Mazon Creek trips

[Anomotodon]

Just got back today from my first trip to Mazonia-Braidwood (pit 11) this year! I unfortunately couldn't make it on the opening weekend, and was afraid we won’t find anything this late - but I ended up being pleasantly surprised. By this point I ran out of concretions to freeze-thaw from last year, so I’m very excited for the next few months 

 

We decided to go back to the Tipple hill area. Here is what it looks like now - open, barren fields of rocks 99.9999% of which are not what we are looking for. What I found especially challenging about this area, is that there are numerous concretions that have perfect shapes, but are not actually the right type of rock - yellow/light orange. I haven’t seen them at other places within Mazonia. I tried cracking a few last year, but they just have quartz (?) crystals on the inside. I guess they are not actually from Francis Creek shale? I forgot to take pictures, but would be curious to hear from people familiar with this.

 

 

And of course, here are a few dinosaur eggs (the right type of rock) in situ

 

 

Here is the total haul. Probably not a lot for this site, but this is definitely the most productive pit 11 trip I’ve had so far.

 

 

Even better, unlike my previous visits, this time I found quite a few fossils in already open concretions.

 

Here is a shrimp molt

 

 

Both halves of a Calamites 

 

 

I think this is a Cyperites leaf

 

 

These two halves of Annularia whorls cracked on the drive home

 

 

And, of course, a neat anemone - Essexella ascherae. Surprisingly, this is the only one we found (so far).

 

 

Will keep this thread updated with new fossils as I freeze-thaw the remaining concretions. I will also be back to Mazonia this weekend, but will probably go to a different site.

 

I’m hoping this will become a mega-thread of all of my future Mazon creek trips. Out of all of the fossil sites I ever collected at, this is genuinely one of my favorites, if not the favorite - amazing fossils you can’t find anywhere else, plus instant gratification from finding concretions is always followed by delayed gratification over months of opening them. Here are my past trips to Mazonia and Braceville in 2023: 

[Mark Kmiecik]

14 hours ago, Anomotodon said:

I will also be back to Mazonia this weekend, but will probably go to a different site.

 

If you're heading south of the road at pit 11, remember that if you're not doing a belly-crawl to pick up the concretion, you're not it deep enough to get the good stuff.

[Anomotodon]

5 hours ago, Mark Kmiecik said:

 

If you're heading south of the road at pit 11, remember that if you're not doing a belly-crawl to pick up the concretion, you're not it deep enough to get the good stuff.

That’s the plan! I have already been to the Tipple hill area on the west side of Mazonia and bushwhacked through the forest on the east side, so Monster/Ponderosa lake area in the south is next.

[Anomotodon]

Went back to Mazonia yesterday with some friends, and this time decided to explore different areas to the south of the park. First, we parked near Ponderosa lake and followed the trail east around the lake.

 

 

Hills on the side of the trail contained abundant concretions. But we did have to crawl through endless branches and twigs - to illustrate @Mark Kmiecik advice, here is what it looked like.

 

 

And it was totally worth it:

 

 

Also, surprisingly, gravel in the parking lot had lots of complete concretions as well, we found about 20-30 (mostly small though). They were evenly distributed - so I don’t think they were leftovers from another fossil hunter, at least not recently.

 

 
 

Then we went on a hill next to Monster lake. Getting up there was quite a struggle, as it rained in the morning and the ground was extremely muddy. But despite everything, we did end up finding a lot of concretions there too.

 

Unfortunately, at both sites everything was covered in mud, so it was very difficult to tell if any of the already open concretions had fossils in them.

 

Here is a concretion that noticeably contained a twig.

 

 

A big Essexella:

 

 

I also found this possible sea cucumber, Achistrum sp. (or maybe a coprolite?) open on the Monster lake hill.

 

 

and cleaned:

 

 
 

Here are all of my concretions - probably about 100 complete ones I’ll freeze-thaw, my friends found about the same amount too. Concretions on the left are from around Ponderosa lake, on the right from Monster. That big one on the right I’m pretty sure will reveal an Essexella.

 

[deutscheben]

Thanks for sharing, it's always great to see Pit 11 reports from other folks. I have had very little success at the Tipple myself, but I know other people have been able to find some decent concretions there. I am hoping to get out to the park at least once more this spring, before things become overgrown and tick-infested. 

[Mark Kmiecik]

Nice haul. I never did well in that area because I had spots on private property to check in the spring and by the time I got around to looking there it had been picked over for the season. I never got far enough back into the Monster/Ponderosa area as I would start out with the tipple area. There's a rectangular depression on the right hand side of the path as you walk toward the tipple area about 150' x 75' and about 100' off the path where I would find tons of large Essexella each trip.

[Yoda]

@Anomotodon

Looks like you had 2 fantastic trips.

Hopefully those concretions will open up to be something really unusual. 

[Anomotodon]

23 hours ago, deutscheben said:

Thanks for sharing, it's always great to see Pit 11 reports from other folks. I have had very little success at the Tipple myself, but I know other people have been able to find some decent concretions there. I am hoping to get out to the park at least once more this spring, before things become overgrown and tick-infested. 

