Pierre Shale Pictorial Trip Report

[Thomas.Dodson]

A few weeks ago I had the opportunity to look for fossils among additional Pierre Shale outcrops in the Sheyenne River Valley. I didn't post anything about that trip as it came up a bit short and read like my last Pierre Shale trip with more partial specimens. Today I went back to the area to look again, and also made it to an outcrop of the Gregory Member. Low water levels made for a great collection from the Gregory. The DeGrey was rather typical.

 

The side of one of the so-called "Indian Mounds" of the DeGrey member and a frog which was hanging out on the mound.

This portion of the river is also the DeGrey. The DeGrey is well exposed in many parts of the state but is often poor in fossils. That fantastic looking ravine produced nothing, not even fragments.

Glacial till and boulders are often mixed into the worn outcrops.

Some things still grow in the worn shale. Prairie Crocus (Anemone patens) coming up from a few weeks ago.

Exposures of the Gregory.

The mark of the Gregory, tan claystones compared to the mark of the typical DeGrey, iron manganese carbonate concretions.

Frogs were everywhere. I counted 19 frogs in a 7 foot line along the bank here. Freshwater mussels are abundant in the Sheyenne and the low water beached several. Many became muskrat and raccoon snacks. This male Fatmucket (Lampsilis siliquoidea) was one that survived the feast. 

The first fossil from the Gregory, a nice Baculites.

 

 

[Thomas.Dodson]

It certainly wasn't the last Baculites. I believe most, if not all, of these are Baculites gregoryensis. Mind the poor pictures, I think I dirtied my lens for these.

A fragment of Solenoceras mortoni.

A Didymoceras fragment.

One of two Nucula sp. This one appears to be Nucula planomarginata.

Some gastropods in varying degrees of preservation. Second from right is probably Trachytriton sp. (Yes, the one on the right is a gastropod. It has certainly seen better days!)

Your typical DeGrey invert fauna, Inoceramus and Pteria fragments. Some had original shell. I do like the one with Inoceramus piled on each other.

Two Baculites that came from the DeGrey.

And a little chunkosaur from the DeGrey as well.

 

 

[hadrosauridae]

Great writeup, I enjoyed it!

[Fossildude19]

Excellent report, pictures, and finds!

Thanks for showing us!  

[Myrmica]

What a wonderful day out, and a lovely haul.  

[Ludwigia]

Very good report and nice finds! Thanks for sharing.

[Wrangellian]

Ditto.

Hmmm... those baculites look a lot like ones that I acquired from an old rockhound over here years ago, without any ID/location data. Forumers have suggested they are in all likelihood Pierre Shale, with suggested sites in South Dakota or Montana. No one suggested an ID and North Dakota was not specifically mentioned, but I assume they are widespread throughout the formation..?

We get a lot of those Inoceramus shell chunks here, sometimes layered on top of one another like that piece.

I like the mussel... the patterns remind me of 'sunset' surf clams. I never would have thought bivalves could be found in freshwater, especially rivers, until I found some in a river over here some time ago.

Edited May 20, 2021 by Wrangellian

[RJB]

  Love all the pictures.  and its funny how huge area's have nothing and then you hit a spot full of fossils.  Have a huge area north of me just like that. 

 

RB

[FossilNerd]

Great report and finds! Thanks for sharing.  

[Nimravis]

Great report, finds and pictures.