Group members.
Individuals interested in undergraduate, graduate, or postdoc research opportunities in the Fischer Group at Caltech are urged to send a brief statement of background and interest. [recruitment]
Woodward W. Fischer [principal investigator]
Assistant Professor of Geobiology in Geological and Planetary Sciences. PhD Harvard University. BA Colorado College. I'm often called by my nickname, Woody. My research generally falls in the subdiscipline of Historical Geobiology—combining techniques from field geology, analytical chemistry, and biology— to understand and explore the relationships between of life and Earth surface environments through diverse and fundamental transitions in Earth history.
Kristin Bergmann
Graduate Student. BA Carleton College. I'm currently working with Woody Fischer, John Grotzinger and John Eiler to understand the connections between the nature of carbonate deposition and changes in Earth's past climate and seawater chemistry. I use a variety of techniques including clumped isotope geochemistry to probe the temperature and fluid composition of depositional and diagenetic carbonate-rich environments.
Renata Cummins
Graduate Student. BA Harvard University. I'm working with Woody to improve our understanding of the links between evolution and the environment through quantitative constraints on past climate change. I probe the stratigraphic record using several elemental and isotopic techniques, including clumped isotope paleothermometry. One major current goal is to better distinguish primary signals from postdepositional, diagenetic overprints by focussing on texture-specific relationships between different proxies for ancient climate and seawater composition.
Aya Gerpheide
Undergraduate Student. Occidental College. I am working on a project with the Fischer Group to better understand the timing and causes of the rise of atmospheric oxygen by studying the distribution of redox-sensitive detrital grains in early Paleoproterozoic sandstones. I employ a range of in situ techniques including light and electron microscopy, e-probe, and secondary ion mass spectrometry.
Jim Hemp
Agouron Postdoctoral Scholar. PhD University of Illinois at Urbana-Champaign. BS University of Minnesota. My current work is focused on the mechanics and evolution of high redox potential electron transfer chains in microbial metabolic pathways: aerobic respiration, denitrification, nitrification, and chlorophyll-based photosynthesis. I am working on projects with the Fischer Group at Caltech to better understand how cyanobacteria evolved the ability to split water during oxygenic photosynthesis by direct iteration of biochemical, genomic, and evolutionary observations and experiments with the paleoenvironmental record.
Jena Johnson
Graduate Student. BS Brown University. I'm currently working with Woody Fischer on a project to understand critical links in th evolution of the water oxidizing complex of photosystem II and the oxygenation of the atmosphere, by working to connect and test hypotheses developed from comparative biology and biochemistry with observations of the geologic record. I apply a range of isotopic and spectroscopic techniques, combined with observations from petrography and field geology, to Archean and Paleoproterozoic sedimentary successions.
Noah Planavsky
Postdoctoral Scholar. PhD University of California Riverside. BA Lawrence University. I study the connections between the evolution of Earth-system processes, biological innovation, and ecosystem change—foremost in Earth’s early history. My research integrates field, petrographic, and geochemical work. The protracted rise of oxygen over several billion years dramatically changed Earth’s surface environments. However, our current picture of Earth’s redox evolution is still painted with only broad strokes. A central theme of my research has been trying to piece together the history and effects of Earth’s oxygenation. With that end goal in mind, I am currently working on coupling paleoredox proxies in Precambrian sedimentary rocks, calibrating novel metal isotopes systems in modern aqueous systems, and untangling the distribution and diagenetic history of traces metals in sedimentary rocks.
Chris Reinhard
O.K. Earl Postdoctoral Scholar. PhD University of California Riverside. BA Kansas University. My research interest is in the chemical evolution of Earth’s oceans at broad spatiotemporal scales, and the coupling between this evolution and secular changes in atmospheric composition, biological innovation, and ecological complexity. Much of this work centers on the application of paleoproxies – using a combination of mineralogical patterns and major/trace element chemistry, often supplemented by traditional and non-traditional isotope systems, in order to reconstruct the chemical history of seawater. Current work includes geochemical study of Precambrian and Phanerozoic sedimentary rocks, proxy development and calibration in a range of modern marine and terrestrial aqueous environments, and work to explore and better understand the mechanistic links between electron flow and acid-base balance in seawater.
Sarah Slotznick
Graduate Student. SB Massachussets Institute of Technology. I’m working with Woody Fischer and Joe Kirschvink to understand Precambrian life, environments, and interactions between them. Currently, I am working on a project to understand the limitations and strengths of iron-based geochemical proxies used to understand the chemistry and redox conditions of early aqueous environments. I use a combination of rock and paleo-magnetic techniques, petrography, spectroscopy, and geochemical measurements with fieldwork in localities with well-characterized rocks from throughout the geologic record.
Alumni.
Seth Finnegan (former postdoc, now at UC Berkeley, Dept. of Integrative Biology)
Itay Halevy (former postdoc, now at Weizmann Institute, Dept. of Environmental Sciences)
Carina Lee (former staff, now at UCR)
Hanna Liu (former undergraduate, now at UCI School of Medicine)
Nikhita Poole (former high school student, now at Caltech)
Jon Wilson (former postdoc, now at Haverford College, Dept. of Biology)
Rebecca Zentmyer (former staff)
Past SURF and MURF students.
Aya Gerpheide (Oxy '14), Hanna Liu (Caltech '11), Haley Barnes (Caltech '12).
