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Norcross, GA 30093-3059

GMS Field Trip December 2021

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GMS Field Trip
Mississippian Fossils & Geodes in Tennessee
Saturday, December 18, 2021


Rain made us delay this trip for a week, then decided to tag along with us during the rescheduled trip. The day started a bit soggy, but cleared up long enough for everyone to collect a few coral fossils nearby before the caravan headed off. When we arrived at the main collecting site, we could see that crinoid fossils were abundant and easy to find. Within a few minutes of hitting the ground, everyone found several crinoid stems, as well as plates with crinoid stems. Some crinoid stems had a star-shaped pattern in the center, so with a nod to Dr. Seuss, we nicknamed them “star bellied sneetches,” then delighted in the search for our stellar friends. Junior members had great success finding unusual stems, bryozoans, and other curious fossils. A few elusive calyxes went home as prizes too.

After a quick lunch break, we headed off to find geodes. The rain that played with us that morning returned to taunt us that afternoon as we hiked to the geode location, but it tapered off just in time for some geode collecting fun. Everyone found a few geodes before the rain visited again, a little more adamant about chasing us away. And yet, the intrepid group was not going to let a little rain dampen its spirit, so we continued collecting. Alas, it wasn’t long before a brisk breeze swept over us and we realized it was a sign of things to come. We could have stayed a bit longer, but everyone was happy with their geodes, so we packed up our prizes and hiked out. We bid each other adieu and returned home to dream about crinoids and geodes and our magical day of shared adventures.

Lori Carter
On behalf of Charles Carter, Field Trip Chair
e-mail:

Coral

Photos by Lori Carter

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Members made small piles of fossilized coral to take home
Photos by Lori Carter

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At first, this one looked like cross sections of shells,
though on closer inspection, it appears to be something else.
But what is it? Maybe crinoid or blastoid stems?
Photos by Lori Carter

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This one looked like a shell at first too, but maybe not?

Crinoids

Image by Maryland Geological Survey

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Basic stalked crinoid anatomy
The crinoid fossils we collected are about 330-347 million years old.
Image Credit: Maryland Geological Survey E.S. No. 4, p. 38, Fig. 35
Photo by Lori Carter

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Plenty of crinoid stems!
Photo by Lori Carter

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Pretty little plate of crinoid stems
Photo by Lori Carter

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A sharp-eyed junior found this oval crinoid stem segment
Photo by Lori Carter

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This spiky crinoid stem is another excellent junior find
Photo by Lori Carter

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This cool stem with a pattern resembling a spider web was also found by a junior!
Photos by Lori Carter

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Star bellied sneetches!
Photo by Lori Carter

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This little stem is completely circled by fossilized goo
Photos by Lori Carter

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A crinoid stem preserved with the interior structure visible
Photos by Lori Carter

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First calyx of the day!
Photos by Lori Carter

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Another calyx!
Photos by Lori Carter

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And another calyx! Notice the fine details preserved on the bottom of this one.
Photo by Lori Carter

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Gorgeous calyx!
Photos by Lori Carter

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Last calyx of the day! Cute little "baby blue" Agericocrinus
Photos by Cristina Clines

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Plate chock full of crinoid fossils including what appear to be 2 partial calyxes!
Photos by Lori Carter

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Example of a plate of crinoid stem columnals
Charles ground the bottom of the plate so it would stand up as a nice display
Photos by Lori Carter

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Most stems and plates we find are round, but this plate has oval columnals!
(Photographed wet. The rock, not me)
Photos by Lori Carter

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This is a sedimentary rock composed almost entirely of crinoid stems!
Crinoids were so plentiful that a rock like this is not uncommon.
In fact, they have their own name -- "encrinite".
Photo by Lori Carter

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Calyx from a prior trip posing on a book that was available only a few days before this trip:
"Collectors Guide to Fort Payne Crinoids and Blastoids" by William Morgan
Photos by Lori Carter

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What is the stuff on the crinoid stem? Is it something coming out, or something going in?
Though I could not find much information on what happened to crinoid stems like this one,
it could be a process called "geodization", whereby silica bloats and distorts a fossil as it expands from the inside.
Photos by Lori Carter

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Multiple views of a puzzling crinoid fossil. Is it a calyx? Arms?
It has been tentatively identified as a partialy "geodized" calyx missing its cup

Other Fossils

Photo by Lori Carter

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Horn coral (left) and brachiopod (right)
Photos by Lori Carter

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Juniors became quite skillful at finding bryozoans in the shale
Photo by Lori Carter

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This brachiopod specimen includes the fossilized shell as well as an impression in the shale
Photos by Lori Carter

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One of the juniors found this superb shell in shale
Photos by Lori Carter

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At first glance this looks like a crinoid stem embedded in the rock.
But take a closer look and one may question that.
The matrix is thin, and the fossil fairly flat. But if not crinoid -- what?
Photos by Lori Carter

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Hard to tell at first, but a close look leads us to branching bryozoans

Geodes

Photo by Lori Carter

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One of the juniors found some nice geodes already broken open!
Photo by Lori Carter

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The crystals in this geode have a lovely orange/red color
Photo by Lori Carter

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One junior got good at breaking open geodes and took home this beauty!
Photos by Lori Carter

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Geode hunting before the rain...
Photo by Lori Carter

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...but even when the rain came we kept on going...
Photos by Lori Carter

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...then the wind finally convinced us to call it a day
Photo by Lori Carter

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Saw this little "fun guy" on the way in and stopped to say "bye" on the way out
Photo by Lori Carter

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One of the juniors spotted this little guy
Photo by Lori Carter

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The moon peeked down at us from behind the clouds on our way home

Hong, Eugeneah, and Caden's Favorites

Photos by Hong Thov

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(Top) Fossil corals all cleaned up
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(Bottom) A piece of a calyx (left) plus two crinoid calyxes! (right)
Photos by Hong Thov

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This is the first time we have seen this type of branching bryozoan at this location!
Photos by Hong Thov

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This is probably a crinoid stem, but if it is, it's really flat!
Photo by Hong Thov

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An impressive assortment of crinoid stems and plates
Photos by Hong Thov

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Geodes!
Photos by Hong Thov

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Geodized coral!

Alex and Sarah Kate's Favorites

Photos by Kallie Brunson

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Juniors show their favorite finds from the trip
Photos by Kallie Brunson

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A beautiful geode filled with sparkling quartz crystals
Photos by Kallie Brunson

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A geode that has yet to be cracked open

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