04 Sep 2021: Small plant impressions at Belt, MT

[kehaz]

Upon doing some research on exposures near Great Falls, and from a tip I received from a fellow member of my local prospector's group, I found an exposure just outside of Belt that is somewhat known for its plant fossils. Roadside Geology of Montana has this area of the state marked as early Cretaceous, but the large Jurassic coal seam cutting through the middle of this exposure was apparent as soon as I parked. I scrambled up the loose shale and sandstone to the seam, where I almost immediately began to spot small impressions in the dark-gray shale.

 

 

 

 

The shale was incredibly fragile and would often crumble at a slight touch, and it was a new experience for me in handling rock that didn't need a hammer and chisel to split. I spent most of the trip sifting through the loose shale that had slid from the exposure and gently prying open larger pieces with my fingers or a small, thin chisel. This was definitely an exercise in patience, as I had to really slow down and be gentle with the shale as to not shatter the pieces in my hands. After about 2 hours, my husband and the dog were incredibly bored, as their adventure down to Belt Creek was unexciting, and the heat was getting to them. So, as is often the case with my hunts, I had to leave earlier than I wanted. But I am incredibly happy with my finds, small as they may be, and I plan on returning to this little spot soon.

 

I'm not too familiar with plants in this area, as most of this part of the state is Cretaceous or Mississippian marine, so if anyone would like to offer some IDs, I would love them! I'm trying to be diligent in cataloguing all my finds, so anything helps!

 

 

 

Some of them really shine when wet, as I found when I was cleaning them up. The dark-gray of the shale is also much more apparent.

 

 

 

 

 

 

I know they're small and not particularly impressive or rare, but I am incredibly happy with my little haul.

 

Thanks for stopping by on my adventure; I hope you have a great day!

[minnbuckeye]

I find them very impressive!!!!!! Eyes of the beholder I guess.

[kehaz]

7 minutes ago, minnbuckeye said:

I find them very impressive!!!!!! Eyes of the beholder I guess.

 

I guess when I think of "impressive," I think of large and unbroken specimens. I'm not jaded, I swear! I absolutely love all of my little fossils, no matter how small or fragmented they are!

[Fossildude19]

Nice finds for sure.   

Thanks for posting.

 

[Plax]

Amazing how similar plant fossils look over huge amounts of time. How did you determine that the coal was Jurassic instead of early Cretaceous? Great fossils!

[historianmichael]

Awesome finds! We don't see Mesozoic plant material posted here often. Very cool!

[tombk]

Thanks for sharing your pics. I find them interesting. 

[kehaz]

10 hours ago, Plax said:

How did you determine that the coal was Jurassic instead of early Cretaceous?

 

Roadside Geology of Montana talks about the black-shale Jurassic Morrison Formation laying directly underneath the sandstone Cretaceous Kootenai Formation in exposures along Belt Creek and the eastern part of the Great Falls-Lewiston coal fields. It also talks about how the Sevier orogeny event buried the Jurassic swamp deposits under the mountains that raised up throughout the Cretaceous. I have also read a few geological and coal surveys that examine these two formations and how they essentially butt up against one another, but I don't believe that the surveys get too close to Belt city limits, which is about where I was finding the impressions. So I suppose I don't know for 100% sure if it is late Jurassic or early Cretaceous, but based on the research I've done, I'd bet on Jurassic. Feel free to correct me, however; I try to do my homework but I'm not a professional

 

Here's a few of the surveys I've read:

https://deq.mt.gov/files/Land/AbandonedMines/documents/CoalDocuments/GTFCoalField_HistoricOverview.pdf

https://mbmg.mtech.edu/pdf/geologyvolume/Gunderson_CoalGeologyFInal.pdf

Edited September 9, 2021 by kehaz
Fixed geographical info about coal field location

[Plax]

On 9/9/2021 at 7:13 PM, kehaz said:

 

Roadside Geology of Montana talks about the black-shale Jurassic Morrison Formation laying directly underneath the sandstone Cretaceous Kootenai Formation in exposures along Belt Creek and the eastern part of the Great Falls-Lewiston coal fields. It also talks about how the Sevier orogeny event buried the Jurassic swamp deposits under the mountains that raised up throughout the Cretaceous. I have also read a few geological and coal surveys that examine these two formations and how they essentially butt up against one another, but I don't believe that the surveys get too close to Belt city limits, which is about where I was finding the impressions. So I suppose I don't know for 100% sure if it is late Jurassic or early Cretaceous, but based on the research I've done, I'd bet on Jurassic. Feel free to correct me, however; I try to do my homework but I'm not a professional

 

Here's a few of the surveys I've read:

https://deq.mt.gov/files/Land/AbandonedMines/documents/CoalDocuments/GTFCoalField_HistoricOverview.pdf

https://mbmg.mtech.edu/pdf/geologyvolume/Gunderson_CoalGeologyFInal.pdf

Me either! Just asking.