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Initial Paleoenvironmental Evidence from the Outer Yukon-Kuskokwim Delta, Alaska

Southwestern Alaska is a critically understudied region of Beringia, highlighted by the lack of paleoenvironmental reconstructions of the Yukon-Kuskokwim Delta (YK Delta). This sub-arctic region is a joint deltaic coastal lowland environment, home to 50 Yup’ik and Cup’ik communities. Anthropogenic climate change dramatically impacts the landscape. Increases in the intensity and occurrence of coastal flooding, the thaw of permafrost and tundra wildfire events have directly affected community resilience and their subsistence way of life. The YK Delta also contributes to the global atmospheric carbon budget as the region’s discontinuous permafrost thaws releasing stored carbon. These issues necessitate the filling of the regional paleoenvironmental knowledge to properly inform native populations and predict future changes to the landscape. Working with two communities on the outer YK Delta, namely, Kongiganak and Mekoryuk, this thesis presents initial paleoenvironmental studies which contribute to our understanding of the impacts of climate change on this region. The first effort documents the development of a loess plateau on the YK Delta during the Last Glacial Period (115,000 – 11,700 years ago), specifically during Marine Isotope Stage III (60,000 – 25,000 years ago), described in Chapter 2. This topic was developed from exposures at Kongiganak and Mekoryuk, and helps to refine the relative sea level history and aeolian processes of the YK Delta. Other efforts on Nunivak Island consist of preliminary results from the first late Holocene lacustrine reconstruction and the first attempt to provide context to coastal dune geomorphology, highlighted in Chapter 3. These efforts help to establish regional paleoenvironmental conditions in the late Holocene, methodology for future sampling, and provide important estimates of long-term coastal erosion.
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