My 1St Mystery

[Roadrunner]

I e-mailed these pictures to a geologist I know and at first she thought the stridations on this boulder might be from erosion. But as you will see in one of the pictures I post - the lines are running in opposite directions in areas that are concave.

The striations "wrap around" this boulder - so although it looks like seashell-type marks, the shells would have had to have been huge as they go completely around the boulder (though admittedly, I couldn't check underneath it).

The area is in New Mexico in the Santa Fe Group, Miocene Epoch (7-25 million years ago), with some pliocene patches, but is known to have had boulders wash down from the nearby Sandia Mountains, which go back to the proterozoic period. This area is at the northern end of the Sandia Mountains in the foothills. "Fossils of marine life such as brachiopods, crinoids, fusilinids and corals are evident in some of these boulders."

All the fossils I have been able to identify in this general area have been sea life fossils, such as columnal crinoids, brachiopods, fusilinids, possibly an ammonite, and some possible worms.

Click to make larger...





The watch face is hazy with a worn bezel because it is scratched from carrying rocks (I wear it inside my wrist) - and I use a newer one for scuba diving (one that I can see ).

This photo shows one side that is flattened with shell-like striations - but it is the only flat area;




After going back and taking more photos, I think I found the striations cannot be due to erosion, because in this concave area they actually go in diametrically opposite directions.




Anyone have any better ideas about this boulder?

I have more pictures I can post if it might help.

Edited July 20, 2014 by Roadrunner

[Roadrunner]

Wow - not one answer.

Either this is really boring, or no one else has any clue either.

I can always delete it if it is boring.

Edited July 16, 2012 by Roadrunner

[thanatocoenosis]

I know nothing of the geology of your area, and perhaps a little more about plant material, but it resembles plant material that I have pulled from some coal fields in Appalachia... except that material is carbonized.

[DeloiVarden]

Not really my area even if I had an area, but I would guess this boulder was rolled under a glacier. Just a guess though.

[thanatocoenosis]

It doesn't look like any slickensides or striations that I have ever seen. I doubt that it is glacial. Too, that area was restricted to mountain glaciation.

[Bullsnake]

I'll venture a guess also. Mineral 'coating'.

The striations, though, I don't know.

This outcrop with calcite coating is at least 5 feet tall!

P.S. I don't think anyone on here is bored. Just genuinely don't know, giving it thought, or studying (researching) to try to help.

It's a very interesting find. No need to delete!

[grandpa]

Formation age aside, what I'm seeing reminds me of rudist clam.

[Fossildude19]

Wow - not one answer.

Either this is really boring, or no one else has any clue either.

I can always delete it if it is boring.

Not boring!!!! And please do not delete your posts!

Some patience is required.

You have to give at least a day or two on any new posts,... as we have a rotation of people looking at the forum at any given time. Not everyone checks in everyday, and Sunday night is not always a busy time for the forum. Most people are getting ready to post their weekend finds, so they may not be checking ID posts yet.

Unfortunately, you cannot always get an immediate response, especially on mystery items. You have 101 views of this post as of this writing, and only 6 replies.

I agree with Bullsnake's reasoning here. People are looking, but some may fear to comment unless they are absolutely sure as to what they are seeing.

My first thought was some type of bivalve/rudist as well.

Looking forward to other's opinions.

Regards,

Edited July 16, 2012 by Fossildude19

[FossilDAWG]

The overall appearance of the rock reminds me of the chert nodules that occur commonly in the Pennsylvannian and Permian limestones in that area. I recall reading in the "Paleontology of New Mexico" (by Barry Kues) that a very large productid brachiopod occurs in those rocks, and it seems to me your fossil (I do think it's a fossil) would be consistant with a large productid. When I get home tonight I'll see if I can find the relevant comment in Kues' book.

By the way, it seems a bit over-anxious to expect someone to post an ID withing two hours of your first post. You have to consider that 8:15 PM your time is 11:15 PM on the East Coast, and the middle of the night in Europe. I personally spend too much time on this site, but it's doubtful that I (or many others) would be online at 11:15 PM, would see your post (out of all the things that are posted on the forum every day), and would immediately reply.

Don

[Roadrunner]

OK - I won't delete it. I guess I got the wrong impression because someone posting after this post was getting huge replies. Maybe they just had something more fun to look at. But I really don't want to bore you, either.

I do know it takes a while to consider and figure things out, and I highly appreciate all the input and ideas you've all given me thus far, and if there are any tests I can run more on it in the field I'd be happy to try that. It also helps me learn and I'm now carrying a small plastic ruler with centimeters and inches for scale reference, since I noted some people do not like our using coins. If I don't have anything else to use, I'll put a pencil by something for picture scaling.

The boulder does seem to be "coated" as it has a layer about 1/4 to 1/2 inch thick, and that is where the stridations occur. I've looked for pieces that may have fallen off naturally as it is obvious that has happened, but I've found nothing in the immediate vicinity or below the boulder.

Here is as you start to look under the boulder;

Edited July 16, 2012 by Roadrunner

[Roadrunner]

The overall appearance of the rock reminds me of the chert nodules that occur commonly in the Pennsylvannian and Permian limestones in that area. I recall reading in the "Paleontology of New Mexico" (by Barry Kues) that a very large productid brachiopod occurs in those rocks, and it seems to me your fossil (I do think it's a fossil) would be consistant with a large productid. When I get home tonight I'll see if I can find the relevant comment in Kues' book.

