Sarah Slotznick, an assistant professor in the Department of Earth and Planetary Sciences, received the 2026 Takesi Nagata Early Career Award from the Geomagnetism, Paleomagnetism, and Electromagnetism (GPE) section of the American Geophysical Union (AGU), the world’s largest Earth and space science association.
Slotznick will be recognized at the AGU’s annual meeting, which will take place Dec. 7-11 in San Francisco.
“While my work is interdisciplinary, the GPE section of AGU has always been my scientific ‘home,’ the community I reach out to with questions and to share exciting new results,” she says. “It is such an honor to join the amazing section awardees who received the early-career award over the years. I look forward to continuing to apply magnetism to new fields while posing innovative questions!”
Slotznick, who heads the Dartmouth Magnetics Laboratory, studies the evolution of Earth’s surface environments and early life, and how the rock record preserves evidence of both. Her current projects take her to 1.5-billion-year-old rocks in western Montana and to Mongolia’s Gobi Desert, where the rocks hold a record of early mammals.
The Montana rocks contain fossils of early eukaryotes, the branch of life that includes animals and plants. “These are some of the earliest macrofossils, ones that can be seen with the naked eye,” she says, “but we only have casts of their forms without much detail.” The fossils turn up in some rock layers and not others, which could reflect where the organisms lived or just where conditions happened to preserve them. “The geologic context of where the fossils are found becomes key,” she says. That context is the focus of a collaborative project supported by the National Science Foundation.
The fossils sit in the Appekunny and Greyson formations, which had never had a comprehensive paleontological study before this project. The rocks are mostly on public lands that draw visitors from near and far, so the team also have worked to create educational resources and train local nature tourism guides to help the public learn about the evolution of life.
The project has since expanded to determine where Montana was on the globe when these organisms were alive. “Plate tectonics means that continents will move over time, and while the location of North America is one of the most well understood, there was conflicting data for this time period about the location,” Slotznick says.
Her way in was red beds, sedimentary rocks with minerals that can hold a magnetic record of where they formed. By studying red beds within and next to the fossil-bearing layers, Slotznick and Guarini PhD student Laurie Zielinski “have been able to resolve these contradictions,” she says. They’re now working on more red-bed formations to answer new questions the study raised.
‘Miraculously Recorded in the Rocks’
In Mongolia’s Gobi Desert, Slotznick studies a much younger slice of time: about 66 to 48 million years ago, just after the non-avian dinosaurs died out, when many modern mammal groups emerged. “Some of our richest fossil records of this time period come from the Gobi Desert,” she says.
Dating those fossils has proven challenging. The surrounding rock hasn’t been dated with precision, so researchers can’t easily tell whether fossils from different sites come from the same time, or how they compare with records elsewhere in the world. Slotznick is part of a collaborative NSF-supported project to date two of those fossil-rich rock units, the Naran Bulak and Gashato formations. One of the team’s four dating methods relies on magnetism.
A video from her team’s 2025 expedition shows the fieldwork in the Nemegt Basin of the western Gobi. In it, Michael Novacek, a curator at the American Museum of Natural History, explains that fossils can hint at how old a rock layer is, but a precise date has to come from the rock itself. A sharper timeline, he adds, could tell scientists more about how today’s mammal groups came to dominate after the dinosaurs.
One clue comes from small cores the team drills from the rock to measure its magnetism. “The Earth is enclosed in a magnetic field and that field flip flops,” Novacek says. “It reverses its pole from time to time. That is miraculously recorded in the rocks.”
Noah da Silva ’25, a post-baccalaureate scholar funded by Faculty of Arts and Sciences, worked on the Gobi project before heading to Oxford as a Rhodes Scholar. This year, post-baccalaureate scholar Elly Rectenwald is carrying the work forward.
Slotznick is also a recipient of a 2025 U.S. Department of Energy Early Career Research Program Award, a five-year, $900,000 grant to study the magnetic properties of cobalt-bearing minerals, which are mined for the cobalt used in electric vehicle batteries. That project grew out of unusual magnetic signals she found a decade ago in the 1.5-billion-year-old rocks of Montana.