The fossil hunter

Claire Conklin Sabel, a doctoral student in Penn’s History and Sociology of Science department, uncovers the findings of 18th-century amateur naturalist Elizabeth Thomas, along with artist and illustrator Alix Pentecost-Farren, who brings Thomas’ work to life.

shell fossil in hand
Sedimentary rock forms over time in layers of soft material like sand and silt. Where marine detritus falls to the ground, it is sometimes fossilized within the rock. Here, a bivalve shell is seen.

Summer afternoons in the Manuscripts Reading Room of the British Library are quiet with the rustling of turning pages and muffled thrust of chairs against carpet. The carpet is a muted gray green, set against the blonde wood and bottle green leather of the desks and chairs laid out in well-ordered rows across the room. It’s dim, with suffused light lingering in crossed recesses of the ceiling. Occasionally, sunlight filters from other, more open parts of the library, but mostly it doesn’t—leaving scholars undisturbed in their pursuits. 

Here sat Claire Conklin Sabel in 2019, a doctoral candidate in the History and Sociology of Science department in Penn’s School of Arts & Sciences who was researching gemstones and the history of coal. It was early on in her dissertation research and Sabel was pulling at loose threads. 

Interested in minerology and empire, she wondered when people started to think about how coal, this shiny rock that flakes at the touch, might be related to plants. Since coal was adopted for domestic uses before industrial ones in Britain, “I had this idea that women might be encountering coal in their homes,” Sabel says. 

As a science historian, Sabel is interested in what’s left out of textbooks—women’s contributions and “the hidden history of colonialism.” She was about to encounter primary source documents from Georgian England that pulled at both threads, offering a story that Sabel would continue to unravel over the next three years. 

The ‘fair sex’—women in science

There are 10 volumes of Emanuel Mendes da Costa’s documents in the British Library, an 18th-century Jewish naturalist whose family was involved in the gem trade. At random, Sabel picked the second tome and began flipping through, looking for references to gemstones, when she found the words “fair sex”—a period reference to women.

Da Costa was responding to a woman who had written to him about “having found some pieces of a fish in some coals... I search’d all the coal till I found a piece which has undoubtedly been the Head…” 

Sabel had come across the correspondence between the naturalist da Costa and Elizabeth Thomas, a genteel, middle-aged rector’s wife in the south of England. 

“That’s exactly what I was looking for,” Sabel thought. 

The correspondence came alive for her. The letters were detailed, descriptive, and passionate, she says. “This is someone with no scientific training, who had engaged in this relationship with a professional naturalist in 18th-century London.” 

Animating the world of Elizabeth Thomas, fossil hunter

Thomas didn’t draw pictures of her fossils, but described them to da Costa in intimate detail, going back and forth with him about whether a scale pattern on a fragment of fossilized coal was the imprint of a pinecone (da Costa’s description) or the scales of salty fish flesh (Thomas’ theory).

Alix and Claire with a northleach fossil
Pentecost-Farren (right) and Sabel (left) with a Clypeus ploti fossil found in Northleach. Clypeus ploti, a relative of the sea urchin, is locally known as a “pound-stone” because they typically weigh roughly one pound and were used by dairy workers to measure milk and butter. (Image: Courtesy of Julia Owen)

For the record, da Costa was right, but most of the fossils surrounding Thomas were marine, embedded in sedimentary limestone that archived centuries of sloughed-off skin and shell. “She sees a fish; other people see a plant,” Sabel says. She tried to envision this conundrum. 

For Sabel, it was clear that these writings needed to be interpreted and illustrated, and for that, she turned to Alix Pentecost-Farren

“I have always loved her work, which is about the human engagement with the natural world,” says Sabel. Both women had a mutual interest in the history of science and this project seemed like a natural point for collaboration. Sabel and Pentecost-Farren applied for and received a 2021 grant offered by The Sachs Program for Arts Innovation, which supports creative projects in the arts and humanities at Penn. This enabled the pair to work in tandem.

“I was immediately interested,” Pentecost-Farren says, noting that Thomas came across as driven and emboldened. "She was passionate and connected [the fossils] to her spirituality. It was fascinating.” 

Both women slip in and out of tenses when talking about Thomas. In her world, both the past and present converge, coming alive through a series of letters that, to Sabel and Pentecost-Farren, felt urgent, vital. There’s an intimacy there; da Costa is da Costa, but Elizabeth Thomas is always simply “Elizabeth,” as one would refer to a friend. 

