Mazon Creek Nodules: Did I Do Something Wrong?

[paleoflor]

Hi all,

A couple of months ago, I acquired a small box of unopened Mazon Creek nodules via the forum. After reading whatever I could find on the freeze-thaw method (too many TFF topics to cite here), I started doing the following. First, I submerged the nodules in water (in 6 cm deep trays, fully submerging the nodules, which were placed next to each other, not stacking them) for one week (I was on vacation). Subsequently, I put the trays in freezer until frozen solid (1 day). I repeated these steps (duration 1 day each) until nodules popped open/could be opened by hand. Most of my nodules have opened by now (two to go still) and this is what I found:

Some of the nodules seem to contain bits (e.g. the ones on lower right - any ID suggestions?), but most are empty, at least to my untrained eye (have zero previous experience with Mazon Creek material). I've read the "content" of the nodules varies from site to site, and general estimates range from 1/4 to 1/10 nodules yielding something fossiliferous. However, most others who obtained nodules from the same source reported nice finds in their batches. Given this, I was wondering whether I did something wrong method-wise. Also, is it worthwhile to re-split nodules, i.e. put them back in the freezer and try splitting them along a parallel plane?

P.S. During the freeze-thaw cycling, many of the nodules started to "peel"; the outer parts started to disintegrate in somewhat onion-like fashion. Is this normal?

Thanks for your input,

Tim

[Stocksdale]

That's the way I do it. I also end up with a whole lot that have nothing that I can decipher.

I think the 1/4 ratio is not even close to reality. I would think the 1/10 ratio may be too optimistic for most sites. Here's a quote from George Langford's journal: "We gathered and cracked open from 2,000 to 3,000 nodules each day, securing there from 150 to 250 specimens daily." That would be a bit less than the 1/10 ratio.

I would be curious from others about success of re-splits.

[paleoflor]

Thanks for confirming I didn't screw things up, for that would have been a bummer. I had loads of fun putting trays of nodules in and out of the freezer, and especially with explaining to others why I did this. All together this has been quite a fun experience (the method is so grossly different from what you do in "normal" carboniferous rocks!). Will try to re-split some of them - can't do any harm, I guess. If I find anything this way, I'll surely report here.

Cheers,

Tim

[RCFossils]

Hi Tim,

You are doing everything correctly. As you are already aware, only a small percentage of concretion will contain a recognizable fossil. The site where the concretions were collected along with the shape will adjust the percentage higher or lower.

There are certain areas where concretions are abundant (one could collect thousands in a day) but less then one percent will contain anything. There are other sites where your odds would be over fifty percent.

I am not a big fan of purchasing unopened concretions as there is a lot of low quality material (usually sold on Ebay) that I can tell by the shapes will not contain anything. The listings usually state that the seller has found very rare fossils such as fish and insects at the area the concretions were collected.

Having said that, I understand that for some it is less about what you find and more about acquiring fossils from a site that you might not be able to collect.

Your concretions appear to all have been collected from the Essex portion of the deposit. I have found that around ten percent of concretions from around Pit 11 will contain a fossil. The majority will be the common jellyfish Essexella asherae.

Your fossil on the bottom right is a decent example of this jellyfish. I think I see at least one other in your grouping. Since jellyfish are soft bodied, the preservation can vary greatly. Some are just preserved as a color difference in the rock. Others (like your specimen) can be quite three dimensional. For the amount of concretions you started with, you are right where I would expect you to be.

Remember the more concretions, the higher your odds of finding something good. I collect between three and five thousand well shaped concretions a year from good locations. I am lucky to get a few nice specimens.

Good luck!

[Stocksdale]

As was just mentioned, there are two biotas--one more marine (essex) and one more terrestrial (braidwood)--within a few kilometers in the Mazon Creek area. The strip mine area in the south that is more marine is now a State Park and is where most people collect and likely where your nodules came from. And then, there is a slightly older strip mine in the north that is terrestrial, but is unfortunately mostly private property. In between these areas, there are even older underground coal mines from the late 1800s and early 1900s. Each of these mines have spoil piles that contain nodules. I've collected from one of these that was mostly terrestrial.

I'm pretty new to this, but from my brief experience, the terrestrial area has a little better ratio and fewer "blanks." Or maybe they are just more recognizable to me since they are plants. In the spring, I could probably get some nodules from the terrestrial area and send them to you.

