Jalama "Rossil"

[MrR]

Greetings all.

 

In the spirit of tricks and treats today, I figured I'd post a slightly disingenuous ID question. Or maybe someone will surprise me and tell me that it actually is a fossil, rather than a "rossil". I'm not holding my breath.

 

I was camping at Jalama last week, when it was pushing 90 degrees on the beach. It was a pleasant couple of days but the weather made it less so than one would expect. I did end up breaking up a few cleavable pieces that came from a fresh fall at the back of the closest cliff to the South side of the campground, but found nothing. And it was too darn hot, and my old back was protesting the whole thing, so I gave up on breaking rocks in pursuit of Jalama's famous "exploded fish" (That was for you, Doren. RIP, buddy.). Instead I just took a little walk on the sand with my partner.

 

Aside from the joy of the Jalama beach hopscotch, i.e. skipping around and over gobs of tar seeps, we were just looking for interesting rocks, shells, etc. One thing I found was a thing I'll call a "Rossil". (I'd be surprised if the term hasn't been used before.), I'm 99.99% sure that it is indeed a "Rossil". I just don't know what it's from.

 

Anyway, it sure looks a lot like a vert, perhaps caudal, but it is very flat on one side. Of course that could be from the absolute geological crushing it has been taking through eons as it "rossilized".  So, what do the experts think of my rossil?  Keep it friendly, folks. Happy Halloween, all.

 

 

 

[MrR]

Flat side down, obviously.

[DPS Ammonite]

Being Halloween, we need to see the Devil. Show us the details of this part of the rock. A clearer photo is needed. I think that I see a quartz/chalcedony vein going through a siliceous rock. Differential weathering evident due to differences in hardness of the veins relative to the matrix. Any Monterey Fm. rocks there?

 

 

Edited October 31, 2022 by DPS Ammonite

[MrR]

Thanks, DPS Ammonite. I believe the formation at the bluffs is actually Monterey formation.  And yes, my first guess would be that the thin bands through the rock were some sort of quartzite. Sadly, my phone images were better than what I get with my old Sony 8.1 megapixel camera. I'll attach an image from the Sony, but I don't think it's as clear as the iphone X image. Cheers.