the rock above it to the left. Some of the tubercles on this are very nice looking and prominent. I bet one of the larger tubercles that broke off is what stayed in the rock above with the aperture. I would have liked to have had that to glue back on. Even without it this was my favorite ammonite find of the day. 

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I decided to move on down the creek to try to make it to another exposure. As I walked to the lower layer of the exposure something caught my eye. It was a nautilus! I was so excited.  I could feel an little adrenaline rush. I was thrilled.

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I find several hundred ammonites or their fragments for every 1 nautili. I think I have found less than 10 nautili in all my years of hunting. I have only found them in the Paw Paw and Grayson formations so far. It would stand to reason that if they appeared in one formation within the middle Cretaceous that you’d find them anywhere you found ammonites within that period, but that has not been my experience. I have no idea why that is. Maybe someone can educate me on why we don’t find the nautili everywhere we find ammonites.

 

 

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KimTexan

I sat down next to nautilus on the ledge. I drank some lemonade left over from my lunch. I expected this to take a while. It was really hot, even in the shade. So, I decided to take off my rubber boots and work barefoot. I looked at the ground by my feet and saw a little echinoid. It was a bit crushed though. It was the first I had found in the creek. Here we go again. Looking at the picture here it almost looks like there is part of the echinoid to the right of where the rest is. Do in situ pictures drive anyone else crazy at times? But then again I have so many echinoids already. I don't think I have a nice whole one of this variety. I don't know the genus species, but I know I have this one in my collection already, just not any in great shape. All that I have found are a bit crushed or are only fragments. 

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I took my tools out of my bag and began contemplating my strategy for extracting it and tried to figure out where its borders were. I looked up still contemplating the matter and my eyes fell upon this 10-12 feet away to my left.

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I went and got it and proceeded to remove most of the surrounding rock with my hammer and chisel. That done I then I began to work on removing the nautilus. I did quite a bit of hammering to get it out. Thankfully the limestone was not that hard. It might have taken me 15 minutes at most. There have been times when I worked for over 2 hours to extract something and still didn't have it out because the rock was too hard. Having the right tools for the job is helpful too. Since the ledge had been exposed for quite some time there were cracks throughout the rocks around it and slabs of rock came out easily. The extraction was much easier than I had expected it to be and took a lot less time than I had anticipated. 

However, because the limestone was prone to fracturing, parts of the nautilus had fractured away from the main body and were still attached to larger chunks of matrix. I didn’t want to try to remove the matrix in the field so I put the large chunks in my bag. My bag was approaching the limit of what I could comfortably carry. This is one of the pieces that came off. It looks like it had been that way though since it had a layer of fungal mycelium on both pieces. The mycelium made for a pretty cool looking effect. If you zoom in it almost looks like an intricate shell pattern. You can see it best on the convex top portion on the left. The fungus dusted right off though. It was also on slabs of rock that I had removed trying to get to the nautilus.

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This is it once I got it out. It broke down a lot on what I believe is an outer whorl on the bottom of the pic above. Sorry the picture below the nautilus is rotated 180 from the shot above. I saved the pieces to glue back together. It is hard to tell what is matrix and nautilus though on the outer whorl.

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dinodigger

Beautiful ammonites!

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KimTexan

I stood up an dusted myself off and began to put my tools and fossils in the bag. I saw something in the ledge that made me curious. I stopped and walked over to it to look. I pulled my phone out to take a picture, but realized my phone was dead and I had not carried my power supply with me. Hum, seems like this scenario had played out before and I had told myself I wouldn't let that happen again, but there I was. At least my car was really close this time.

Oh I forgot to include this. This is a fragment off of the nautilus. The nautilus shell fragment is on the left edge. you can see a tan thin line. To the right is a Turritella cross section in calcite or some other crystal.

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There were fossilized burrows all over the place. These looked a bit like things that I had thought were burrows, which I had seen before, but the texture on the surface on this specimen was not that of burrows. It was smooth and had lines of bumps down the length of it.  I had never seen anything like it before. I was very curious as to what it might be. I got my hammer and chisel out and removed it from the ledge. I looked down and saw something similar just below it, but lose already and more worn. In retrospect I now wonder if some of the other stuff I had thought were burrows were actually these, which turned out to be crustaceans of some sort. I am leaning towards part of a lobster appendage. I have never found any lobster fossils before. So I am thrilled to have found some even if only parts.

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I think the curved piece I found and the one that was lose just below where I found this one are also lobster fragments. I have a fourth piece that could be part of an abdomen and tail, but I can't tell for sure, because it has matrix, oysters and other stuff all over it. I think the lobster parts are the coolest find of the day since it was new to me.

I suspect I may have been misidentifying appendage fragments as burrows in some cases when they are worn down or covered with matrix. 

