Jump to content

Mazon trip Nov 14, 2021


toddf74

Recommended Posts

Hello fossil hunters! I am asking for some help as a humble beginner. 

 

Yesterday I went out with my son (age 14) to a site just south of Braidwood, IL. We were collecting near Ponderosa Lake, to be more precise. This is our second trip out there. The first time we really had no idea what we were looking for, but now we are getting a little more experienced after reading a lot and digging around. In total we found around 60 intact (good shape, in my unprofessional view) concretions, as well as some interesting fragments. We had a nice time collecting yesterday in the cold. We were the only people out there. Maybe we are crazy! 

 

I am requesting help with an identification, and some general advice on how to best tackle opening the pile of concretions we found. 

 

First, this was one found awhile back and I believe it is similar to a find that connorp found: Macroneuropteris pinnule (see thread below)

 

 

Secondly, we found some concretions that were already open. I just grabbed a few to have here since I have read that sometimes they contain jellyfish. I cannot determine anything by looking at these. Does anyone have an opinion on these? The coin is about 20mm in diameter for reference. 

 

Finally, I have read about the freeze/thaw method as well as using a hammer to crack them open. I will start out using the freeze thaw method. I separated them into groups of concretions that I though were good. The picture below shows them laid out on some paper towels in the kitchen. I just washed them off and am waiting to start the opening process. 


I have a few questions around both methods: 

Freeze/Thaw

1. I am going to keep them outside in a bucket in water for 20 days. Then I will start freezing them. How long do I need to keep them in the freezer? Also, once I take them out, do I just run hot water on them, or do I let it thaw in room temperature? Once I have determined if any have opened, do I need to re-soak the concretions again? or, just straight back in the freezer?

 

Hammer

2. Does anyone have a good video of how to use a hammer on these things? I tried it on a few I had before and it was a disaster. I might be using the wrong hammer. I might need a chisel, too? I might not be hitting in the correct spot? This might seem basic to you pros, but I am really an amateur. 

 

IMG-4138.JPG

IMG-4254.JPG

IMG-4249.JPG

  • Enjoyed 1
Link to comment
Share on other sites

Hi @toddf74, glad to hear you’re getting interested into Mazon creek fossils. Let me start by saying that the Mazonia wildlife area is currently closed for fossil hunting at the moment from October for February for hunting season! I suggest you wait until March to get out again. Also, you need to fill out a permit for when you go in case you haven’t done this before.

 

Now for your other questions, to open them, soak them in water. I usually soak them for a week. You keep them frozen until the entire bucket/container is frozen through. I’ve never experienced any additional luck by having them stay frozen longer but perhaps others will have suggestions. Once they’re thawed out, I like to take them out of water and let them dry. 
 

For your pieces with white stains on them, these are covered in calcite. You can get white vinegar and soak them in that and it should dissolve the calcite. I also dilute the calcite so it’s not quite as concentrated.

  • I found this Informative 1
Link to comment
Share on other sites

First, let me say "nice haul", especially for that area.

 

The first photo is a basal pinnule of Macroneuropteris scheuchzerei, most probably. Google "macroneuropteris" and go to the Wikipedia listing -- see the first photo. The ones with the nickel next to them are halves that have weathered for quite some time. Wherever you see those you'll usually find unopened concretions as well, because if those have been there long enough to weather like that it means no one else has looked there for quite some time. You can soak those in some vinegar to see if they'll clean up at all. Most of the time you'll get nothing, but even if you do it will be barely distinguishable.

 

Put your hammer away for now. Forget about the chisel completely. Put the concretions in a bucket of water and let them soak for a couple of weeks to make sure they are soaked ALL the way through. Then put them into smaller containers of water that will fit in your freezer. (Hint, smaller containers freeze faster and thaw faster than larger ones.) As soon as they freeze you can thaw them. If you want to hurry them up use cold or lukewarm water. You're not trying to blow them up -- when the water froze it expanded and did all the work it could in one cycle. You can inspect each concretion each time they thaw for obvious cracks, or hairline cracks that go all or most of the way around the edge. Those can be set aside to dry for a couple of days. The rest go back in the fridge for another freeze/thaw cycle. I would usually check for signs of cracking every two to five cycles, depending on the location where they were found. In a day or two, once the cracked ones are more or less "dry" you can tap around the edge on the crack as you hold the concretion in your hand. This will prevent smacking it too hard. Once you've gained experience with different types from different locations you'll develop a knack for how much force is necessary. What you need to know now is that patience is your best friend and you'll get the best results usually by letting the freezing water do the cracking. My best specimens never came close to a hammer. The nodules found around Ponderosa will require more than the average number of cycles before cracking open. That's the nature of the beast. Nodules from other areas, I've had all pop open in five cycles or less. Some I have are still not open and have been through more than 75 cycles.

 

Patience will yield the best results. I know I already mentioned that, but it bears repetition. Good Luck.

 

P.S. -- The ones with the cracks that you dried, but refused to crack open yet, you'll need to soak again for at least a couple of days before continuing freeze/thaw.

Edited by Mark Kmiecik
typo/punctuation/grammar
  • I found this Informative 2
  • Enjoyed 1

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

Link to comment
Share on other sites

57 minutes ago, Runner64 said:

Let me start by saying that the Mazonia wildlife area is currently closed for fossil hunting at the moment from October for February for hunting season!

I would like to emphasize this. The OP was fortunate that nothing bad happened. The fossil hunting dates are clearly marked at multiple points in the South Unit.

  • I found this Informative 1
  • I Agree 1
Link to comment
Share on other sites

11 minutes ago, connorp said:

I would like to emphasize this. The OP was fortunate that nothing bad happened. The fossil hunting dates are clearly marked at multiple points in the South Unit.