“She was an inspiring character,” Pentecost-Farren says. She “felt really alive, even though she was from such a different time.”

animated gif of fossils
Pentecost-Farren’s animation of fossil forms.

The pair selected a series of scenes that each captured a piece of Thomas’ experience during her fossil hunting years. “We just kind of have this glimpse,” of Thomas and her life, says Pentecost-Farren. Sabel wrote accompanying essays that “introduce us to her world,” each one drawing on a moment that Thomas describes in the letters.

Pentecost-Farren opted to do animated GIFs as well as still illustrations of Thomas and her fossil finds, “to kind of bring them further into life, so they’re kind of breathing in a way,” Pentecost-Farren explains. “The images that we select are all trying to show her experience of discovery.” She and Sabel thought of the illustrated moments as “facets,” “a way for us to tell her story in an approachable way, without kind of trying to squeeze into a traditional narrative.”

Empire and ambition

Born around 1716 to “a quite well-off family in Kent,” Thomas was from southeast England and stayed in the region for much of her known life, although her family ranged widely, Sabel says. Thomas’ birth family, the Amhersts, were known for their military and naval prowess and their exploits touch on “some of the most explosive and violent moments of British imperial expansion,” Sabel says. 

Amherst, Massachusetts, was named for Jeffrey Amherst, Thomas’ second-oldest and most decorated brother. Amherst served as a general during the Seven Years’ War; Thomas writes that even those in her small town of Northleach would toast his name. 

Amherst is infamous as well: As the commander-in-chief of British forces in North America, he encouraged his men to distribute blankets infected with smallpox amongst Indigenous Lenape, Shawnee, and Haudenosaunee populations attacking the British forces at Fort Pitt, now Pittsburgh, during Pontiac’s War in 1763. 

This, Sabel says, is “among the most direct evidence of British genocidal intent in North America, though Amherst was far from the only proponent of this practice.” 

By the start of her correspondence with da Costa in 1757, Thomas had her brothers sending fossils from abroad as they traveled between England, South Asia, and colonies in the Caribbean, and North American, courtesy of Her Majesty’s navy.

I have hitherto considered my Love of Fossils as a sort of wild Passion, without any manner of use, but you have convinced me of it’s being a very delightful science. 18th-century amateur naturalist Elizabeth Thomas

The word “amateur” came into being during Thomas’ time, derived from the French for “one who loves.” An amateur is one who cultivates—but does not profit from—an area of study, someone who teeters on the boundary between expert and outsider.

There were many such amateurs during the 18th and 19th centuries, people who pursued the hallowed halls of art or the burgeoning field of science. Many of these interests—like Thomas’—were supported with family wealth and endeavors of empire. Most public positions were held by men; few women ventured into the amateur realm. 

A big part of the story is that Thomas was a woman, Sabel says, and women did not have access to academic spaces in the 18th century. Even though it became fashionable for middle- and upper-class women to cultivate scientific interests, “it was always treated as something remarkable and exceptional,” Sabel says, noting that Thomas was more unusual still in that she did much of her own fieldwork.

“Her sheer enthusiasm is driving this interest,” Sabel says. “She kicked her husband out of his study so that she could have it for her fossils. To me, that felt like a historical event.”

Field work

“I have hitherto considered my Love of Fossils as a sort of wild Passion, without any manner of use,” Thomas wrote to da Costa, “but you have convinced me of it’s being a very delightful science.”

Da Costa encouraged his interlocutor, guiding her scientific interest. He asked her to send him as many interesting specimens as possible, telling Thomas that her work was not just useful to him but to the cause of science. He told her what to look for and how to create a record.

Illustration of a person holding stones by a stone wall.
Pentecost-Farren illustrated Thomas searching for fossils in the walls on her walk. Many of the walls in Northleach exist just as they did in Thomas’ time, built using drystack construction and stone from local quarries.

“I really see her as contributing to the popularization of, and public engagement with, natural history, which was necessary to develop the careers of people like da Costa,” Sabel says. This broader social validation made it possible for science to go from a hobbyist’s pastime to a professional career, she says.

