SIPERG Members

Dr. Alan Wanamaker — Professor and Principle Investigator

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

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.

Alaina Chormann — MS Student

I received my BS in Geology from Union College in New York, where I worked in collaboration with the SIPERG on the Portugal Stalagmite project (Collaborative research: Bridging the gap from northern Iberia to northwest Africa to reconstruct atmospheric dynamics and hydroclimate for the last 2,500 years). My MS project is a continuation of this research studying the hydroclimate of southern Portugal using the stable isotopic signature and elemental chemistry of stalagmites.


Alexandra (Alex) Walton — MS Student

I received my BS in Environmental Science from Iowa State University.  My MS project is sclerochronology-based using Arctica islandica clams from the Gulf of Maine region to document climate and environmental change in recent centuries.


Current Undergraduate Researchers and Laboratory Assistants


Karine (Kari) Holmes

Lindsey Jarosinski

Taylor Rouse



Graduate Students

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

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