Thank you, we will not be going back there again unless it is allowed. 

  • Enjoyed 1
Link to comment
Share on other sites

Mark and Runner64, thank you for the great tips on the next steps! I will work on it this winter and re-post once we find something. I am sure there will at least be 1 in that lot!!!! Cheers

Link to comment
Share on other sites

On 11/15/2021 at 6:34 PM, toddf74 said:

Mark and Runner64, thank you for the great tips on the next steps! I will work on it this winter and re-post once we find something. I am sure there will at least be 1 in that lot!!!! Cheers

Those are some good-looking nodules. You should do quite a bit better than just finding one.

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

Link to comment
Share on other sites

  • 3 weeks later...

Quick update: I have been freeze/thawing some of the nodules I found awhile back. I was wondering if this was something. I thought maybe it could be Essexella or another type of jellyfish. Any ideas? It might also just be nothing (I am anxious to find something!) 

259385074_image_123927839(1).JPG

image_123927839.JPG

Link to comment
Share on other sites

15 minutes ago, toddf74 said:

Quick update: I have been freeze/thawing some of the nodules I found awhile back. I was wondering if this was something. I thought maybe it could be Essexella or another type of jellyfish. Any ideas? It might also just be nothing (I am anxious to find something!) 

259385074_image_123927839(1).JPG

image_123927839.JPG

This looks might be one but may also be suggestive fracture lines

Link to comment
Share on other sites

57 minutes ago, Runner64 said:

This looks might be one but may also be suggestive fracture lines

It is difficult for me to tell. this is the first one that opened that looked like it could be something, though. So I was optimistic. 

Link to comment
Share on other sites

Here are 2 more that I just opened. The first one (first 2 images) seems to have some lines that indicate something but I have no idea. The second one maybe another jellyfish?

image_123927839 (4).JPG

image_123927839 (3).JPG

image_123927839 (2).JPG

Link to comment
Share on other sites

The one you posted on Monday is Essexella asherae, a jellyfish. The last one may be one also, but the preservation is very poor. The one in between is a shrimp, possibly Acanthotelson stipmpsoni, (google it and look at images) but again, the preservation is not as good as we would like, and it would help if you took additional photos with the light source coming from different angles and points of the compass to increase the visibilty of the bas relief. I'm not really sure on what I think is the shrimp, so wait for others to chime in with their takes on what it is.

 

 

 

jelly.jpg   jelly2.jpg.c057ca0f370f41ef49d6fead922eb70e.jpg

Edited by Mark Kmiecik
additional info
  • Thank You 1

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

Link to comment
Share on other sites

I cracked another one open tonight (I glued it back together).

 

It appears to be a big white spot in the middle, but I have no idea if this is actually anything. I have not seen any other samples like this before, except one for sale on online (it was unidentified). 

390675837_image_123927839(6).JPG

2092396721_image_123927839(5).JPG

Link to comment
Share on other sites

Looks like this one is a "dud", but don't dump it until others chime in, or preferably, an experienced collector sees it in person. I can't tell if that's something along the cracks or not.

  • I found this Informative 1

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

Link to comment
Share on other sites

11 hours ago, Mark Kmiecik said:

Looks like this one is a "dud", but don't dump it until others chime in, or preferably, an experienced collector sees it in person. I can't tell if that's something along the cracks or not.

I think it is a dud. The darker parts around the cracks are from the super glue. 

 

So, it looks like people are selling duds on online!!!!! for a mere $10! 

Link to comment
Share on other sites

Yes, I would agree from the picture that this one is just mineralization. Interpreting Mazon concretions can be quite difficult, though, so as @Mark Kmiecik said, having someone with expertise view it in person is the best bet to know for sure whether or not there is a fossil there.

Link to comment
Share on other sites

On 12/8/2021 at 12:24 PM, toddf74 said:

Here are 2 more that I just opened. The first one (first 2 images) seems to have some lines that indicate something but I have no idea. The second one maybe another jellyfish?

image_123927839 (4).JPG

image_123927839 (3).JPG

image_123927839 (2).JPG

 

As Mark said, this si a shrimp. I wonder if itmight be a stomatopod such as Tyrannophontes rather than Acanthotelson, though.

  • Thank You 1
Link to comment
Share on other sites

If those "spikey" looking bits at the posterior end are parts of the telson it makes me lean towards Acanthotelson. @deutscheben @Nimravis What do you think this shrimp is?

  • Thank You 1

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

Link to comment
Share on other sites

Here's my read on it:

 

image.png.c786bf50b994937fe7ece7efd1987335.png

 

The pleura sweep a little backwards on the ventral edge, which is why I'm interpreting the top as anterior and the bottom as posterior. The posterior expansion is consistent with stomatopods hence why I think this might be Tyrannophontes. But, I'm not an arthropod expert so I could be wrong.

  • Thank You 1
Link to comment
Share on other sites

Found something interesting last night. To me it looks like an impression of a leaf of some sort. Half of the concretion was already broken off, so this is all I had. 

pics 2.jpg

520226934_image_123927839(7).JPG

  • Enjoyed 1
Link to comment
Share on other sites

Jellyfish is my first impression, but let's wait for others to chime in. 

  • I found this Informative 1
  • Thank You 1

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

Link to comment
Share on other sites

1 minute ago, Mark Kmiecik said:

Jellyfish is my first impression, but let's wait for others to chime in. 

I think you are right Mark, I would say Jellyfish as well.

 

Rock On !!

Phil

  • Thank You 1
Link to comment
Share on other sites

5 minutes ago, flipper559 said:

I think you are right Mark, I would say Jellyfish as well.

 

Rock On !!

Phil

That is cool!!! thanks guys. My son really liked this one!!!!

  • Enjoyed 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...