“The spectacle of changing landscapes becomes an adventure into the geologic mystery of the past and the scenic beauty of the present.”
—Preston McGrain, Geologic Story of Kentucky
“It’s part of the story!” Jacoby exclaims, holding a dull gray rock above his head.
Jacoby is a student in my sedimentology and stratigraphy class. Thirty-two other students clamber about on the rocky slope in various states of confusion. They squint through their hand lenses and jot down observations in their water-proof notebooks. Hammers thud against the rock outcrop. A student’s foot sinks in the mud to above his ankle.
It’s geology field trip season.
The Earth System is complex and diverse. Textbooks and teaching samples can only go far. That’s why every spring undergraduate geology students leave their lecture halls in favor of the world’s classroom, to experience rocks in their natural habitat.
Dr. Jacalyn Wittmer Malinowski is fresh from a PhD at Virginia Tech. Now she is a geology instructor at the University of Illinois, and this is her class. I’m just the assistant.
She gathers the students with a shout. It’s story time. “What did you see?” she asks everyone.
“Rocks!” one student jests.
After some interrogation, another student confesses: “Packstone with brachiopods and bryozoans. A carbonate.”
“Good,” Dr. Wittmer replies. “What does that tell us about depositional environment?”
There are a few mumbles from the crowd: “Warm, shallow sea.”
“That’s right. We’re actually at the bottom of an ancient epicontinental sea right now.” Dr. Wittmer unrolls a map. It’s of the Commonwealth of Kentucky. But it’s not the kind of map you’d use to get around, unless perhaps you’re a geologist. To the uninitiated, the paper is more like a colorful Rorschach ink blot test, with its pastel bull’s-eyes and branching patterns, its purple swatches and mottled blues.
We’re at a road cut not far from Cincinnati, Ohio, near the rim of a circle of color centered on Lexington.
Kentucky has some of the largest and longest road cuts in the eastern U.S. Sometimes its as if highway engineers would rather blast through a hill than go around it. Kentucky State Geologist Jim Cobb tells me it’s because state highway planners limited the steepness of roads to make the going easier for coal trucks. Either way, the road cuts expose amazing geology that would normally be covered by soil and vegetation.
This weekend our class will cover 150 miles of highway and over 100 million years of geologic time.
“These rocks were deposited in the Late Ordovician,” Dr. Wittmer continues. “450 million years ago, when Kentucky was covered with water.” She points to the map. “This pink color where we are is the Kope Formation, which, as you’ve seen, is made up of cyclical packages of shale and fossiliferous packstone. These are some of the oldest and most pristine, unaltered sedimentary rocks in the United States.”
To us modern Earthlings, the Ordovician would appear absolutely alien. The continents were brown and barren. Almost all life was in the oceans. Reefs thrived, but they weren’t made of coral; instead, algae, sponges, and bryozoans dominated the sea floor. Animals familiar to us—clams, snails—mingled with strange species now diminished or extinct—trilobites, crinoids, blastoids, brachiopods. A few fish swam about, but they didn’t even have jaws. And evolution wouldn’t think up dinosaurs for another 200 million years.
After just a few minutes, it’s time to wrap up our discussion—there’s still a lot of geology to see. Dr. Wittmer makes sure to leave the students with a few unanswered questions, and we return to the road, an imposing convoy of university SUVs. Several children stop their game and stare as we drive by.
“How are you all doing?” I ask the students in my vehicle. “Feeling okay about the geology?”
They have a lot of questions:
“Are we going to see this many fossils the whole weekend?”
“What’s the deal with the cycles?”
“Was Nick serious about the plagiogranites and gabbros at this outcrop?”
I give them my usual answer: “You’ll find out.”
By the end of the trip, they’ll have figured out why the Kope Formation repeats itself—Milankovitch cycles, the same reason Illinois was buried by glacial sediment hundreds of millions of years later. But the story is bigger than that. They’ll see pulses of mud and sand carried by rivers to Kentucky’s ancient sea, evidence of the mountain building events that formed the Appalachians. They’ll see shaken up sediment left behind by ancient earthquakes. They’ll be both awed and overwhelmed by Dr. Carlton Brett, legendary paleontologist from University of Cincinnati, and his boundless knowledge. And they’ll put their hands on 50 million years of missing time at the Ordovician-Silurian boundary, where ancient erosion erased portions of Earth history like ripping pages right out of a book.
They’ll also watch me get an SUV stuck in a muddy ditch. They’ll get stuck themselves—in traffic, when they’ll play word games over the walkie-talkies. They’ll help prepare food for almost 40 hungry geologists using just a few camp stoves and some lanterns, and they’ll tell stories around the camp fire.
At some point, they’ll inevitably get annoyed at each other. But they’ll also allow their carefully constructed social barriers to crumble. Nicknames will be given, and inside jokes will be born. Though their humor will sometimes regress to that of a child, so will their ability to experience wonder at the simplest things, like stars on a clear night, or cold dew in the morning grass.
It’s Sunday evening now, and we’re just an hour’s drive from home. The students chatter in the back, sharing their favorite moments from the weekend. As I listen, I think back to my first geology trip:
It was to Long Beach Island, New Jersey, to study coastal processes. After a lecture on the beach, our professor turned and, without a word, waded into the bay. Most of the class stood awkwardly at the water’s edge, until the professor, now waist-deep, looked back to us and beckoned. “Come!” he yelled. “Be a sand grain!”
For some young geologists, once you get your feet wet, it’s hard not to just jump right in.