fossiling.com

Sleepless in St. Leon

St Leon , IN


In the movie “Breaking Away” much is made of the fact that Indiana University is built of and on limestone. Bedford limestone, which, it turns out, is composed mostly of fossils. A friend who’d grown up in Bloomington related finding Life Saver shaped stones in the creek behind her house that she used to string into necklaces. Those little rings were the shattered columns of crinoids, fossil sea lilies. When I was invited to IU for a job interview I knew I had to make time to do some fossil hunting. But I have to admit crinoids didn’t excite me, I’d already found platters of crinoid hash in upstate NY. While it would be a thrill to find a tentacled calyx -- the sea lily's "flower" -- my understanding is those are elusive trophies. I wanted better odds, and besides, I’d become fixated on other quarry altogether.

 

I’d read that the Cincinnati Arch, a geological formation stretching under three Midwestern states, was packed with marine fossils from the Upper Ordovician, some 450 million years ago. The majority of species preserved from this pre-piscene environment were brachiopods and bryozoans, shellfish and reef building colonial animals. These are not what lured me. I was after Flexicalymene meeki, little trilobites renowned for the beauty of their preservation. I had acquired a field guide for the Cincinnatian that gave directions to various collecting sites, many, as the name would suggest, in Ohio. But there was one tantalizing prospect just over the state line in Indiana. Saint Leon looked to be about 100 miles straight east of Bloomington. I had only one day for the round trip, but I reckoned that unless I got the job who knows when I'd be back, it was now or never.

 

The night after my interview I booked myself into a motel on the edge of campus, right across the street from a rental car lot. This seemed like a good idea at the time. It turned out that street was a main artery with traffic whooshing noisily all night. I slept badly and rose blearily, determined to get on the road as early as possible. First I changed motels for the coming night to put some distance between myself and that infernal intersection. Then I hightailed it out of town.



 

There is no interstate headed east out of Bloomington so I spent the first few hours on local roads. Southern Indiana is hillier than one might expect. Under the barren trees of late autumn the landscape seemed startlingly agitated: steep, closely packed hills plunging into deep gullies. I wound along narrow river valleys and crawled through small town traffic. I eventually emerged into more level, open land as I intercepted I-74 descending from Indianapolis. My field guide told me I was passing from Mississippian, through Devonian and Silurian strata as I crossed to the eastern edge of the state. I was traveling from younger geologic eras toward the ancient Ordovician core of the Cincinnati Arch, effectively moving backward in time. Once on the interstate I was able to accelerate this process. Still, I didn’t make the exit for Saint Leon until almost noon.

 

There wasn’t much there off the highway, a gas station perched on a barren hilltop. The weather was blessedly mild for early December, snow had yet to cover the ground. I headed north on Route 1, one eye on the odometer. When I’d gone 4.3 miles I pulled over onto the wide shoulder. I was in the middle of a big downgrade. An enormous road cut a quarter mile long rose in terraced slopes to either side like an inclined canyon. Trucks and vans roared down the hill every few minutes, honking as they flew by. They seemed familiar with the sight of strangers parked along this remote stretch, and I imagined bemused encouragement in the shriek of their horns. Doing a quick reconnaissance, I scrutinized chunks of rock that had fallen to the curb: they were packed with brachiopods. This, I thought, must be the place.

 

         

The roadcut at St. Leon;  A dense slab of compacted brachiopod shells.


I gathered my tools and started combing the eastern embankment beside the car. The steeply rising ground was a crumbly, gummy mixture of rock and clay. This would be hell after a hard rain. But fossils were everywhere, brachiopods virtually spilling out of the hillside. Flat Rafinesquina ponderosas, some the size of half dollars, were often cemented to slabs of gray rock. Marble-like Lepidocyclus capax were weathered free with both valves conjoined in the round. Most of the fossils were a curious pale rose color. And the preservation was stunning, better even than the Devonian fossils I’d collected from the cliffs of Lake Erie in NY, and older. Most impressive were the horn corals Grewingkia canadensis, bigger than my thumb and often revealing the folds of their inner septa intact.


3" Grewingkia horn coral; impression of a common gastropod Loxoplocus bowdenia.

 

But I had come for trilobites. I knew they were small, maybe a half inch across enrolled. I got my face close to the slope and peered intently at the muddle of rubble, clay and fossils. Certain small, ribbed Platystrophia brachiopods made my heart leap in false alarm. But it only took a half hour’s searching to bag my first flexi, its cephalon smiling, eyes perky as a Smurf, curled up in a ball like a corrugated pearl. I was accustomed to the trilobites of Western New York, mostly scattered Phacops molts, the enrolled specimens usually crushed and distorted like tectonic roadkill. So I marveled at the preservational perfection of this little arthropod.

