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Outlining Last Ice Age Glaciers in Central-Western Wyoming

Semester: Summer 2023


Presentation description

During the last Ice Age, many of the mountain ranges in the western United States were covered with glacial ice in the form of glaciers and ice caps. These glaciers grew because, (probably put climate cooled first here) as the climate cooled, the elevation above which snow accumulation exceeds ablation, or the Equilibrium Line Altitude (ELA), dropped below the topography as the climate cooled. When the climate warmed at the start of the current interglacial period, these glaciers began to retreat and eventually disappear because the ELA rose above the landscape and annual snow accumulation could no longer overcome the increasing ablation rate. The evidence of these glaciers' presence remains in the depositional and erosional landforms they left behind, the most notable of which are loose deposits of rock called moraines and ""U-shaped"" valleys. This study aims to find these features in the mountains of Wyoming and use them to create outlines of glaciers as they appeared during the last Ice Age. These outlines are given a confidence rating based on how much evidence the glacier left behind, and the highest confidence outlines are used to create estimates for local ELAs using an assumed Accumulation Area Ratio of 60/40. Determining past glacial extent allows for more accurate estimates of paleoclimate during the last ice age based on glacier modeling. These models will provide a better understanding of how glaciers react to warming climates over longer timescales and more diverse ELA conditions than we can infer from the active glaciers of today. We observed evidence for 329 distinct paleoglaciers with a total area of 1387.96 km2, including indications of a previously undocumented ice cap across parts of the Wyoming Range. We also observed a preference for larger glaciers across ranges with more high-elevation areas. This will allow for more accurate predictions of how modern glaciers might evolve in the face of ongoing anthropogenic climate change.

Presenter Name: Marcus Tanner

Presentation Type: Poster
Presentation Format: In Person
Presentation #23
College: Mines & Earth Sciences
School / Department: Geology and Geophysics
Research Mentor: Leif Anderson
Date | Time: Thursday, Aug 3rd | 9:00 AM