[Ramo]

I too had trouble finding a precise method for "freeze/thaw". I just started trying to open the ones I collected last year. I just grabbed a few and put them in a container with water over them and then froze them. I got a lot of the layers off as well, and most I've opened so far are splitting all over the place, not into nice even halves. Do I need to soak them longer before freezing them. I've only done 5-6 so far as an experiment to see how it works. So far, so bad I guess. I expected nice splits down the middle, but mine seem to just be more or less shattered.

[RCFossils]

I too had trouble finding a precise method for "freeze/thaw". I just started trying to open the ones I collected last year. I just grabbed a few and put them in a container with water over them and then froze them. I got a lot of the layers off as well, and most I've opened so far are splitting all over the place, not into nice even halves. Do I need to soak them longer before freezing them. I've only done 5-6 so far as an experiment to see how it works. So far, so bad I guess. I expected nice splits down the middle, but mine seem to just be more or less shattered.

I usually soak my concretions for several days and then place them in my chest freezer. I will normally let them freeze for 2 days and then take them out and soak in hot water. If they do not open, I will place them right back in the freezer and repeat the process. Most will split between 5 and 15 cycles. It is normal to have sections flake off. The more you freeze thaw, the more will flake. It is not unusual to start with a nice shaped concretion and end up with something you would never collect in the field.

When the concretions start flaking it is also a sign that it is not likely there will be a fossil in the concretion. Most of the time the concretion will split along the plane of the fossil before it starts flaking.

[paleoflor]

[...] The majority will be the common jellyfish Essexella asherae. [...] Your fossil on the bottom right is a decent example of this jellyfish. I think I see at least one other in your grouping. Since jellyfish are soft bodied, the preservation can vary greatly. Some are just preserved as a color difference in the rock. Others (like your specimen) can be quite three dimensional. [...]

A jellyfish? OK, didn't see that coming, he-he. Thank you for the ID.

[...] I am not a big fan of purchasing unopened concretions as there is a lot of low quality material (usually sold on Ebay) that I can tell by the shapes will not contain anything. The listings usually state that the seller has found very rare fossils such as fish and insects at the area the concretions were collected. [...] Having said that, I understand that for some it is less about what you find and more about acquiring fossils from a site that you might not be able to collect. [...]

Oh but I didn't purchase the concretions with the expectation I would add gold to my collection. Mostly, I just wanted to experience how the freeze-thaw method works. I do have a small Mazon Creek collection, obtained by trading already-opened nodules.

As was just mentioned, there are two biotas--one more marine (essex) and one more terrestrial (braidwood)--within a few kilometers in the Mazon Creek area. The strip mine area in the south that is more marine is now a State Park and is where most people collect and likely where your nodules came from. And then, there is a slightly older strip mine in the north that is terrestrial, but is unfortunately mostly private property. In between these areas, there are even older underground coal mines from the late 1800s and early 1900s. Each of these mines have spoil piles that contain nodules. I've collected from one of these that was mostly terrestrial.

I'm pretty new to this, but from my brief experience, the terrestrial area has a little better ratio and fewer "blanks." Or maybe they are just more recognizable to me since they are plants. In the spring, I could probably get some nodules from the terrestrial area and send them to you.

This explains a lot, a great lot. Can I assume all plants to be from the Braidwood biota? I previously obtained a modest collection of opened nodules, but the information I could get was rather limited (locality description just "Mazon Creek"). Clearly, I should have spent more time making myself familiar with the locality!

Cheers,

Tim

[Stocksdale]

One does find quite a lot of plant material in both areas. But it is more exclusively plants and more of them in the northern area. It is more of a gradation of marine to terrestrial.

Also the entire area was a coal forest (lycopod and psaronius) just prior to being inundated by marine intrusion. So the colchester coal is what the coal companies are trying to get to, but in the process they pile up the layer of rocks right above the coal seam which is where the Francis Creek Shale and the nodules are found.

Here's a map of the area that I've color coded for fun. The orange area is pit 11 where it is now a state park. The green area is the other strip mine pits (pits 1-8) with mostly terrestrial plants and animals. In between these areas are lots of mine symbols. Each of these is the location of an underground mine and there are usually spoil piles at those locations.

