Eric W. Portenga

Associate Professor
Geography & Geology
Eastern Michigan University
Ypsilanti, MI

About Me

I am a geomorphologist who uses cosmogenic nuclides and other tools to study the rates and spatial patterns of landscape evolution, their relationship to topographic, climatic, and tectonic forces, and to place landscape response to human land-use practices in a geological context.

Education

Ph.D. 2015

Earth Science
University of Glasgow
& Macquarie University

M.S. 2011

Geology (Geomorphology)
University of Vermont

B.S. 2008

Geological Sciences
University of Michigan

Current Projects

Dating ice retreat and advance along the lobate southern margin of the Laurentide Ice Sheet with terrestrial cosmogenic nuclides

Summary: This project is in the start-up phases and will begin in earnest in Summer 2025. Over the next four years, this project seeks to re-examine the timing of Laurentide Ice Sheet retreat from the southern Great Lakes region. Specifically, we will be determining exposure ages of glacial erratics left behind by the retreating Lake Michigan, Mackinac, Saginaw, and Huron Lobes of the Laurentide Ice Sheet. This project will develop the research capacity of Geoscience faculty at Eastern Michigan University, make courses with Great Lakes glacial content more accessible to EMU undergraduate students, and kick-start the Great Lakes Earth Exchange, an invited speaker series predominantly for graduate students from other universities in the Great Lakes to speak to EMU undergrads to share findings from their research and give career advice on going to graduate school.
Funding: National Science Foundation, Geoscience Directorate, EMBRACE scheme

Image: Quaternary Geology map of Southern Michigan, produced by Farrand and Bell (1982)

Erosion of the Santa Monica Mountains

Summary: This project uses basin-averaged 10Be erosion rates from streams draining the Santa Monica Mountains, California, to elucidate the relationship between erosion and uplift along the Malibu Coast and Santa Monica Faults.
Funding: Purdue University PRIME Lab Seed Data Grant

The Woolsey Fire and 10Be

Summary: This project seeks to understand how sensitive 10Be measured from stream sand is to widespread erosion associated with recent, large-magnitude geomorphic events, and this study uses the 2018 Woolsey Fire as a case study.
Funding: NSF Award No. 1939000, EMU James H. Brickley Endowment for Faculty Development

Laurentide Ice Retreat
from the Sturgis Moraine

Summary: This project uses 10Be and in situ 14C exposure-age dating on glacial erratics positioned on the Sturgis Moraine in south-central Michigan to determine when the Saginaw Lobe of the Laurentide Ice Sheet retreated after the Last Glacial Maximum.
Funding: Advancing Geochronology Science, Spaces, and Systems - Diversity in Geochronology (AGeS-DiG)

Schmidt hammer exposure-age dating
in the Great Lakes region

Summary: This project seeks to establish a Schmidt hammer exposure-age calibration curve for the Great Lakes region, which if successful will allow for cost-effective and rapid exposure-age estimation of erratics and the landforms on which they are found.
Funding: EMU Provost Research Support Award

Dating eskers with 10Be

Summary: This project will use 10Be dating to determine the deposition and/or exposure age of an esker in the Upper Peninsula of Michigan.
Funding: Purdue University PRIME Lab Seed Data Grant

Updating the Global 10Be Erosion Database

Summary: This project seeks to reanalyze a global database of 10Be erosion rates by updating Portenga and Bierman (2011, Understanding Earth's Eroding Surface with 10Be, GSA Today) with hundreds of new bedrock erosion rates and thousands of new basin-averaged erosion rates inferred from measurements of 10Be.
Funding: EMU Summer Research Award

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