I’m delighted to present Dr. Jill Marshall as the 2018 recipient of the Luna B. Leopold Award. Jill is a relentless scholar and fearless scientist boasting substantial contributions in soil geomorphology, paleoclimate and landscape evolution, cosmogenic nuclide modeling, topographic analysis, and mechanics of biota in the critical zone. From the outset of her academic career, Dr. Marshall has demonstrated her mastery of both big-picture questions that drive our discipline and methodological details paramount to her research endeavors. Jill thrives on collaboration. Those of us fortunate enough to have been drawn into her orbit have benefited tremendously from her conceptual intuition and her ability to identify study areas and methods to test new and compelling hypotheses. Jill is highly deserving of the Leopold Award, as, like Luna, she refuses to recognize potential barriers that might otherwise separate theoretical work and field observations.
For her M.S. degree, Jill mined soil science data to demonstrate that climate can explain soil clast size distributions that are key to hillslope–channel coupling. In her Ph.D., Jill challenged the notion of steady erosion in unglaciated landscapes and used a 50-kiloyear sedimentary archive to show strong coupling between paleoenvironmental trends and paleoerosion rates. By combining paleoclimate simulations with a frost weathering model, she highlighted the surprising extent of periglacial processes in unglaciated landscapes. More recently, Dr. Marshall is tackling the problem of how tree roots penetrate, fracture, and extricate bedrock in near-surface environments. This process is illustrated in countless textbook cartoons but has been essentially untouched in the scientific literature, until now. In summary, Jill is a shining example of the interdisciplinary and deeply skilled geoscientist that funding agencies and research institutions seek to train and employ. I’m eager to see her next suite of discoveries and the research directions that she defines for our field.
—Josh Roering, University of Oregon, Eugene
Thank you for the wonderful citation. I am profoundly honored to receive the Luna B. Leopold Award. It’s a testament to the extended science community that I’ve had the privilege of learning from. Together we’ve tested ideas that are bigger than any one of us.
I came to geomorphology sideways, starting at community colleges while working full-time. Hired at an environmental agency, I grappled with melding information from physical and biological systems across scales. While growing into river and watershed science, I began to intersect with Bill Dietrich and Tom Dunne. Their unstinting interest in my ideas and willingness to engage my curiosity sparked a desire to learn quantitative science, leading to a journey from theory to the field and back again. Importantly, I learned that good ideas should, and could, matter more than pedigree.
Leonard Sklar entrained me in the quest to tease apart controls on grain size distributions produced by hillslope processes. As we dug pits and I dug into decades of soil data, I stood intellectually and literally at the intersection of climate, tectonics, lithology, and soil production processes. I am deeply grateful to Leonard for setting no limits on how to approach a mostly unexplored problem. For my Ph.D., I traveled to the seemingly well characterized Oregon Coast Range, where Josh Roering encouraged roaming among topics and tools while modeling broad interests, kindness, and humility. As I roamed, I absorbed frameworks from disparate disciplines, ranging from paleoclimatology to forest ecology. This has served me well as I continue to explore the role of climate and rock properties on biotic and abiotic mechanisms that shape our Earth. I thank Bob Anderson, Bill Dietrich, and the Critical Zone Observatory community for invigorating postdoc mentoring; my Ph.D. lab mates; and those involved in nominating me, led by Jane Willenbring and Nicole Gasperini.
—Jill Marshall, University of Arkansas, Fayetteville