Nodules Embedded In Siltstone..

[FossilFisher]

Hey there, I've been fossil hunting in Iowa for a few years now. Not in the best areas, but I make do. Recently I was walking the Des Moines river in Boone Co. IA. The area is said to be the Cherokee group by the USGS, specifically they call it either Atkoan or Morrowan. Although there is also a "Desmoinsian" bed that some books mention. The age of the outcroppings are middle pensylvanian. Most of the cherokee is shale, coal, and some sandstone and limestone. It comes from a sandstone ravine that's about 2 miles north of the area called Ledges state park. Which was a part of a huge delta from a river at the time comming from Minnesota.

Onto the pictures, the peice was found as-is. Rusty brown nodules imbedded in either sandstone or siltstone, its pretty fine grained. One of the nodules has little dots going up the side of it. The rest look pretty worn down. I really haven't any idea, except for maybe seeds (which we're only just evolving at the time), maybe amphibian eggs?

The other pictures are just for fun and reference, peices of what seems to be calamite, and annularia found in the area. Let me know if you think they're something else. This is my first post here, let me know if I screw up the pictures.

Edited November 27, 2012 by FossilFisher

[Missourian]

Welcome to the forum.

1 & 2. I'm not seeing any fossils.

3. Calamites yes.

4. Interesting. Do you have closer photos?

Regarding Cherokee, Demoinesian, Atokan, Morrowan.... The Pennsylvanian in the Midcontinent consists of five stages. From bottom to top, they are Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian. The Cherokee is the lower group within the Desmoinesian. The Marmaton is the upper group.

[Auspex]

I wonder whether your 'nodules' might be clasts; river-tumbled chunks which were deposited in what was to become a sandstone layer?

[Herb]

Welcome!

I think the first 2 are mineral in origin

third possibly Calamites

forth possibly worm burrows (but very cool looking) more closeups would be nice!

[Missourian]

I think I may be seeing 'segments' in the things in the last image, but it may be the pixels playing tricks on my eyes.

[FossilFisher]

If they are annularia, they dont appear to be still part of the plant, I was figuring maybe they were collected by a river and locked in a huge slump (there are tons of them). The rock seems to be limestone.

[FossilFisher]

Also I've been reducing the pictures from like 3000px down to 800. Does that destroy too much quality? I didn't think I should leave them huge like that.

[FossilFisher]

Well thanks for the info guys, I really appreciate it. And auspex that is a really good idea, I'm half tempted to get them out to see what they really are. But river tumbled rocks seems like a real possibility. Its still neat that they might be 300 million year old pebbles lol.