David Joyce Posted March 8, 2022 Share Posted March 8, 2022 This stone was found 40 years ago in the Santa Fe National Forest in New Mexico. I am trying to date the fossils. I guess it is Cretaceous but I am a newbie. Link to comment Share on other sites More sharing options...
Rockwood Posted March 8, 2022 Share Posted March 8, 2022 I don't think these are fossils. They look like clasts deposited in a relatively energetic depositional environment to me. 1 1 Link to comment Share on other sites More sharing options...
Wrangellian Posted March 8, 2022 Share Posted March 8, 2022 I see at least one sectioned bivalve. Maybe some icnhofossils but not sure what those other things are. I don't know the area but if you can find a decent geological map of the area where it was found you should be able to put an age on it. Link to comment Share on other sites More sharing options...
Rockwood Posted March 8, 2022 Share Posted March 8, 2022 1 hour ago, Wrangellian said: I see at least one sectioned bivalve. Maybe some icnhofossils Where ? Link to comment Share on other sites More sharing options...
Wrangellian Posted March 9, 2022 Share Posted March 9, 2022 (edited) 5 hours ago, Rockwood said: Where ? I believe the leaf-shaped thing inside the circular concretion is a bivalve. All the other blobs and circles and such, I'm not sure - could be concretionary or ichno or who knows? I'd like a closer look at those. Are the numerous small circles some kind of (modern) lichen? Edited March 9, 2022 by Wrangellian Link to comment Share on other sites More sharing options...
Rockwood Posted March 9, 2022 Share Posted March 9, 2022 5 hours ago, Wrangellian said: who knows? I suspect that professionals get used to believing they do after needing an answer to this question too much too many times. Just a word of caution. Link to comment Share on other sites More sharing options...
Wrangellian Posted March 9, 2022 Share Posted March 9, 2022 1 hour ago, Rockwood said: I suspect that professionals get used to believing they do after needing an answer to this question too much too many times. Just a word of caution. Not sure what you mean by that... 1 Link to comment Share on other sites More sharing options...
Rockwood Posted March 9, 2022 Share Posted March 9, 2022 Calling the shape a bivalve just causes me to imagine formal education requiring answers now. Time is money so fast is a prerequisite. The warning is to be aware of hidden influences that old habits could have. Link to comment Share on other sites More sharing options...
Wrangellian Posted March 9, 2022 Share Posted March 9, 2022 11 hours ago, Rockwood said: Calling the shape a bivalve just causes me to imagine formal education requiring answers now. Time is money so fast is a prerequisite. The warning is to be aware of hidden influences that old habits could have. I'm still not sure what you mean. Is this a roundabout way of saying you doubt my suggested ID? 1 Link to comment Share on other sites More sharing options...
Wrangellian Posted March 10, 2022 Share Posted March 10, 2022 (edited) To illustrate what I suggested above, here is a fossiliferous concretion I found at my local Cretaceous site. This one is an ammonite (and some other bits of wood and whatnot) instead of a bivalve but you get the idea. Edited March 10, 2022 by Wrangellian Link to comment Share on other sites More sharing options...
Rockwood Posted March 10, 2022 Share Posted March 10, 2022 Frankly I don't see a good comparison in the amount of information available. This shows texture, contour, and relative positioning. The post has none of this that I see as being unquestionable. Link to comment Share on other sites More sharing options...
BobWill Posted March 10, 2022 Share Posted March 10, 2022 I am wondering why you think the area where you found it is Cretaceous. As Wrangellian said you can find the name of the formation on a geological map and then search for information on that for the age of any find. I would also like to know why you think there are fossils there. The shapes in the surface could well be something but the photos do not validate that without more evidence. Do you find other fossils there that are more plainly visible? 1 Link to comment Share on other sites More sharing options...
ClearLake Posted March 10, 2022 Share Posted March 10, 2022 I think if you want to date the rock, you better do it with a map as suggested. If any of those are fossils, and I see a cross section that could possibly be one, they would have to be much more identifiable to date the the rock. Right now, it looks like very iffy fossils, more likely geologic and therefore I would look for other means of putting an age to it. Link to comment Share on other sites More sharing options...
Wrangellian Posted March 10, 2022 Share Posted March 10, 2022 (edited) Just to ensure we're all on the same page, this is the item I'm looking at. I'm not just tossing vague guesses out there... I'm not assuming the OP is correct about the age but it sure looks like the kind of lithology I see at my local Cretaceous site (shale with concretions) and this thing sure looks like a sectioned bivalve filled with a crystalline mineral. I've seen many similar examples. To be sure I would like to see some clearer/closer shots, but that first photo is better than a lot of snapshots that people have posted in the ID section and I've seen firmer IDs come from worse... Edited March 10, 2022 by Wrangellian sp. 1 1 Link to comment Share on other sites More sharing options...
Rockwood Posted March 11, 2022 Share Posted March 11, 2022 That's what I thought you were referring to. No, it doesn't seem at all clear to me that it is a shell. It could be, but the definition really just isn't good enough to say it is. 1 Link to comment Share on other sites More sharing options...
Wrangellian Posted March 11, 2022 Share Posted March 11, 2022 The definition of the photo or of the item itself? Link to comment Share on other sites More sharing options...
Rockwood Posted March 11, 2022 Share Posted March 11, 2022 The photo is a bit unclear when zoomed, but I think it shows enough definition to put a bivalve ID in serious doubt. The lines don't quite stay in line, and the texture seems wrong. Link to comment Share on other sites More sharing options...
Wrangellian Posted March 11, 2022 Share Posted March 11, 2022 (edited) OK. What I'm seeing is a x-sectioned bivalve filled with a crystalline mineral, to me the texture seems more or less right for that - not of course for a fully intact bivalve or steinkern. I.e split by a natural fracture and then heavily weathered. The two valves seem slightly out of alignment or a bit crunched, neither of which is unheard of with fossil bivalves... What else could it be? Some other fossil I haven't considered? If not a fossil, then what? Anyway all of this is admittedly uncertain until the OP comes back with a better/closer photo (if he does). Edited March 11, 2022 by Wrangellian Link to comment Share on other sites More sharing options...
Rockwood Posted March 11, 2022 Share Posted March 11, 2022 34 minutes ago, Wrangellian said: If not a fossil, then what? Turbidite. Plain old blob of mixed sediment. Link to comment Share on other sites More sharing options...
Wrangellian Posted March 12, 2022 Share Posted March 12, 2022 Huh.. I've never seen one like that. Link to comment Share on other sites More sharing options...
Rockwood Posted March 12, 2022 Share Posted March 12, 2022 Maine is littered with them. Some are fossils, some include fossils, some are surely just balls of lime mud. Link to comment Share on other sites More sharing options...
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