In one of the piles from an underground mine is where I found quite a lot of wood (trunk of a tree and other material) which I've asumed to be psaronius. It was mixed in with a bit of coal and francis creek shale. I assume this was at the top of the colchester seam as it was being covered in mud and leaf debris as the water rose.

Edited November 14, 2013 by Neophytus Elginian

[Stocksdale]

While I had it opened in photoshop I decided to add a layer from google earth. Also the actual Mazon Creek is shown in blue. Note that most of the sites are a bit away from the creek but people do find nodules in the creek as well.

Edited November 14, 2013 by Neophytus Elginian

[Wrangellian]

I'm having all the same problems with the batch I bought. Many splitting unevenly or splintering altogether, and of the ones that have opened so far I'm not sure I have anything. Unless I find something good in at least one of them I would say the cost of the batch plus shipping to Canada is not worth it... I suspect the remaining unopened ones don't have anything either if they have not split by now?

[Rob Russell]

Eric, you spent a total of $36. I hope it wasn't your last dollar.

[Wrangellian]

Eric, you spent a total of $36. I hope it wasn't your last dollar.

No, but close... Guess I was expecting more than I have seen so far, which is not even one for sure yet - Do the fossiliferous ones not open sooner than the non-? Most of the ones you sent are pretty small and most are splintering unevenly, which I get the impression means they likely won't have anything. I hope that's not correct..

Edited November 17, 2013 by Wrangellian

[MarcoSr]

Tim

Looking at your nodules in your picture it looks like you did a great job splitting them. I almost bought some just to see if I could split them.

I know everyone would like to find all kinds of rare fossils inside them or at least some nice common stuff. But you have to realize if you had a high probability of finding common stuff or even a rare fossil, the seller would be splitting them himself and selling the ones with the fossils for a lot more money. Take a chance and learn like you did. I would be very happy with the jellyfish.

Thanks for your post as now I know how to attempt to split these nodules.

Marco Sr.

[Wrangellian]

That's the conclusion I found myself heading towards but didn't want to jump to it.

Am still working on the last handful of stubborn, small ones....

[Rob Russell]

Tim

Looking at your nodules in your picture it looks like you did a great job splitting them. I almost bought some just to see if I could split them.

I know everyone would like to find all kinds of rare fossils inside them or at least some nice common stuff. But you have to realize if you had a high probability of finding common stuff or even a rare fossil, the seller would be splitting them himself and selling the ones with the fossils for a lot more money. Take a chance and learn like you did. I would be very happy with the jellyfish.

Thanks for your post as now I know how to attempt to split these nodules.

Marco Sr.

I do split my own nodules, and sell the fossils. Do your homework Marco.

[MarcoSr]

I do split my own nodules, and sell the fossils. Do your homework Marco.

I was trying to lower people's expectations. Why don't you chill out.

Marco Sr.

Edited November 19, 2013 by MarcoSr

[Auspex]

I hope, ardently, that no one has or is suggesting wrongdoing!

To me, the transactions appear to have been made in nothing other that good faith. In my experience, far more duds than not are the norm with nodules, even when selected with a trained eye.

[Wrangellian]

I feel like I am partly responsible for fanning these flames, but I don't think anyone was suggesting wrongdoing. But I did get the impression somehow that there was a better chance of getting something than there actually was. Either that or I'm just unlucky and I happened to get the one batch with nothing. I have never been lucky at gambling so I tend to refrain unless the chances are really good. Turns out even then I lose.. For me $36 is a bit much to pay for driveway fill, so I was thinking either the price should be reduced if the chances are less, or, if it can be determined just what the chances are of finding something, say 1 in 20? they should not be sold in less quantities than 30 - just to ensure that schmucks like me are not going to be skunked and raise a stink in TFF.

[Pagurus]