Thomas outlined her lines of inquiry and research, explaining her theories. Noticing how the nearby springs were “petrifying, or rather encrusting everything that lies in their walls,” Thomas placed a toadstool in the water to see what would happen, if she could replicate this process.

She was observant, curious, and relentlessly fascinated by minutia. While driven by circumstance to dwell in a particular locale during a particular time, rather than chafing against her bonds, Thomas used them to dictate the boundaries from which her intellect could expand.

In 1751, at the age of 37, Thomas married a pastor who became the rector of Northleach, a small town in the Cotswolds, a famously idyllic corner of rural England. It’s Downton Abbey territory, where quaint villages built of golden stone line meandering rivers. Thomas would study these walls on her walks, says Sabel, “continually picking out of the stones and admiring them with a magnifying glass,” as she wrote to da Costa.

“Even our walls afford me amusement” she wrote to da Costa, “and are built with a sort of stone that seems compos’d of seas and full of shells.” 

Walking in Thomas’ steps in the Cotswolds

Sabel and Pentecost-Farren got a second grant, the GAPSA-Provost Fellowship for Interdisciplinary Innovation, to travel to England in April 2022, spending a week amongst archives in London before going to the Cotswolds to retrace Thomas’ life and steps. 

It was spring, lambing season. The Cotswolds, Sabel says, are “mostly sheep and small stone villages, more or less intact since Thomas’ time. Northleach, where Thomas lived, has been particularly well-preserved, not just since the 18th century, but since its medieval origins.”

Sabel and Pentecost-Farren walked along public foot paths, talking with local historians, visiting the church where Thomas’ husband pastored his flock, looking at maps and property lines. 

“You’re constantly looking for traces of what was, trying to understand how this would have looked in a different time,” says Pentecost-Farren, who was entranced with the patterns and patina of use and disuse, thinking about how to incorporate the passage of time into her illustrations.

Elizabeth and John Thomas burial location
Alix Pentecost-Farren sketching in the graveyard of Church of St Bartholomew, Notgrove, where Elizabeth Thomas and her husband John are buried.

“Lots of things had changed about the use of the land, but it was really exciting once we found the kind of fossils she had described,” says Sabel. 

The pair got a local tip to look for fossils in the mole hills. Natural diggers, moles create little mounds of freshly turned earth, where Sabel and Pentecost-Farren found shells and fossils. 

“We experienced it as she would have, says Pentecost-Farren. Northleach was “extremely quiet, even now,” she says. “Just thinking about [Thomas] and how she just had such an active mind and was living in a very slow-paced, secluded area, it was not surprising to me that she started noticing anything she could around herself.”

Thomas’ correspondence with da Costa continued for more than three years until 1760, when it ends for reasons that are unclear, Sabel says. Thomas, who was then in her mid-40s, adopted a child during this time and authored a few published poems, but for the most part, remains opaque. 

“What the rest of her life was like and what happened her before this period of intense fossil correspondence still remains to be accessed,” Sabel says.

Sabel and Pentecost-Farren are finishing up their project, which they hope to find an outlet for by the end of the year. Sabel is writing an academic article and collaborating with Pentecost-Farren on a longform illustrated essay about their trip, Thomas’ life, and what the history of science “can tell us about the way that lay people participate and influence scientific culture,” she says. 

Thomas represents a larger group of “many curious individuals who took the time to explore their own curiosity,” Sabel says. She’s a woman whose exploration is part of the history of science, Sabel continues, and “it’s just very rare that we have records of what [these lay people] were doing, when they were doing it, and what it felt like for them.” 

The correspondence between Thomas and da Costa “provides this very unusual window into the kind of emotional, psychological, social experience of getting involved in science as a hobby,” Sabel says. 

In modern science, “everything has to go through discourse and experts in order to become a legitimate form of participation,” Sabel says. What’s lost is accessibility, she says, along with “play and delight and creativity and freedom to interpret and challenge scientific authority.” Thomas’ words provide a counterpoint, she says. “I think it's just a welcome invitation for us today.”

Sometimes discoveries are made within the white-clad walls of a laboratory, and sometimes in a bubbling stream or the golden walls of sunbaked stone, leading to one question, and then another. 

Person standing in a large green field.
(Homepage photo) Locals advised Sabel and Pentecost-Farren (seen here) to look in this field between Hampnett and Northleach, where the pair found several fossilized sea urchins.