 

All along I thought I was in the Duck Creek, because there was a light colored limestone and Mortoniceras, but I have never found a nautilus in the Duck Creek formation. I think I had said in an earlier post that I had never been hunting in the Paw Paw. I was mistaken. I remembered yesterday a trip to Roan Oak, TX where I had found 3 or 4 nautili in a creek. That it was the Paw Paw. I didn’t find out till I was out of the creek  that it was the Paw Paw. That leads me to think this is either the Paw Paw or the Grayson. I am leaning towards the Paw Paw. I can’t say that I am that experienced with hunting either of them. But when I have been in the Grayson the limestone/marl has been much harder than the rock in this place. Also, I tend to find Waconella wacoensis and a number of oysters one of which is Llmatogyra arietina. I had not seen either of those. Not that their absence excludes the Grayson though. The 3 formations mentioned thus far are all part of the Washita Group, so they are all found in the area just at different layers I guess.

 

Here is something else I forgot to include. I don't think this was concrete. It looks more like a piece of limestone with some serious trace fossils. I thought the ichno lovers might like it. I could be totally wrong about it being ichno. Anyone know what it is?

 

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I got packed up and put my boots back on. My pack was just right. I had to make two trips back to my car though. I had found a large Mortoniceras that I believe someone else had found and left behind. It isn't complete, but it could make a nice stepping stone for the yard if nothing else. It is right at 14 inches across.

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When I got in my car the temperature read 100 degrees. I knew it was hot, but not that hot. I rolled down the windows and drank the last bit of my lemonade and headed home. I stopped at a Braum's as is my end of fossil hunting tradition and got a small mint chocolate chip shake to finish Memorial Day off with.  

 

Thank you for reading my posts and I'd love to hear comments, ID suggestions and other info you may have wish to share.

 

Kim

 

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KimTexan
18 minutes ago, dinodigger said:

Beautiful ammonites!

Thank you. They are quite abundant in some areas here in North Central Texas. I'd be more than happy to take you out if you are ever in town to go hunting for some and my schedule allows. I'd rather be out hunting any day over most anything else. I've taken quite a few people out hunting for various fossils. I am no expert though. I just know how to find stuff. I've got a lot to learn though.

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Ludwigia

Thanks for the reports. Haven't had time to read them through yet, but I can tell from the nice photos that you've had quite a successful hunt this time around.

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Monica

I, too, like that nice little ammonite with the tubercles :wub::ammonite01:

 

And a big congratulations for finding that nautiloid!!!  Best of luck with prepping it :popcorn:

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JarrodB

Nice finds. 

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Ms Michal

Wowzer those were some very interesting finds. I've been getting the itch to grab my shovel and weed whacker ( lots of tall grass and weeds where I want to go) and go exploring some more on the property. ;) Thank you for sharing your story and espcialy your photos.

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Oxytropidoceras
On 6/5/2018 at 10:57 PM, KimTexan said:

Here is something else I forgot to include. I don't think this was concrete. It looks more like a piece of limestone with some serious trace fossils. I thought the ichno lovers might like it. I could be totally wrong about it being ichno. Anyone know what it is?

 

Could they be the external molds of evaporite minerals? Basically, what might have happened is evaporite minerals formed in lime mud in a coastal sabkha. The lime mud harder by semi-contempoaneous cementation and the evaporites minerals were dissolved out leaving molds of the minerals. I would hypothesized that the rock shows molds of crystals of stick-like (bladed) prismatic gypsum crystals.

 

look at Figure 8b of:

https://www.researchgate.net/figure/Carbonate-evaporite-mixed-sedimentary-facies-F1-and-F2-A-Inverse-graded_fig8_318434101

 

Yours,

 

Paul H.

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DPS Ammonite
4 hours ago, Oxytropidoceras said:

 

Could they be the external molds of evaporite minerals? Basically, what might have happened is evaporite minerals formed in lime mud in a coastal sabkha. The lime mud harder by semi-contempoaneous cementation and the evaporites minerals were dissolved out leaving molds of the minerals. I would hypothesized that the rock shows molds of crystals of stick-like (bladed) prismatic gypsum crystals.

 

look at Figure 8b of:

https://www.researchgate.net/figure/Carbonate-evaporite-mixed-sedimentary-facies-F1-and-F2-A-Inverse-graded_fig8_318434101

 

Yours,

 

Paul H.

I think that it might be plant material such as long leaves or stems. Slight curves of the structures suggest plant material over gypsum crystals. I found locally numerous molds of wood in the Paw Paw. Some still had coaly matter.

CE6BCEA5-19FC-4800-8A80-FF2EA8427490.jpeg

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Oxytropidoceras
20 hours ago, DPS Ammonite said:

I think that it might be plant material such as long leaves or stems. Slight curves of the structures suggest plant material over gypsum crystals. I found locally numerous molds of wood in the Paw Paw. Some still had coaly matter.

CE6BCEA5-19FC-4800-8A80-FF2EA8427490.jpeg

I agree. The same process can happen with plant matter with carbonate mud cementing around the plant material and organic matter removed by oxidation, rotting, or both. Maybe, they might be fossil seagrasses.

 

Yours,

 

Paul H.

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