By the way, it seems a bit over-anxious to expect someone to post an ID withing two hours of your first post. You have to consider that 8:15 PM your time is 11:15 PM on the East Coast, and the middle of the night in Europe. I personally spend too much time on this site, but it's doubtful that I (or many others) would be online at 11:15 PM, would see your post (out of all the things that are posted on the forum every day), and would immediately reply.

Don

Thank you for looking that up Don. Please read my post above regarding the reason you perceived me as "over anxious," and sorry I gave that impression.

The area in which I hike most has some pretty complex geological features, and is quite "colorful" while looking at maps that identify and date the minerals and terrain. I have found some fist-sized chert nodules, which was one of those things that somewhat surprised the geologist as she thought there wasn't much if any chert in this area. But I've found it in just about every color.

I discovered this boulder earlier in the year and though I've found other definitively organic fossils that I have yet to identify, this boulder has for some reason perplexed me the most.

Edited July 16, 2012 by Roadrunner

[Roadrunner]

Here are a couple more pictures;

One for scale and shape;

and another close-up on the other side.

Edited July 16, 2012 by Roadrunner

[Fossildude19]

OK - I won't delete it. I guess I got the wrong impression because someone posting after this post was getting huge replies. Maybe they just had something more fun to look at. But I really don't want to bore you, either.

Roadrunner,

No harm no foul!

It could be that the other ID post was more easily recognizable to those who happened to be online.

Not a matter of boredom, in any case.

I know that many here, myself included, tend to be a bit more reserved about offering opinions when faced with something from out of our area of expertise.

Just keep in mind, some "mysteries" are more,... um.... mysterious than others, ...and may take us a bit longer to figure out.

Regards,

Edited July 16, 2012 by Fossildude19

[Auspex]

As mysteries go, this one's a regular Agatha Christie!

I have no idea what, object or force, can account completely for what I am seeing.

[Roadrunner]

As mysteries go, this one's a regular Agatha Christie!

I have no idea what, object or force, can account completely for what I am seeing.

Thanks' for telling me that - it is more helpful than you know. I've got some other finds you all will probably be able to identify in less than a heartbeat that I'm stll trying to classify. I'll save those for another thread.

Here is a picture of the side where there is the concave area with the striations inside. You can see the flattened area just above that (to the left).

Thumbnail Picture Below;

Edited July 16, 2012 by Roadrunner

[Roadrunner]

One more close-up.

[Missourian]

Are there any visible fossils in the boulder? That is, besides the organic-looking striations....

[Roadrunner]

Are there any visible fossils in the boulder? That is, besides the organic-looking striations....

...not that I've been able to make out. Next time I'll take a magnifying glass with me and try to take a longer look for that.

In the photos I do keep noticing those "holes" in the areas of striation, however. And I remember running my finger over the hole in the flattened area, but didn't look well into it. Maybe I should take a flashlight too.

I don't know if the holes would help explain some of the circular areas that don't necessarily look organic that can be seen over other areas of the rock.

Edited July 16, 2012 by Roadrunner

[Herb]

The striations seem to curve and wave around the specimen. Most (not all) brachiopods and pelecypods have radiating and/or concentric features. I will stick out my neck and say geological in origin. I've seen something like it but can't remember where. I will be happy to be proved wrong if it is a fossil, it is a really neat specimen of something.

[Roadrunner]

The striations seem to curve and wave around the specimen. Most (not all) brachiopods and pelecypods have radiating and/or concentric features. I will stick out my neck and say geological in origin. I've seen something like it but can't remember where. I will be happy to be proved wrong if it is a fossil, it is a really neat specimen of something.

Thanks!

The only area where it seems like it might be "radiating" is the flattened area. I know it is hard to see in the pictures. Here is one that is a little closer, and I'm going to have to check that incomplete rectangular area I now see to the left of the hole (after the flat area). That looks a bit like it might be a trace fossil of a crinoid stem - which I get a LOT of around there.

Edited July 17, 2012 by Roadrunner

[Missourian]

Some of the striations appear to bifurcate. Here is my interpretation of what I see :

[Roadrunner]

Some of the striations appear to bifurcate. Here is my interpretation of what I see :

That is a good observation, and thank you for accentuating and noting that.

[Roadrunner]

So the "bifurcation" would seem to make it organic, right Missourian?

What software do you use to help you enhance these photos? That is a great bit of software to have!

Edited July 17, 2012 by Roadrunner

[Roadrunner]

The striations seem to curve and wave around the specimen. Most (not all) brachiopods and pelecypods have radiating and/or concentric features. I will stick out my neck and say geological in origin. I've seen something like it but can't remember where. I will be happy to be proved wrong if it is a fossil, it is a really neat specimen of something.

I wish you could remember what you've seen like it before.....most people are saying the opposite, that they haven't seen anything like it. But - that is the way it goes sometimes

Do the seemingly bifurcated striations sway you at all toward organic? I've looked up rudisk clams. The only artist renditions of them are the circular ones that I've found. Some materials do mention other irregular shapped masses - but I've not found how any of those might have looked.

Edited July 17, 2012 by Roadrunner

[ashcraft]

I am thinking clam also, but I think you are looking at the wrong scale. Think giant clams, measuring in feet.

Brent Ashcraft