SIPERG Members

Dr. Alan Wanamaker (he/him/his) — Professor and Director (currently on assignment to the National Science Foundation as a Program Director in the Marine Geology and Geophysics Program, Division of Ocean Sciences).

Welcome to the SIPERG. I am a broadly trained geoscientist who is interested in using geochemical and sclerochronological techniques to document (and better understand) changes in Earth’s climate and ecosystems through time. I particularly enjoy developing and using proxy archives to unravel past environments. We have several exciting research projects that are underway, so if you would like to know more about us, and our research group, please contact me.

Suzanne Ankerstjerne — Lab Manager and Research Scientist

I am the lab manager for the Stable Isotope Laboratory in the department of Geological and Atmospheric Sciences. My duties include coordinating and scheduling activities within the lab and maintaining the resources necessary to complete quality stable isotope measurements. I enjoy working with students, Iowa State faculty, and other scientists to obtain high quality data.

Dr. Diana Thatcher (she/her/hers) —Research Scientist






My research supports efforts on a Gulf of Maine project (Collaborative Research: Using multi-proxy paleo data to constrain natural and anthropogenic hydrographic variability in the Gulf of Maine System over the last 250 years) and other paleoclimate related projects using speleothems, clams, and climate model output.


Thomas Getz (they/he) — MS Student














I received my BS in Geology from Iowa State University. My MS project involves investigating hyperthermal events during the Paleocene and Eocene using a combination of stable isotope geochemistry in carbonate nodules, sedimentological analyses, and mapping in Wyoming and the surrounding region.


Current Undergraduate Researchers and Laboratory Assistants

Amanda Hauser (she/her)













I am in the Environmental Science and the Climate Science programs in the College of Liberal Arts and Sciences. My research entails using sclerochronology techniques on clam shells in the coastal Gulf of Maine.


Graduate Students

Heeyeon Sun, MS Geology May 2023 – “Using clam-based stable isotopes and growth histories to reconstruct the temporal oceanographic variability in the Southern Mid-Atlantic bight over the last 185 years.

Alex Walton, MS Environmental Science May 2023- “Using the Growth and Geochemical Signatures of Arctica islandica from Jonesport, ME, USA to Document Environmental and Oceanic Variability of the North Atlantic.

Ryan Oeste, MS Geology May 2023- “Marine Isotope Stage 4 Changes in Hydroclimate of Southern Portugal.

Alaina Chormann, MS Geology May 2022- “Insights into the hydroclimate during the Medieval Climate Anomaly, Little Ice Age, and Industrial Era from annually resolved southern Portuguese speleothem records.”

Hannah Carroll, PhD Environmental Science and PhD Ecology and Evolutionary Biology, 2020 – “Late Quaternary paleoecology of the North American midcontinent.”

Diana Thatcher, PhD Geology 2020- “Using Portuguese stalagmites to constrain Holocene arid and humid intervals and drivers of regional hydroclimate.”

Nina Whitney, PhD Geology and PhD Environmental Science, 2020- “Using modern and paleoceanographic isotopic systems to reconstruct Late Holocene temporal oceanographic variability in the rapidly warming Gulf of Maine.” For more information on Dr. Whitney’s research, please visit

Juan Carlos Romero Gelvez: MS Geology, July 2019 – “A 50 kyr rainfall record derived from Colombian stalagmites: insights on intertropical convergence zone dynamics and the role of ocean circulation.”

Jared Ballew: MS Geology 2018- “Refinement and utilization of the marine climate proxy Arctica islandica: An ideal replication strategy for stable isotope studies and an investigation into the shell growth and hydrographic variability of Georges Bank (Northwestern Atlantic).”

Madelyn Mette: PhD Geology and PhD Environmental Science 2017- Arctica islandica shell growth and geochemical records from northern Norway as North Atlantic marine climate proxies for the last millennium.”

Diana Thatcher: MS Geology and MS Environmental Science 2015 – “Developing a decadal-scale stalagmite record of hydroclimate and atmospheric variability for western Iberia (Portugal) during the Late Holocene.”

Erin Lower: MS Geology 2012 – “A high-resolution geochemical proxy record of radiocarbon and oxygen isotopes in the Gulf of Maine using Arctica islandica shell carbonate.”

Shelly Griffin: MS Geology 2012 – “Applying dendrochronology visual crossdating techniques to the marine bivalve Arctica islandica and assessing the utility of master growth chronologies as proxies for temperature and secondary productivity in the Gulf of Maine.”

Erin Beirne: MS Geology 2011 – “Pursuing a proxy for carbon cycling in the temperate North Atlantic: an investigation of the utility of Arctica islandica shell carbonate to millennial scale dissolved inorganic carbon reconstructions.”

Previous Undergraduate Researchers and Laboratory Assistants

Elise Thrap

Ashton White

Karine (Kari) Holmes

Lindsey Jarosinski

Taylor Rouse

Kayla Wernsing

Grace Murphy

Ian Searles

Gabrielle Heidrich

Owen Tazelaar

Alexis Gruber

Aubrey Foulk

Katie Luzier

Jesse Matt

Jared Ballew

Claire Gruver-Pandich

Shaina Ives

Hayley Nelson

Dana Korneisel

Andrew Lane

Megan Hosford

Ron VanDenBroeke

Jessica Feenstra