I suppose I should chime in since I also purchased a small batch of Rob's nodules. I've been reading about Mazon nodules for the last couple of years, since I joined the forum. While planning one of my fossil hunting vacations I tried to figure out how to drive all the way out to Illinois and back in the time I had, and to keep within my budget. It didn't make sense for me this year, though I'd love to collect there someday. When Rob offered to sell a few that he had collected, giving me the chance to open my own, I was excited. I had never had this experience before and was thankful I didn't have to spend all that money on gas, motels, and food, though of course it would have been a lot more fun to hunt for them myself. I thought Rob's prices were very reasonable; I would have paid more. I wanted to try my hand at opening these nodules and this was an inexpensive way to enjoy the experience. Of course there were no guarantees I would find anything at all. Of course if I hunted for them myself there would be no guarantees I would find anything at all. Rob sent them promptly and safely and I experimented with the freeze-thaw process when they arrived. It's been an informative and enjoyable experience. That's exactly what I wanted. If I wanted a worm or a shrimp or a jellyfish I would have ordered one. I wanted the experience, not necessarily the fossil. Part of the experience, of course, is the anticipation, and each time I opened the freezer and let the nodules melt I hoped to find a treasure. The money I spent, though, was for the experience, not the treasure. As it turned out, most of the nodules had nothing recognizable, but one did have what appears to be a jellyfish. Of course I was disappointed not to find more, but I certainly got more than my money's worth. Thank you Rob!

Mike

[MarcoSr]

I hope, ardently, that no one has or is suggesting wrongdoing!

To me, the transactions appear to have been made in nothing other that good faith. In my experience, far more duds than not are the norm with nodules, even when selected with a trained eye.

I didn't feel Rob did anything wrong. I still don't. But I think his reply to Wrangellian about his "last dollar" was totally inappropriate.

Marco Sr.

[Rob Russell]

I didn't feel Rob did anything wrong. I still don't. But I think his reply to Wrangellian about his "last dollar" was totally inappropriate.

Marco Sr.

Marco.

I haven't said anything inappropriate. You're not familiar with my business. The people involved in my business. The products I sell. The places I sell them, or anything. You and I have never interacted, ever. For you to try and "lower peoples expectations", or suggest that I'm selling snarge because if I wasn't id be opening them myself and selling them is not for you to assume, or suggest. You have nothing to base your opinions on. That's why you got the response from me that you did. Now, I'd be happy to sell you some nodules so you do.

[MarcoSr]

Marco.

I haven't said anything inappropriate. You're not familiar with my business. The people involved in my business. The products I sell. The places I sell them, or anything. You and I have never interacted, ever. For you to try and "lower peoples expectations", or suggest that I'm selling snarge because if I wasn't id be opening them myself and selling them is not for you to assume, or suggest. You have nothing to base your opinions on. That's why you got the response from me that you did. Now, I'd be happy to sell you some nodules so you do.

Good luck with your business.

Marco Sr.

[caldigger]

I was one of the first TFF patrons to jump on the band wagon and buy a group of nodules from Rob. I went into it with no true expectations, it was an experimental endeavor and I wanted to try and uncover something myself. I don't think his price was unfair in the least. He even gave me further instruction on the process of freeze/thaw method. I must say, the results had less than a "WOW" factor, but uncovering an unopened fossil nodule is a crapshoot in it's self. Not even he (Rob) can tell for sure if it would hold anything or not.

This whole transaction should have been entered with a wide-eyed sense of curiosity and not with expectations of trophy specimens. My results ended up with a big bowl of stone "cornflakes". However, I did end up with one that had a white smear, which I have learned is a jellyfish and one that has a bit of plant material the size of a grain of rice.

Once again, it was just a fun experiment to have the thrill of opening (or rather flaking) an unopened nodule for the first time. Ya, if every nodule were to contain prize winning fossils, he wouldn't be selling them for such a low price. I am not upset with the purchase at all.

Edited November 20, 2013 by caldigger

[Wrangellian]

I was never expecting any 'prize winning' fossils, but I was led to believe I'd find something, perhaps a jelly and a fern or two - at least that this would be more likely than not - so of course I would be disappointed if I found nothing, and so far, this has been the case. Maybe I should wait till these last few small ones are split but as I said before, I get the impression that the stubborn ones won't have anything, and since other buyers have had nothing in their batches this looks more likely.

I have no truck with anything Rob did or said, unless he does know more than he is letting on as to which ones will have something, but I am making no accusations, I really don't know. He has been helpful and pleasant during the whole transaction in PM conversation etc, I can say that much.

But for me, in retrospect, my budget is a bit too small to spend $36 for the experience of opening a bunch of duds. One fossil (however common) would have made the experience complete and worth the price, but so far I have not placed an opened nodule into my Mazon collection that I could say "I opened this one myself". So either I should have spend more on a larger package but with shipping to Canada that gets quickly prohibitive for me, or just not done it at all. I will definitely come back and change my tune if on the off-chance one of these remaining nodules has something!

Edited November 20, 2013 by Wrangellian