 

22 hours ago, Mark Kmiecik said:

Nice haul. I never did well in that area because I had spots on private property to check in the spring and by the time I got around to looking there it had been picked over for the season. I never got far enough back into the Monster/Ponderosa area as I would start out with the tipple area. There's a rectangular depression on the right hand side of the path as you walk toward the tipple area about 150' x 75' and about 100' off the path where I would find tons of large Essexella each trip.

 

9 hours ago, Yoda said:

@Anomotodon

Looks like you had 2 fantastic trips.

Hopefully those concretions will open up to be something really unusual. 

 

Thanks everyone! So far I’ve only been to Mazonia 4 times (and twice to Braceville), it’s quite a long drive from Wisconsin and I don’t have a car myself…

 

I’m trying to keep fossils from all of the locations within Mazonia separate, to see if there are any major differences between fauna/flora, I wonder if anyone tried to quantify that before? Just superficially, it seems to me that the Tipple area has a lower frequency of duds, albeit it’s more difficult to find a lot of concretions there. Both of the times I’ve been there I found interesting things. Meanwhile, in the more eastern sites where concretions are typically more dark-red, much more of them were empty or had lots of pyrite inside (although I still found nice fossils there too). Hills around Ponderosa seemed to have similar concretions - will take me a month or two to open most of them and find out.

Edited April 2 by Anomotodon

[connorp]

In my experience, the Ponderosa trail produces a lot of concretions, but they have a very low yield rate. Mostly pyrite.

The concretion with the desiccation cracks could be a cucumber but also could just be junk. If it is a cucumber, you'll be able to J-shaped sclerites under magnification.

[kurtdog]

Really love seeing those shots of Pit 11 as it presently lays. We did it in the 1960s when there was far less vegetation and growth on the hills. Got some really great flora out of there on those trips and an insect or two, maybe some worms, it's hard to recall, exactly, right now. We just cracked them open right there on the spot, didn't know any better, really. Pretty much all opened well, from what I recall, you just had to know where to tap them. You literally walked right over them, even climbing up the hills. Remember too we got boxes of pamphlets and books and maps and such from the Illinois State Geological Survey, the documentation free or just pennies, then, and I still got my stash. Keep up the good work, everybody, and thanks for sharing. Brings back some truly great memories for this crusty old ironstone concretion.

Edited April 7 by kurtdog

[Anomotodon]

On 4/4/2024 at 9:39 PM, connorp said:

In my experience, the Ponderosa trail produces a lot of concretions, but they have a very low yield rate. Mostly pyrite.

The concretion with the desiccation cracks could be a cucumber but also could just be junk. If it is a cucumber, you'll be able to J-shaped sclerites under magnification.

So far my luck with Ponderosa concretions is also low, just Essexellas, a very sad Neuropteris pinnule and a maybe-Tully/maybe-Essexella (posted it in the ID forum) . Even the nicely-shaped concretions from there seem to be somewhat “grainy” (tiny quartz crystals I think?) and very dark-red - and mostly void of fossils.

 

As for the potential Achistrum, I can’t see any sclerites but I think I found a mouth ring hidden under remaining calcite:

 

 
 

On 4/7/2024 at 10:41 AM, kurtdog said:

Really love seeing those shots of Pit 11 as it presently lays. We did it in the 1960s when there was far less vegetation and growth on the hills. Got some really great flora out of there on those trips and an insect or two, maybe some worms, it's hard to recall, exactly, right now. We just cracked them open right there on the spot, didn't know any better, really. Pretty much all opened well, from what I recall, you just had to know where to tap them. You literally walked right over them, even climbing up the hills. Remember too we got boxes of pamphlets and books and maps and such from the Illinois State Geological Survey, the documentation free or just pennies, then, and I still got my stash. Keep up the good work, everybody, and thanks for sharing. Brings back some truly great memories for this crusty old ironstone concretion.

 

Thanks, happy to bring back great memories  It sounds like it was a great time back then when you could find concretions everywhere. I think the sense of adventure of going up the hills and crawling through the bushes still makes trips to pit 11 very exciting and memorable!

[Anomotodon]

Visited Pit 11 again this weekend. We went to the north of the park, around Braidwood lake. First we checked the hills next to the main trail around the lake, but there was so much foliage that concretion-hunting was very unproductive.
 

 

However, right next to the cooling lake itself we found quite a few spots with complete concretions.

 

 
 

My friends also managed to fish out some very nicely shaped concretions from the edge of the lake itself. 
 

 

There was also this guy watching us. Perhaps his older relative is lurking somewhere in my bucket…

 

Overall, we found quite a few rocks to crack over the coming weeks. Not a lot of open fossils again - just a few miscellaneous plant bits. The concretions in this area seemed very different from the other pit 11 sites I visited - they are dark red, but “smooth” in texture and have few quartz inclusions, unlike the concretions from Ponderosa area. A lot of them are also very fragile, possibly because there is lots of water in that area year round.

 

Here are the first two fossils to open from this trip. This one I’m pretty sure is a coprolite from some herbivore (perhaps Arthropleura?), there are some plant-like inclusions.

 

Not entirely sure on this one - my guess is that it is also a coprolite, but I would appreciate any feedback. There are definitely plant pieces in the concretion, but that long white thing with a spot seems like it might be fauna?
 

Edited April 10 by Anomotodon