Reconstructing Nebraska’s Late Quaternary Paleoenvironment, Landscape Change, and Human–Environment Dynamics Using Diatoms and Optically Stimulated Luminescence Dating

Authors

• Gosia Mahoney, University of Nebraska-LincolnFollow

First Advisor

Sheri Fritz

Second Advisor

Paul Hanson

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Geosciences

Date of this Version

4-24-2026

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree Doctor of Philosophy

Major: Geosciences

Under the supervision of Professor Sheri Fritz

Lincoln, Nebraska, May 2026

Comments

Copyright 2026, Gosia Mahoney. Used by permission

Abstract

This dissertation examines Holocene environmental change and human–environment interactions in the Nebraska Sand Hills by integrating geomorphic, paleoenvironmental, and geochronological data. It presents three complementary studies that together explore how climatic variability, local landscape processes, and human activity influenced environmental systems.

The first study reconstructs the early Holocene evolution of a dune-dammed valley in the central Sand Hills. Stratigraphic, sedimentological, and diatom evidence indicate that eolian activity resulted in a blocked fluvial system, leading to elevated groundwater levels and the formation of a wetland that later developed into a lake. Notably, this transformation occurred under relatively dry conditions, demonstrating that major hydrologic changes can result from internal geomorphic processes rather than increased effective moisture. Subsequent drainage of the system reflects a shift in hydrologic balance, likely tied to greater moisture availability during the middle Holocene.

The second study focuses on the Lynch archaeological site in northeastern Nebraska. It provides new chronological constraints on Holocene-age sand reactivation at the eastern margin of the Great Plains and sheds light on its temporal relationship to human occupation. Results confirm geographic variability in dune responses to climatic change and emphasize the importance of local environmental conditions and the influence of human land use. While two episodes of dune reactivation coincide with regional droughts, the timing of the youngest sand reactivation after site abandonment suggests that anthropogenic disturbance played a role in destabilizing the surface and triggering sand movement.

The third study applies optically stimulated luminescence (OSL) dating to ceramic materials from the Lynch site, many drawn from museum collections. The resulting ages align with sediment and radiocarbon chronologies, supporting the reliability of OSL dating for ceramics and providing independent and complementary chronological data on the timing of site occupation. The study highlights the broader potential of curated collections as valuable sources of new geochronological data, particularly for sites where additional excavation is not possible or where datable materials are limited.

Together, these studies demonstrate that Holocene environmental change reflects the combined influence of climate, geomorphic processes, and human activity, contributing to broader understanding of landscape dynamics, resilience, and human adaptation.

Recommended Citation

Mahoney, Gosia, "Reconstructing Nebraska’s Late Quaternary Paleoenvironment, Landscape Change, and Human–Environment Dynamics Using Diatoms and Optically Stimulated Luminescence Dating" (2026). Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–. 458.
https://digitalcommons.unl.edu/dissunl/458