Cambrian puzzler

[Fossilizable]

While out on a trilobite hunt several years ago in the Marble Mountains, San Bernardino Cty, CA, I found these two pieces on the surface in the region of a Latham shale exposure, so I think they would have belonged to the Chambless shale, which is in fact exposed as a bluff above the surface. Here's one:

 

 

 

Here's the other:

 

I'm not sure about these. They might not even be organic or in the same genus if organic. The source field might be a zone with Chambless and Zabriskie quartzite mixed. So there's a chance they're inorganic, I guess. However, on the same surface/field we found a lot of fossiliferous rock that included oncolites, which are definitely known to be in the Chambless. What do you think? 

[Sagebrush Steve]

I’m no expert but the first one looks geologic to me.  The second one is more intriguing but I’m not sure what it is.  As I recall, the Marble Mountains have a mix of Precambrian and Mesozoic deposits in addition to the Cambrian deposits where you find the trilobites.   If these were on the surface they could have come from any of them.  But I will defer to the experts.

[pachy-pleuro-whatnot-odon]

Hi, and welcome to TFF! We've got many friendly and knowledgable people on here, though with respect to the Marble Mountains I'm unfortunately not one of them

 

In a general sense, however, judging by how little differentiation there seems to be between the matrix (rock itself) and the would-be fossils, I'm thinking that @Sagebrush Steve might indeed be right in these simply being geological features. But, lets wait for some experts to come by and see what they think. Don't despair if your question is not answered immediately, though, as it may take some time for the right person to come along to help you

[Rockwood]

I can imagine it being a mold fossil preserved on the under side of an ash layer. It's just a thought though. 

[LabRatKing]

Appears to be ripples from the bottom of a body of water to me. (There is a word for that, but I am pre-coffee at the moment...)

 

 Might be an ichnofossil, but even that is a stretch.

 

My vote is for geologic in origin however.

[pachy-pleuro-whatnot-odon]

1 minute ago, LabRatKing said:

Appears to be ripples from the bottom of a body of water to me. (There is a word for that, but I am pre-coffee at the moment...)

 

 Might be an ichnofossil, but even that is a stretch.

 

My vote is for geologic in origin however.

Yeah, these two options also crossed my mind, but, in the end, I too settled on geologic...

[Fossilizable]

Thanks for the replies. My difficulty with these being ripple marks is that they're so small. Even capillary waves need a couple centimeters of wavelength, but these look like they'd be measured in mm. On the other hand maybe there's a different rule for turbidites? In any case both certainly have the look of asymmetrical ripples, perhaps of the linguoid variety. But just too tiny! And to be clear, I'm thinking of these only as trace fossils, if fossils at all. I doubt the dark color is significant.

Edited February 25, 2021 by Fossilizable
Turbidite ref

[IsaacTheFossilMan]

The third one looks like a ripple from sand or whatever the sediment was inside the water. Thus, it'd be designated a 'pseudofossil'. The first two, however, I'm not seeing ripple marks.

 

Cross-laminae comes to mind, I think that's the right term? When identifying it, a key feature is the gentle slope (up-current), and the steeper down-current slope. The effect I believe is called bedform, which can result in dunes or ripple marks! 

 

I've not personally heard of ripple fossils with ripple heights of much less than a centimetre (0.4 inches) - they're classed as 'very small'... Very inventive name!

[Sjfriend]

I was just there in January. I found a couple that looked similar, not exact but close. My thought when onsite was geological in origin. Though I also wondered if they could have been algae mats? It was definitely not associated with the oncolites.

 

My guess from looking at the pieces I had in hand is geological .