Collecting the Stages

[connorp]

1 hour ago, Wrangellian said:

Thanks Connor. I think you're right.. If it is a fossil (and there are lots of simple disc-like things from the Ediacaran that are doubtlessly organic), I doubt Namacalathus too, which is why I didn't mention it even though the seller called it that. But I guess it's more likely to be something geological/mineralogical, I just don't know enough to make a judgement on that. To me it doesn't seem like simple weathering, though; I think there must have been something in there that weathered out, if it didn't start out as a bubble.

Here is a picture I took at the Field Museum in Chicago a while ago. There was a series of specimens that showed some weathering process of sandstone. I don't think there was a description of what exactly was going on, or maybe I just don't remember. I'll have to check next time I'm there. Anyways, this rock looks very similar to many of the so called Namacalathus specimens I've seen for sale. Take this for what you will, I'm no expert, just pointing out the similarity.

[Wrangellian]

I know, I've seen pieces like that one too, as well as the larger ones that seem to have 'compound bubbles', and I have no idea! When I think of weathered sandstone, I think of this kind of thing, which I think starts as shallow dimples and gradually weathers into deeper holes. The piece you've shown looks as though it already had holes/bubbles or particles of some material that dissolved out much more quickly than the matrix weathers.

[Wrangellian]

I just rediscovered this specimen and, from what I can deduce from the literature I can find, it is Priabonian (Late Eocene).

 

[dinosaur man]

On 2020-05-23 at 6:25 AM, Wrangellian said:

Cenomanian:

A large, flattened Gryphaea sp from the Dunvegan Fm of Smoky River, Alberta

Nice specimen!

[Wrangellian]

Thanks, that was another of those bargain bin items at the gem/hobby show years ago, from the same seller if I recall. I've never seen another like it (nor have I seen that seller again, wish I could)

[Bobby Rico]

Very interesting thread with some

good specimens 

[Wrangellian]

Thanks for the comments, Bobby and everyone.

 

I've now got the Olenekian and Wuchiapingian, if my information is correct. Filling in some gaps on either side of the Permian Extinction. It would be nice to get something from those two small (st)ages immediately before and after the Extinction - the Changhsingian and Induan, but I expect those to be tougher for me to find.

 

Olenekian (I'm not collecting the substages at this point, but the info says Dienerian):

Pteronisculus cicatrosus, Sakamena Fm, Ambilobe, Madagascar.

 

Wuchiapingian (Late Permian):

Glossopteris sp., Dunedoo Fm, Illawarra Coal Measures, Dunedoo? NSW, Australia

 

[Wrangellian]

I meant to post the updated checklist... may as well do it now as it may be some time before I fill in any more blanks.

So I am still missing:

Holocene (all)

Pleistocene (all)

Pliocene (all)    (I have some Pleistocene and Pliocene fossils but not sure where they fit into the scale)

Miocene: Messinian, Tortonian, Serravallian, Aquitanian

Oligocene: Rupelian

Eocene:  Bartonian

Paleocene:   Selandian, Danian

Cretaceous:   Coniacian, Barremian, Berriasian

Jurassic:  Bathonian, Bajocian, Aalenian

Triassic:   Rhaetian, Induan

Permian:  Changhsingian, Capitanian, Wordian, Roadian, Sakmarian, Asselian

Carboniferous: Kasimovian

Devonian:  Famennian

Silurian:  Pridolian, Ludfordian, Gorstian, Sheinwoodian, Aeronian, Rhuddanian

Ordovician:  Hirnantian, Dapingian, Tremadocian

Cambrian: Jiangshanian, Guzhangian, Stage 2, Fortunian

 

[Wrangellian]

I forgot that this is equivalent to Famennian in age, so I've had that one all along also...

That completes the int'l Devonian stages.

Plumalina plumaria (feather coral)

Chautauquan, Perrysburg Sandstone (Canadaway Gp)

Almond, NY      -from John Spina

 

Edited March 26, 2021 by Wrangellian
better pic

[Wrangellian]

Another hole plugged: Rhaetian (topmost stage of the Triassic).

Polished slice (~13cm wide) of 'Cotham marble' (stromatolite),

Rhaetian, Penarth Gp, Lilstock Fm, upper Cotham Mbr,

Bristol, England.

Hopefully I've got all that info correct.

Edited March 28, 2021 by Wrangellian

[Wrangellian]

Updated checklist... I'm getting there

I'm checking off the Fortunian (lowest Cambrian) on the assumption that that age is correct for the Sabellidites cambriensis piece that I posted earlier (the species name seems to indicate so).

 

Edited March 28, 2021 by Wrangellian