Deglaciation of the Uinta Mountain Range: The role of paleoglaciers for human settlements in northeastern Utah

Reconstructing the pattern of glacier advance and retreat in the Uinta Mountain Range of northeastern Utah following the Last Glacial Maximum (ca. ∼21 ka) is important for understanding the paleohydrology and migration patterns of early humans in the area. Moraine boulder ages suggest glaciers reached their maximum extent by 17.4 ± 0.5 ka, but little is known about how long the glaciers persisted or whether their contribution to stream discharge was significant over time. Of particular interest is whether these glacier systems were large enough over the past few thousand years to sustain settlements during drought periods. Paleoclimate and model data indicate a period of extensive and sustained aridity in southwestern North America between 1.4-0.7 ka, which coincides with the timing of an influx of Fremont settlements in the Uinta Mountain Range (ca. 1.8-0.7 ka). Here, we present data from two drainage basins from the southern Uinta Mountain Range whose glacial melt may have supplied fresh water to streams adjacent to known archaeological sites identified as Fremont settlements. Our preliminary modeling results suggest that climate conditions were suitable for glaciers to persist at least until 1 ka. We will further constrain our modeling results using lake cores from high elevation cirque lakes within the drainages. Bottom ages from these cores will hopefully provide theoretical limits on the timing of deglaciation, and through a combination of glacier and climate modeling we will reconstruct the glacial history of these basins from maximum extent to complete deglaciation. This project is ongoing, and future work will be directed towards further constraining the size of these paleo-glaciers over time from detailed mapping and dating of glacial features. This work will also focus more on the human aspect of the importance of paleoglaciers as freshwater resources during periods of prolonged drought in the Uinta Mountain Range. This research highlights the role of alpine glaciers as freshwater resources in arid, drought-prone regions, and can be applied to understanding migration and settlement patterns of both prehistoric and modern humans.