 

I continued my hunt, climbing to an upper layer where branching bryozoan fragments tiled the ledge underfoot like pavement. Across the road I stumbled on a few examples of an unexpected and charming phenomenon: hollow brachiopods with crystals lining their interior walls. I found a nice gastropod there too. But it was another couple of hours before I found another flexi. At that point, exhausted, I decided to call it quits.

 


Three angles on my best Flexicalymene, just shy of half an inch across.

If only I had had the sense to retire to my car for a nap. But I had been invited to a party back in Bloomington and was, in light of my job prospect, eager to sample the local social life.

 

The sun was getting low over the furrowed fields of eastern Indiana as I sped back onto the interstate. The first fruit of my fatigue was I missed my turnoff. Suddenly I was going miles out of my way. Loathe to retrace my tracks, at the next exit I foolishly set out across rural back roads in search of a shortcut. The agricultural landscape grew ominously monotonous in the darkening twilight. Bloomington was far enough away that locals were clueless which direction to point me. As I anxiously negotiated fitfully marked tractor paths, impatient farmboys tailgated at speeds I wouldn’t dare on open freeway. It was past dark by the time I regained the route to Bloomington, which I appreciated more and more as a cosmopolitan oasis in this Kalahari of corn. The worst was yet to come. As the road wove into the black hills of the western end of the state I found myself weaving all over the road.

 

Somehow I made it to the party without catapulting over a guardrail and plunging my rental car into an inky ravine. While moms made Christmas ornaments I demurred drink and examined slabs of crinoid-riddled limestone their kids had found out back. At that point I was just glad to be alive.

 

I didn’t get that job in the end, so I was especially happy to’ve made the pilgrimage to Saint Leon with its splendid fossils. On arriving home I received an e-mail from the president of the Cincinnati Dry Dredgers, an Ohio based fossil club that I had queried before my trip. He was sorry he hadn’t reached me beforehand, but glad I’d found some trilobites. He wrote that many people go out there with high expectations and come away empty handed, as far as flexis are concerned. He went on to describe the best strata for finding trilobites, information that would have been good to have had on my visit. But I was not upset by this news. It gave me all the more incentive to go back someday. Hopefully after a good night’s sleep.




Roadcuts of the Ordovician

Saint Leon • Maysville • Orphanage Road • Georgetown • Caesar Creek

 

I returned to the Cincinnatian some 5 years later, driving out with a friend over a long Memorial Day weekend. It’s a 12 hour hump from New York, too much of it in Pennsylvania, with its incessant roadwork and diabolically varying speed limits. Across Ohio dead deer were such frequent sights along the highway they could have been mile markers. We drove on, braving torrential rain and the worst gas prices on record, buoyed by the promise of fine Ordovician fossils ahead.

 

The skies cleared the next morning as we drove south into Kentucky to meet our colleagues from the New York Paleontological Society. We caught up with them at a steep suburban road cut on Orphanage Road. This slope is blanketed in gravel and silt, products of erosion on the soft strata beneath. Fossils were much in evidence, tiny crinoid stem segments seemed to constitute entire layers of rock. The site is famous for its Cryptolithus trilobites. Their lacelike collars -- like tiny cow catchers on the front of their cephalons -- peppered chunks of rock or floated free in the dried mud. These delicate fragments are common, but full, articulated specimens are rare. And while the sun shined on us that day, fortune did not.




























 Kentucky sites: Cryptolithus "collars" Orphanage Road; cephalopod; giant roadcut, Maysville.


Following a tip to another site off the club itinerary, we drove eastward on Route 9. In this part of the country most rock formations are buried under topsoil and vegetation. Roadcuts are then windows into the geology that is everywhere under the surface. As we passed cut after cut we wondered if there might be fossiliferous strata exposed at any one of them. A missed turn gave us an opportunity to test that hunch. Before pulling a U turn we jumped out of the car to check the wooded slope just off the shoulder. Within a minute of scanning the scattered rocks Gordon let out a whoop: he'd found a nice sized orthocone cephalopod weathered out on the open ground. I was only seeing humbler fossils, so when he collected another in short order I began to get jealous. Finally finding a 2 incher of my own, my envy was placated enough to get us back on the road.


