Reconstructing Past Climate and Glacier Changes in the Teton Range, WY from Lake Sediments
Faculty Mentor: Darren Larsen, Geology Department
Funding: Ford Research Mentor's Endowment
Lake sediments preserved on the eastern side of the Teton mountain range contain a continuous history of glacial and climate fluctuations dating back at least 10,000 years. In this study, we focus specifically on the timing of glacial retreat following the last glaciation, the Pinedale glaciation, by observing the transition from glacial to non-glacial sediment in Lake Solitude, a non-glacial lake located at the head of Cascade Canyon. We use physical and geochemical parameters including percent organic material, dry bulk density, and magnetic susceptibility to analyze core samples collected from Lake Solitude.
We find a clear transition between glacial and non-glacial sediment that is characterized by an increase in percent organic material, a decrease in dry bulk density, and a decrease in magnetic susceptibility. The transition to non-glacial sediment reflects the shift from late Pleistocene to early Holocene climate conditions, specifically the increase in summer insolation at the beginning of the Holocene. Additionally, we measure magnetic susceptibility in Bradley Lake and Taggart Lake, two low elevation glacial lakes, and find two tephra layers likely corresponding to the Mt. Mazama (~7.6 ka) and Glacier Peak (~13.6 ka) eruptions (Larsen et. al., 2016). Using Accelerator Mass Spectrometry radiocarbon dating and tephrochronology, we will create an age model to date the timing of glacial retreat that we observe in Lake Solitude. We discuss the Pinedale glacial retreat in the context of past climate change, early Holocene conditions, and contemporary climate change.
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