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164-2 New insights on radiocarbon dating freshwater mussel and snail shells at archaeological sites in the eastern U.S.

Session: Advances and Applications of Geochemistry in Archaeology

Presenting Author:

Jason Rech

Authors:

Rech, Jason A¹, Ratvasky, Emily², Champagne, Lilly Arnold³, Kent, Sydney E.⁴, Shoobs, Nathaniel F.⁵, Goodwin, David H.⁶

(1) Department of Geology, Miami University, Oxford, OH, USA, (2) Miami University, Oxford, OH, USA, (3) Miami University, Oxford, OH, USA, (4) Miami University, Oxford, OH, USA, (5) The Ohio State University, Columbus, OH, USA, (6) Denison University, Earth and Environmental Sciences, Granville, OH, USA,

Abstract:

Freshwater mussel and snail shells are common at many archaeological sites that are adjacent to streams in the eastern U.S. As these shells are composed of aragonite and contain carbon, they can be radiocarbon dated to ascertain the age of a stratigraphic horizon or the age of a shell-bearing artifact not associated with a cultural horizon. Many streams in the eastern U.S., however, have carbonate rocks present in their watershed that cause Freshwater Reservoir Effects. We determined that FREs are significant for rivers in the Lower Midwest with carbonate platform rocks in their watersheds. Four Mile Creek in southwest Ohio has an FRE value of 1,029 ± 345, and the Scioto River in central Ohio has an FRE value of 1,265 ± 110. Stream FRE values are also variable throughout the year due to fluctuations in stream discharge and base flow. Therefore, it is important to sample and homogenize a large shell sample (~100 mg) to obtain an average FRE value during the aquatic mollusk’s growth period. Once FRE values are determined for streams with various amounts of carbonate rocks in their watersheds throughout the eastern U.S., it should be possible to predict FRE values to some degree for watersheds based on readily available stream chemistry data.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10964

New insights on radiocarbon dating freshwater mussel and snail shells at archaeological sites in the eastern U.S.

Description

Session Format: Oral

Presentation Date: 10/21/2025

Presentation Start Time: 08:25 AM

Presentation Room: HBGCC, 214D

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