We switched to Route 8, a smaller road that ghosted the Ohio River. Passing dilapidated barns and muddy tributaries, the big river was ever present, flickering through the trees or rolling beyond a field, it was a charming drive. Just outside Maysville, KY we turned south onto Route 68 and straight into a roadcut of humongous proportions. Ragged, rocky terraces climbed 10 stories on either side of us. We spotted a couple of our Paleo Society pals prowling over these ledges and pulled over to get the skinny on the site. We ate our lunch sitting on the lowest terrace, dangling our legs over black strata riven with serpentine bryozoans, tangled like clusters of ossified earthworms. This looked promising. The terrace above was paved with pebbles come to rest in their descent down the slope. A bit of crawling on my hands and knees was rewarded with an enrolled Flexicalymene trilobite. Almost complete, but squashed, it was bigger, though not as nice as the ones I'd collected at St. Leon years before.


While there were fossils about, they weren't coming as thickly as all this rock seemed to promise. So we climbed higher, ultimately clambering about 2/3s of the way up the cut, venturing out along each terrace we gained. But besides some nice slabs tiled with Rafinesquina brachiopods, the joy to effort ratio was not in our favor. It was late in the day when we trundled back to the car and headed north into Ohio.

 

We decided to hit one more site on our way back to our Cincinnati motel. A half hour later we arrived at a cliff-like roadcut just north of Georgetown. This stop was on the club's agenda, but our friends were long gone. They did leave us fossils though: big Platystrophias



Waterfall, Georgetown, OH
and other brachiopods were abundant in the talus. But the real bonus was a waterfall across the road. Spilling over the same shale strata this cataract liberated fossils and piled them around its perimeter with the rest of the rubble.

 

The next morning we drove westward into Indiana, my return to St. Leon. Here our fellow members were crawling all over the roadcut – the east face anyway, out of the hot sun. As on my previous visit, big horn corals and a variety of brachiopods were abundant, but I immediately set to scanning the slopes for trilobites. I was interrupted by an introduction to a rep from the Cincinnati Dry Dredgers, the regional fossil club. He confirmed I was indeed hunting in the best layer for Flexicalymenes, the Liberty Formation. I found a couple of faces, cephalons, but after four hours of scrambling up and down the slope, that was about it. With all the gear I packed in my fraying toolbag, I must’ve forgot the luck. And nobody else was doing any better, as far as trilobites were concerned. The Dry Dredgers had been there the day before, could they have picked the entire cut clean?

 

Gordon and I debated our next move: go north with the group to Richmond for more roadcuts and brachiopods? Or start heading east to get a jump on the drive home so we didn’t  have to do it all the next day? Weary of roadcuts, we headed east.

 

But we did make one last stop. Veering north in Ohio we made for Caesar Creek State Park on the eastern edge of the Cincinnati Arch. There the spillway from a dammed lake is a famous -- and very public --  fossiling site. To collect you’re required to get a permit from the ranger station so we stopped there first. The ranger who helped us was working on her paleontology Ph.D and all excited to give us advice on the best spots.  We also picked up some guides to the region’s fossils at their bookstand and ogled an immense 13’’ Isotelus maximus trilobite that was unearthed in the park.


Caesar Creek; Rafinesquina; tiny Flexi tail by 1" Leptaena; 1 3/4 inch Isotelus genal spine.

 

We drove down to the spillway, an immense flat channel between low ridges. We had been advised to follow the righthand ridge and get as far from the road as possible. So we tramped down toward the far end of the spillway where it dropped off down a wooded slope. The afternoon was a hot one. Every now and then we’d stop and get low to the ground to see what was between the weeds. There were fossils, small examples of now familiar brachiopods, bryozoans and crinoids, as well as hints of trilobites: a tail here, a weathered cephalon there. I took a photo of a Leptaena brachiopod which upon later examination revealed an almost microscopic Flexi tail protruding from the matrix beside it. At the end of the spillway there was more rock exposed, and more brachiopods. I turned up some Isotelus genal spines. But that was about it after an hour plus of looking. They say people find still find nice trilobites at Caesar Creek, and the evidence was there, but our karma wasn’t.

 

So the trip was a bit disappointing. I thought I’d found better fossils in two hours my previous visit than over those two days. But that’s how it goes sometimes. You have to have perseverance, sharp eyes, and be in the right place. Beyond that it’s a matter of luck. Maybe I shouldn’t have been so intent on trilobites. I did find quite a few nice gastropods, and there were those cephalopods too. In the end it was certainly worthwhile visiting such a fossil-rich region, where any routine roadcut might hold the prospect of untold treasure.