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Dr. Ben Johnson
he/him/his Assistant Professor NSF Postdoc, University of Colorado Boulder: 2017-2019 PhD, University of Victoria: 2012 MS, University of Utah: 2009 BS, University of Puget Sound: 2006 Ben is a geologist and geochemist with broad interests that span Earth History and Earth System Science. He uses a variety of rock archives, including chemical sediments, glacial tills, and igneous rocks as records of the interactions between life, the oceans, the atmosphere, and the solid Earth over deep time. He uses field work, analytical and isotope geochemistry, and numerical modeling to investigate deep time questions about Earth history. He is also interested in astrobiology and planetary science! . Click here to visit my Google Scholar page. Click here to visit my Research Gate profile. Click here for my CV. 
John Herring
He/him/his PhD candidate John graduated from Purdue University in May 2023 with a double B.S. in Geology and Geophysics and Planetary Science, and is a 3rd-year Ph.D. candidate under Dr. Ben Johnson at Iowa State University. As a Ph.D. student, John studies the evolution of Earth’s biogeochemical nitrogen cycle over deep time through computational modeling. In particular, he focuses on reconstructing global emissions of nitrous oxide (a greenhouse gas which depletes the ozone layer) to resolve its effects on “hothouse” climate and atmospheric chemistry over the past 550 million years. John also studies changes in atmospheric pressure due to biological nitrogen sequestration into the solid Earth over geologic timescales, with potential impacts on past climate stability. More broadly, he is interested in using computational tools in biogeochemistry and geobiology to investigate topics in Earth history and planetary science. John is also a teaching assistant for the class Geology for Engineers and Environmental Scientists (GEOL 2010) at Iowa State University. 
Brielle Martin
She/her/hers MS Student Brielle graduated from Bowdoin College in May 2024 with a coordinate major in Earth and Oceanographic Science and Environmental Studies. She is currently working towards her master’s under Dr. Ben Johnson. Brielle is interested in using geochemistry to interpret earth’s past. Her research focuses on expanding existing understandings of the Neoproterozoic nitrogen cycle by determining the depositional environments of ancient sediments with a multi-geochemical proxy approach. 
Kaden Neddermeyer
He/him/his Undergraduate researcher Kaden Neddermeyer is an undergraduate researcher pursuing a B.S. in Geology and a B.A. in Computer Science. He is currently working with Dr. Ben Johnson on a project involving numerical modeling of O isotopes, which can be used to draw conclusions about continental emergence or paleoaltitudes. |
Alexandra Grajales
she/her/hers PhD candidate Alex received her B.S. in Geology and a minor in Science Education from the University of Puerto Rico- Mayaguez in 2021. Alex is interested in studying the evolution of atmospheric conditions through time using biogeochemistry and paleobotany. She is a 4th year PhD candidate with Dr. Ben Johnson. Her research involves measuring C and N in fossil and modern leaves to measure ecosystem and plant type variability through the geologic record. She is currently at the Smithsonian National Museum of Natural History completing a yearlong fellowship with Dr. Scott Wing investigating the decay rate of leaf tissue of N-fixing plants before fossilization as a mechanism to understand changes in C and N dynamics. 
Erin Bell
She/her/hers MS Student Erin completed her B.S. in Geology at Texas Tech University in 2026. She is currently pursuing a Master’s degree in Geology at Iowa State, working with Dr. Ben Johnson. Erin’s research uses the igneous rock archive to reconstruct deep Earth history and explore qualities that make our planet so unique. Specifically, she studies oxygen isotope records preserved in altered oceanic crust to better constrain the timing of continental emergence. 
Jonah Karpf
He/him MS Student Jonah received his B.S. in Chemistry with a minor in Geology from Florida State University in April of 2026. He is currently pursuing a M.S. in Geology under the direction of Dr. Ben Johnson. Jonah is interested in research that utilizes analytical geochemistry to reconstruct past Eart conditions. His current research is concerned with measuring the oxygen isotope signatures of altered oceanic crust to measure the emergence of Earth’s continents over long time spans. 
Catie Purdue
She/her/hers Undergraduate researcher Catie, class of 2027, is studying for her B.S. in Geology with minors in Biology and Anthropology. She is currently assisting as an undergraduate researcher under Dr. Ben Johnson, and is working on a GeoURG project involving leaf decomposition and isotope alteration. 
Nick Bellich
He/him/his Undergraduate researcher Nick is an undergraduate researcher pursuing a B.S. in Geology with a minor in Biology (and Paleontology!). He works under Ben and Alex in the lab studying carbon and nitrogen isotope concentrations in fossil plants from the Eocene, as well as extant plant specimens. The goal is to reconstruct the paleoclimate of the early Eocene by studying the relationships between and atmospheric carbon dioxide concentration isotope ratios within plants. |
Former members
Samuel Duncanson
He/him/his
PhD 2026
M.S., Geological Sciences, University of Minnesota Duluth
B.S., Geology, University of Saint Thomas
Sam studies the nitrogen values of glacial sediments throughout Earth History. He conducts this research with geochemistry, sedimentology, and mineralogy in mind.
He/him/his
PhD 2026
M.S., Geological Sciences, University of Minnesota Duluth
B.S., Geology, University of Saint Thomas
Sam studies the nitrogen values of glacial sediments throughout Earth History. He conducts this research with geochemistry, sedimentology, and mineralogy in mind.
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Dana Mineart, MS, 2021-2023
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Kate Preibish, undergraduate researcher (2021-2023)
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Justin Glenn, undergraduate researcher
(2021) |
Ben Boesen, undergraduate researcher (2020-2021)
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Haley Bix, undergraduate researcher
(Spring 2021) |
Emily Meinert, undergraduate researcher
(Fall 2020) |