Dating an Esker on the Keweenaw Peninsula, Michigan

Eskers are elongated deposits of sorted sediment, often depicted filling subglacial meltwater tunnels. Eskers are notoriously difficult to date. Radiocarbon dating doesn't work well because eskers don't contain much organic material. Optically stimulated luminescence dating doesn't work well because sediment is transported and deposited in these subglacial tunnels without any exposure to sunlight for bleaching. This project seeks to date an esker using cosmogenic 10Be profile dating and comparing that resulting age with exposure ages from two small boulders extracted from the crest of the esker. We are working on the Clear Lake Esker on the northern end of the Keweenaw Peninsula because historical mining rail corridors cut through the crest of this esker, exposing its interior without much extra work. We still exposed 3 m of sediment at its crest for sampling!

Status: Awaiting Data

Participants & Collaborators:

• Prof. Tim Scarlett, Michigan Technological University

• Dr. David Ullman, Burke Center for Ecosystem Research

• Sydney Davis (EMU, Professional Geology, BS, '25)

• The Nature Conservancy

• PRIME Lab @ Purdue University

Funding Sources: 

• Purdue Rare Isotope Measurement Laboratory (PRIME Lab), Seed Data Grant: Can eskers 10Be dated?