Division Management Board

Chair (2025-2026)

Noah McLean is an Associate Professor of Geology at the University of Kansas. He is a statistically inclined geochronologist who specializes in U-Pb geochronology, often integrating other U decay products. His research interests include magmatic processes in large igneous systems and telling time in the sedimentary record, as well as developing cyberinsfrastructure for the geochronology and isotope geochemistry community. He has also been a part of the EARTHTIME community that contributed method development and mentorship efforts.
Contact: noahmc@ku.edu

First Vice Chair

John Cottle is a Professor of Geology at the University of California Santa Barbara. He uses a range of field, petrologic, and geochronologic methods to identify and constrain the temporal and. spatial scale of processes that serve to modify and/or produce new continental crust. He is particularly interested in better understanding the metamorphic, magmatic, and tectonic evolution of the Himalaya, Antarctica, and New Zealand. He also develops novel laser ablation analytical techniques to measure the ages and compositions of minerals at the micron scale.

Contact: cottle@geol.ucsb.edu

Second Vice Chair

Mauricio Ibañez-Mejia is an Associate Professor of Geology at the University of Arizona. His main interests are in the application of geochemical methods, particularly isotope geochemistry, to solid Earth processes. Mauricio's research combines the use of radiogenic isotope systems such as U-Pb, Sm-Nd, and Lu-Hf to determine time and rates, and geochemical tracers such as elemental abundances and isotopic compositions (radiogenic and stable) to understand petrologic and tectonic processes.

Contact: ibanezm@arizona.edu

Secretary

Tiffany Rivera is an Assistant Professor in the Department of Geological Sciences at the University of Missouri-Columbia. Her research focuses on geochemistry and geochronology of bimodal volcanic fields. She integrates zircon petrochronology with ⁴⁰Ar/³⁹Ar geochronology to understand the timescales of magmatic evolution and petrologic relationships amongst erupted lavas. Tiffany has worked on the Yellowstone volcanic field to understand the connection between super-eruptions and small-volume lavas. Her current projects are focused on the Black Rock Desert of central Utah. Contact: trivera@missouri.edu

Treasurer

Elizabeth Niespolo is an Assistant Professor in the Department of Geosciences at Princeton University. She uses geochronology, stable isotopes, and field observations to address questions regarding past climate, terrestrial paleoenvironmental reconstruction, and human evolution. She is setting up a U-series geochronology lab at Princeton, including in situ multi-element and isotopic characterization of samples using laser ablation. Her research focuses on developing and refining chronometers (40Ar/39Ar, U-series, 14C) to more meaningfully date records of Earth history, paleoclimate, evolution, and the prehistoric archaeological record.
Contact: niespolo@princeton.edu

Diversity and Outreach Coordinator

Robin Trayler is an early career researcher and the Director of the Stable Isotope Ecosystem Laboratory at the University of California, Merced. Broadly, his research focuses on the interplay between climate and ecology over geologic timescales. He uses a variety of tools including U-Pb and radiocarbon geochronology, astrochronology, and stable isotope geochemistry. He integrates these disparate data using Bayesian timescale modeling to elucidate the rate and tempo of climatic and ecological change. Currently, Robin is working on developing joint inversions of astrochronology and radioisotope geochronology in deep time, and also untangling the chronology of tar seep fossils sites in California.
Contact: rtrayler@ucmerced.edu

Historian

Leah Morgan is a geochronologist in the ⁴⁰Ar/³⁹Ar geochronology lab at the USGS in Denver, Colorado, working on a range of applications and method development issues in ⁴⁰Ar/³⁹Ar geochronology. Applications have largely focused on questions in paleoanthropology, geologic mapping, and ore deposits. Method development projects include developing metrologically traceable systems for measuring absolute quantities of ⁴⁰Ar and ⁴⁰K, and the design of a mobile neutron source for the future in situ deployment of ⁴⁰Ar/³⁹Ar capabilities on planetary surfaces. Leah was the founding chair of the Geochronology Division (2018-2019).
Contact: leahetgmorgan@gmail.com

Student Representative

Emma Hughes is a master's student at the University of South Florida. Emma graduated from Cornell College in Mount Vernon, Iowa, with a degree in Geology in the spring of 2024. During her undergraduate studies, she conducted research on speleothems using stable isotopes and U-series dating for paleoclimate reconstructions with the support of Dr. Rhawn Denniston. In addition she worked with the Iowa Geological Survey on sedimentary archival projects. Now, as a graduate student at the University of South Florida, she is researching past sea-levels using cave-based proxy data under the guidance of Dr. Bogdan P. Onac. Her research focuses on the Caribbean Sea.

Contact: ekhughes@usf.edu

Student Representative

Jacqueline Giblin is a fifth-year PhD student at Arizona State University (ASU). Her research focuses on orogenic evolution and long-term tectonic processes, utilizing multi-mineral geochronology and thermochronology methods, including ⁴⁰Ar/³⁹Ar, (U-Th)/He, and U-Pb chronometers. She also contributes to geochronology projects in sedimentary provenance and young volcanism. Passionate about education and diversity in the geosciences, Jackie is currently leading efforts to redesign ASU’s undergraduate introductory geology lab course to foster inclusivity and engagement.

Contact: jlgiblin@asu.edu

Past Chair (2024-2025)

Mark Schmitz is Distinguished Professor of Geochemistry at Boise State University, Idaho, USA, and has extensive research interests in the development and application of radiogenic isotope geochemistry and high-precision U-Pb geochronology to problems of Earth systems evolution. He has been an active member of the EARTHTIME community and co-editor and author for the Geologic Time Scale 2012 and 2020. He is the founder and director of the Isotope Geology Laboratory.
Contact: markschmitz@boisestate.edu

Outgoing Past Chair (2023-2024)

Brad Rosenheim is an Associate Professor at the College of Marine Science at the University of South Florida. He specializes in 14C geochronology, with experience in U-series dating as well. His research focus is global change during the late Pleistocene and through the Holocene, driven by society’s need for a natural climate change baseline for comparison to human-driven climate change. Dr. Rosenheim developed the Ramped PyrOx (pyrolysis and oxidation) technique for 14C analysis and has applied it to provide insight to a wide range of sub-disciplines of the geoscience – geochronology, pollution mapping, and biogeochemistry of rivers and the coastal zone.
Contact: brosenheim@usf.edu

Outgoing Student Representative

Karissa Vermillion is a 2nd year PhD student at the University of Houston (UH) who works at the UH Helium Laboratory. As a geochronologist, Karissa seeks to better understand tectonic processes and landscape evolution utilizing thermochronology and geochemistry of common minerals (e.g., zircon and apatite) from not just basement exposures, but also detrital sands and clasts. This novel technique allows Karissa to better reconstruct the tectonic history of a region, even when the source basement is partially to completely eroded.
Contact: kvermill@cougarnet.uh.edu