Daring to Hunt Centralia Ferns

[I_gotta_rock]

 

I read @rachelgardner01 's trip report* recently on the fossil forum telling about St. Clair-style white fern fossils and how the ghost town was once again being visited by more than just the most reckless of thrill seekers. Not long ago, extremely few people dared to go beyond the new bypass for fear of falling into flaming sink holes. The place has become unregulated like the Wild West, with tourists coming from all over to see the “Highway to Hell” and ride their ATVs. The fire was reported to have burned out in town and moved down the coal vein. Clearly, no one is worried about sink holes.

After a couple hours enjoying every ride with no lines at Knoebels Amusement Park on a very foggy, soggy day, we drove to Centralia for a little fun. What could be cooler than a ghost town on a foggy October day? And, by the way, after enjoying the romantic setting, maybe we could find the quarry.

Rachel's trip report included a handy aerial map with the slope marked in red. It was a short walk from on of three cemeteries that are still maintained in town. All we had to do was follow the ATV tracks.

We met a microbiologist while we walked. She was looking at the bacteria, comparing soil samples from places where the fire was out with samples from some hot spots above a fire that still exists deep below town (with surface soil temps around 80F). The bacteria present in the hot spots are out of balance. There is an overabundance of the wrong sort. However, in the spots that have cooled down, the balance has returned surprisingly quickly. And, by the way, she had a permit to be there. The town is still considered too unsafe for the general public, but it isn’t patrolled. Two lessons should be learned from this:

1.      Nature always finds a way.

2.      If the rocks I’m examining seem kind of warm, find someplace else to prospect!

 

We found the quarry about an hour before sunset. We found ourselves at the top of steeply sloping walls covered in scree over smooth, slick, carbon shale.  I watched my step, kept my center of gravity close to the ground, and tread carefully. I like sliding down scree-covered slopes, but not when I do it unintentionally.

The fossils were plentiful! I saw calamites and lepidodendron all over the place. Some were bright white while others were gleaming gray on matte gray shale. Some had a single fern frond and others were a riot of plant textures.  A few were coated pale yellow. The hard part was picking out the nicest ones to take home.

I have been to this formation before. I made several trips to Carbondale, to the NE, over the last couple years. I missed my chance to go prospecting at St Clair ( a few miles to the SE ) as they closed the site to all but school groups a few years ago, but I do have some pieces that others collected before they closed. St Clair and Centralia both have the white ferns. Carbondale has the most detailed preservation. The ones there that are colored are yellow to deep red with a few that have iridescent spots. Centralia’s stone is the most crumbly and delicate, especially when damp. Although Centralia, St. Clair and Carbondale are all part of the Lewellen Formation and reasonably close to one another, there is a distinct difference in the stone at each locale. St Clair and Carbondale have firmer shales.  I wanted to find things that I did not already have represented from Carbondale. That proved tricky in the short time I had, but I did find some nice white ferns to take home. Plus, I have a plan for another trip at some point with more time – maybe with some simple rappelling gear?

Coincidentally, this month’s speaker for the Delaware Mineralogical Society was a geologist who participated in a study of the mineralization of St Clair plants. Here, then, are some of the highlights after I thought to take notes.

Time period: Pennsylvanian Sub-period, 320-290 million years old

The environment was a swampy area where the sediments settled slowly. The plants were minimally compressed during preservation, so the impressions are more or less the same size as the original biomatter.

The silvery-gray material coating some of the plant impressions is graphite while the white is a combination of pyrophyllite and kaolinite after pyrite. When the swamp was buried, the thicker parts of the plants pyritized. Heat and pressure then transformed the pyrite into the white minerals, which settled to the bottom. The upper surfaces retained the carbon and became coated in glossy graphite. So, what one sees loose on the ground are a mix of upper and lower surfaces.
 

*

 

[Wrangellian]

Is that all you brought home this trip - those 2 pieces?

Glad to hear there are still places to collect Llewellyn Fm. plants.

[I_gotta_rock]

1 hour ago, Wrangellian said:

Is that all you brought home this trip - those 2 pieces?

Glad to hear there are still places to collect Llewellyn Fm. plants.

No, there is more. I didn't bring home a lot because I just couldn't see that well, but I filled my little backpack. I just haven't unpacked it to photograph yet. It's not far from Danville and Montour Preserve, so might make a weekend of it later.

[Wrangellian]

Be sure to post anything else that's worth showing.

[Monica]

Nice stuff!  Thanks for showing us some pretty flora 

[I_gotta_rock]

On 10/25/2019 at 7:40 PM, Wrangellian said:

Be sure to post anything else that's worth showing.

Here;'s a cool one,  close up.

Fern leaf highlighted with white pyrphyllite powder after pyrite. Note the veins visible in the leaves. The horizontal lines streaked across the frond are the superimposed impressions of a calamites (horsetail plant) leaf that was buried with it. The fern frond is less than 3 cm long.

[I_gotta_rock]

Calamites bark with yellow pyrophyllite highlights

[I_gotta_rock]

[I_gotta_rock]

Hash plate with 1 cm (+/- ) seed marked by a red dot.

[Wrangellian]

Are you referring to the Sphenophyllum-looking thing as the seed, or is it barely visible next to it?

[Bguild]

13 hours ago, Wrangellian said:

Are you referring to the Sphenophyllum-looking thing as the seed, or is it barely visible next to it?

 

The fossil noted as a seed looks to be annularia. @I_gotta_rock Nice looking finds! Similar preservation to carboniferous plants I've seen in southern Massachusetts.

[Fossildude19]

Nice report and finds!

I agree, ... not a seed, but Sphenophyllum, as Eric suggested. 

 

 

Link to Picture

[I_gotta_rock]

Thank you all for your correction. After I wrote seed, I started to wonder myself if seeds had even developed yet. I'm an invertebrate paleontologist. Plants don't have backbones however...

I finally got a fair-sized caboniferous plant field guide this summer, but have such a backlog of finds to sort that I haven't cracked it open yet.

[RandyB]

Congrats on a nice, albeit quick, hunt. I have been over there a few times lately though my trip reports have been severely lacking.

 

For those reading through who are coveting their own little piece of abandoned Centralia coal mine fauna, keep an eye out for the AWOL lot I from this years Christmas auction which will hopefully be posted soon. 

[Bguild]

3 hours ago, I_gotta_rock said:

Thank you all for your correction. After I wrote seed, I started to wonder myself if seeds had even developed yet. I'm an invertebrate paleontologist. Plants don't have backbones however...

I finally got a fair-sized caboniferous plant field guide this summer, but have such a backlog of finds to sort that I haven't cracked it open yet.

Seeds did indeed exist in the Carboniferous. I haven’t found many, but keep your eyes peeled.

 

[ynot]

Nice trip report and it looks like You found some nice fossils too.