Author ORCID Identifier

https://orcid.org/0009-0003-4241-2417

Date Available

8-14-2025

Year of Publication

2025

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Arts and Sciences

Department/School/Program

Earth and Environmental Sciences (Geology)

Faculty

Michael McGlue

Faculty

Edward Woolery

Abstract

The Sierra Nevada essentially serve as the headwaters of California, providing crucial freshwater to the state through seasonal snowmelt. This water supply is threatened by climate change in complex ways that are not fully understood. Geological records provide a valuable source of information on how the hydrology, limnology, and ecology of the Sierra Nevada region has responded to climate changes of the past. This dissertation presents new sedimentary and paleoecological research from Mono Lake and Convict Lake (Mono County, California) and aims to shed light on environmental changes in the eastern Sierra Nevada from ~16 ka to present.

At Mono Lake, ostracode microfossils were extracted from laminated sediments and evaluated using paleoecological techniques. The ostracode data showed abundance and assemblage changes that have been linked to high latitude hydroclimatic variability during the Late Pleistocene deglaciation and the post-glacial Holocene. This dataset provides some of the first insights on the sensitivity of Mono Lake’s benthic ecosystem to environmental change. In addition, prominent grey non-volcanic event layers in Mono Lake deposits were examined using geochemical and petrographic techniques. These layers are most abundant at the Pleistocene-Holocene transition and in the Early Holocene until ~10 ka. The presence of these non-volcanic event layers appear to be connected to erosion of the lake margins following a major regression, and potentially storm activity in an evolving post-glacial hydroclimate in Mono Basin.

At Convict Lake, CHIRP seismic reflection, sedimentary, and palynological datasets were examined to assess paleoenvironmental changes in the Convict Creek Basin in the Late Pleistocene and Holocene. Formation of Convict Lake is captured in both seismic and sediment core data, and most likely occurs around 10 ka and is marked by a prominent transition from glacial to lacustrine facies. Lacustrine sediments and pollen data suggest a transition from relatively dry conditions in the Middle Holocene to variable but dominantly cool and wet conditions in the Late Holocene. Sedimentary proxies of hydroclimate and vegetation from Convict Lake are influenced in part by the geomorphology of Convict Creek Canyon, which provides topographic sheltering and persistent snow and ice at high elevation.

Both Mono and Convict lakes show evidence for sensitivity to temperature and precipitation changes in the Holocene. Due to the impacts of volcanism in the region, coring and radiocarbon dating sediments from these lakes remains challenging. However, when combined with other records from the region, these new datasets provide a more complete picture of the impacts of Late Quaternary environmental change in the eastern Sierra Nevada that may help scientists better predict future tipping points.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.339

Funding Information

National Science Foundation (Award #1829093) in 2018

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