164-12 Tracking Environmental Shifts in the Great Plains with Stable Isotopes in Sedimentary Archives

Session: Advances and Applications of Geochemistry in Archaeology

Presenting Author:

Authors:

Abstract:

The Lime Creek site, an archeological locality on Medicine Creek in southwestern Nebraska, provides insight into the seasonal migration habits and resource use of early Plains Native Americans during the Pleistocene-Holocene transition, a period defined by substantial shifts in climate and resources. Previous archeological and paleoenvironmental research around this site has provided essential context for our understanding of early North American human lifestyles, as it documents patterns of human migration and residence in response to shifts in climate and available resources. For this project, we are analyzing a sediment core to contribute new data to this existing synthesis. Using sedimentology and stable isotope records from the carbonate and organic matter in the sediment, we will look for environmental shifts and align them with documented archeological changes – improving our understanding of human responses to climate change. This project will augment existing work with new techniques and extend the paleoenvironmental record into more recent periods in this region’s history.  

Our project has three different components: (1) documenting sedimentological changes preserved in the core (2) performing stable isotope analyses and (3) radiocarbon dating. We have described sedimentary characteristics of the core such as composition, sedimentary structures, color, and features such as roots and carbonate nodules; we will present these observations as a standard stratigraphic column. We will present the results of grain size analyses from core samples using a Mastersizer instrument, and pair these measurements with our already recorded analyses of the sediment. To obtain a representative stable isotope record from the core, we have also collected 30 samples consistently spaced along the core for stable isotope analyses. We will present δ13C and δ15N records from sedimentary organics, to analyze shifts in organic resources and the potential effects on human residence habits seen at the Lime Creek site; we will also present δ18O and δ13C values of carbonates in the core to examine the role of climate change on the human migration patterns seen throughout the Plains region. Radiocarbon dates will place the rest of the analyses into the known historical context of the region and compare our findings with previously established research. This project will ultimately provide more quantitative historical context to archaeologically determined responses to a changing climate over time. 

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

doi: 10.1130/abs/2025AM-5440

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