Focus on the Faculty: Sally Walker

Sally E. Walker, the inaugural Shellebarger Professor in Geology in the Franklin College of Arts and Sciences, gives students field research experiences through which they propose hypotheses, collect and analyze data, and communicate their findings:

What are your favorite courses and why?

My favorite courses concern connections: how evolution of life on Earth affected geological and atmospheric processes and vice versa. The naturalist John Muir remarked, “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” The birth of elements emanating from the big bang and supernova explosions are those same elements that form life on Earth. When photosynthesis evolved, life forever changed our hot, acidic atmosphere to an oxygenated one, contributing to our first ice age 2.2 billion years ago. Increase in biotic oxygen led to larger and more complex life and also new minerals/ores. When biocarbon was buried, it became coal or petroleum, cooling Earth; but in the last 200 years, humans have burned those fossil fuels, leading to hotter climates, higher sea levels, and major humanitarian/economic crises unless sustainable practices are achieved. After all, we are hitched to everything else.

How do you describe the scope and impact of your research or scholarship to people outside of your field?

I work in fossil forensics: I am curious about how clams and snails store environmental information in their carbonate shells and how that information can be used to reconstruct climates, ecological interactions and environments of the past. With colleagues, I helped start the longest running field experiment concerning biotic carbonate from shelf to deep-sea environments in the Gulf of Mexico and Bahamas. We found that deep-sea ecological processes that affect shell preservation are just as complex as those in shallower water, against prevailing ideas at the time. We also successfully cracked the code on the stable isotopes preserved in the shell of Stephen Jay Gould’s favorite Bahamian land snail, Cerion, which revealed seasonal cyclicity when it was thought not to occur. Currently, we hope to unlock the climatic record archived in modern and fossil shells of the Antarctic scallop to reveal past sea-ice fluctuations in the Cenozoic record.

One of the best on any campus, Dr. Walker inspires our students as a holistic example of the scientist in full. Read more about her Shellebarger professorship here.