Sunday, July 25, 2021

Hunting

When I was very little, maybe four or five years old, my mom and my aunt took my cousin and I to a natural history museum. I don't remember very much about the experience, except that the day's grand finale was the chance to apply what we'd learned about fossils and conduct a dig of our own.

My long-suffering
plaster trilobite
This "dig" took place in a sandbox. Our tools were plastic shovels and colanders, and the fossils turned out to be identical plaster copies of the same trilobite. Every kid who participated got one to keep, and I'm sure the second we left the staff got to burying more for the next group to find. The entire experience was about as spontaneous and unpredictable as a trip to the petting zoo.

And yet I still vividly remember finding those trilobites. My cousin and I both still have them (although he's managed to keep his in pristine condition, while mine has been broken and super glued and is now missing a piece of its back. You could take that fact and draw some conclusions about the ways that we're different, and you probably wouldn't be wrong).

I'm still not sure why that day made such a big impression on us. While I can't speak for my cousin, I can say that I've been fascinated by fossils and paleontology ever since. Trilobites in particular hold a certain allure--I've always wanted to find a real, complete trilobite fossil to match the plaster one I've carried for years.

That was my goal this weekend, then, when the Indiana Society of Paleontology resumed hosting field trips after a hiatus for COVID-19. I put on my steel-toed boots, packed up a hammer and hard hat, and drove out I-74 to meet the gang at the quarry.

The St. Paul Quarry

As fossil sites go, quarries have their pros and cons, but there's obviously a huge advantage to the fact that someone else has done the deep digging. The St. Paul quarry seemed especially promising, since it would likely have older stones by virtue of being in the southeastern part of the state.

This particular site was also loaded with shale. Shale's a fun stone to excavate because of the satisfying way that it splits. Each time you crack a stone in half it feels a little like playing the lottery. Mostly you get nothing, but once in a while you find a real gem.

Splitting a stone
with my trusty (and rusty) hammer

Although we visited the quarry over a weekend, when most of the workers were gone, there was still some heavy machinery moving down in the pit, and we were warned to stay up top for our safety. 

While it's nice not to get flattened by excavators, the drawback was that we were left at the mercy of whatever rocks had been dumped, higgeldy-piggeldy, around the top of the pit. If you found something promising, there was no guarantee there'd be anything else like it in the immediate area. Even so, it wasn't long before I found big chunks of fossilized seabed with a bounty of shells and corral.

Ancient seabed

What looks like rough stone at first turns out, at a closer glance, to be chock full of bivalves and brachiopods. By now I've learned to spot these fossils at a distance pretty quickly, but it took some practice to get very familiar. Having never spotted a trilobite before, I wondered if I would even recognize one if I actually saw it.

A growing crystal of pyrite

While scouring the stones, I found was a whole slew of brachiopods growing pyrite crystals (fool's gold) around their shells. I'd never seen this before, but apparently it isn't uncommon, especially in shale. By the time I was done I'd collected several more samples of pyrite, both growing on fossils and all on its own. Not quite what I was looking for, but a fun find nonetheless.

A tale of two tails

Then, finally, toward the end of the dig: a pair of trilobite tails. As it turns out, carrying a plaster cast of a fossil for thirty years is a pretty good way to burn its appearance into your brain. As soon as I saw that striated, three-column structure, I knew what I had.

While it would have been fun to find a complete fossil, this wasn't too bad for a morning's hunt. It's also good practice. On each excavation I seem to make my finds quicker, and get a better sense of how to find what I'm after. I just need a little more practice, and a little more luck.

People Watching

On Wednesday, I went out to meet up with a friend and do some writing. We met at the Athenaeum, a historic building in Indianapolis designed...