Students interpret Earth as text in Geophysical Sciences field methods course

Chelsea Leu, a third-year in geophysical sciences, spent spring break learning scientific field methods at San Salvador in the Bahamas with a group of other University of Chicago students and faculty members. The trip followed weekly seminars that met during the Winter Quarter. The News Office commissioned her to write this story about her experience.

Next to a small lake on an island in the Bahamas, Sue Kidwell directs three undergraduate students on the proper way to take a sediment core, a cylindrical section of mud and sand. This is a delicate operation and all are ankle-deep in rust-colored, gelatinous mud. This mud is colonized by microbes, which produce the acrid smell of sulfur that permeates the air around them.

The three students—Hannah Diamond-Lowe, Meg Stuckey, and Rachel Atlas—trudge with some difficulty across the lake and survey the ground for an ideal spot. “We want an undisturbed mat,” Sue advises them. The rest of our 20-odd group are ranged on the hillside, watching. They successfully locate a spot, and Hannah pushes the large plastic tube into the ground easily, prompting an “Excellent! Nice technique!” from Sue. The three measure the interior and exterior lengths of the exposed pipe, and then seal off the top of the tube with a rubber stopper.


“And now, Hannah,” Sue directs, “remember you want to do a fairly broad rotation; you want to break off the bottom of your column of mud.” Hannah complies. “Now, pull very gently and see if it looks like the inside is going to come up with it.” There is a suspenseful pause as the three women check. Meg answers in the affirmative.

“Yes!” Sue jumps and claps her hands. “Yes! Beautiful technique. But be ready to put your hand right underneath, because it won’t stay there.” Hannah pulls up on the handle, and there is a loud, flatulent report as the core squelches free from the sediment. “Beautiful! Look at that!” Sue cries. We break out into applause.

As a third-year geophysical sciences major, I was lucky enough to enroll in GEOS 29002: Field Course in Modern and Ancient Environments, this past quarter. The class met for weekly seminars before culminating in a trip to San Salvador in the Bahamas over spring break. There were 28 in our party: 16 undergraduates, nine graduate students, two faculty members and a postdoctoral scientist whose research interests mainly drew from geology, biology, and the intersection of the two.

Gerace Research Centre

The island of San Salvador is a mere 12 miles wide, and remote — it is the location where Columbus allegedly made landfall in 1492. Our destination, however, was the Gerace Research Centre on the north side of the island, which plays host to more than a thousand researchers per year. UChicago enjoys a long-standing relationship with the GRC. Its current executive director is Tom Rothfus, PhD’05, an alumnus of the geophysical sciences department.


The purpose of this field course, ostensibly, was to allow budding geologists and biologists to gain experience with field methods. Indeed, we learned how to use geologists’ compasses to measure the direction of ancient currents, how to describe a stratigraphic section, and how to take and analyze sediment cores. But beyond field techniques, our teachers taught us how to use our observations to make sense of the environments around us.

Guiding us in this process were Sue Kidwell, the William Rainey Harper Professor in Geophysical Sciences, and Michael LaBarbera, professor in organismal biology and anatomy, affectionately known as “LaB.” This is the fourth time Sue has led this trip in the past 10 years, but somehow she seemed boundlessly energized by everything we saw. In the field, she would gesture expressively to illustrate concepts like aeolian cross-bedding, and we scrambled over boulders trying to keep up with her blazing pace.

We also worked alongside the graduate students, who proved to be enthusiastic, skilled, and good-humored individuals who shared their expertise with us. Because our group was constantly at close quarters, it was a simple matter to gain one-on-one time with these experts in the field, in lab, and over meals, opportunities that we seized.

Out in the field, we were surrounded by a wealth of unique geology and biology, none of which seemed to be lost on our teachers. At Bamboo Point beach, LaB spotted two frigate birds soaring gracefully in concert above us, and informed us that their relatively large wings allow them to glide on warm, rising air with barely a flap of their wings.

We waded in Pigeon Creek, a shallow inlet, to investigate the sand mounds created by burrowing ghost shrimp, and stepped knee-deep in opaque Storr’s Lake to find stromatolites, craggy microbial growths that are rare today, but dotted the Earth’s surface more than three billion years ago.

In lab every evening, we’d report back on the unique organisms we had spotted while snorkeling in San Salvador’s clear waters: an elusive sea turtle, sea urchins the size of softballs, a beached Portuguese man o’ war. During one such session, a rat skittered into the room. Instead of recoiling, we all craned our necks to get a better look at the mammal, rare on the island.  

‘Be true to your rocks’

Over the course of the trip, it became clear that we could learn from nearly everything we found. Sue advised us to constantly ask ourselves questions, to form hypotheses about our environment, and then look for evidence in the field to support or reject these conclusions. “Describe what you see,” she told us, “and be true to your rocks.”

One day, we measured and described layers of fossilized coral in the preserved remnants of a reef that is hundreds of thousands of years old. These data were purely descriptive, but they could be interpreted to form a coherent narrative, as we discovered that evening in lab. Working with the multicolored diagrams we had drawn on the chalkboard, Sue led us through a reconstruction of the reef’s history. She described a particularly chaotic section of rock, a jumbled collection of fragmented staghorn corals and clamshells, then paused.

“Are the hairs rising on the back of your neck?” she asked, dramatically. These fragments, she suggested, were the debris of past storms that had pummeled the reef and wreaked havoc on its inhabitants. The story wasn’t clear, but we learned something about the reef’s past: its environment was a dynamic, shifting one. The world was full of stories, and we could discover them if we learned to understand the signs.

Though my days in San Salvador were just as rigorous as they are at Chicago, and my classmates and teachers just as intellectually engaged, the way I was learning felt fundamentally different. We were practicing a different skill set: using our senses to gain a better understanding of the environment. The entire world was our classroom. A rock was no longer just a rock but almost a sort of text, to be scrutinized and analyzed for deeper truths. In San Salvador, “taking the core” meant something entirely different from its usual UChicago meaning.