Insect Fossils and Late Quaternary Environments of South- Western Alaska

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Late-Quaternary paleoenvironments of southwestern Alaska have received little study, and the relationship of past environmental changes in this region to those in more-interior regions of Beringia is not yet completely understood. Analyses of fossil insect and pollen assemblages from late-Quaternary sediments of the Nushagak, Holitna, and Upper Kuskokwin lowlands have yielded significant new information on this previously neglected region of the Beringian refugium. Conditions somewhat more humid than those at interior sites apparently persisted in southwestern Alaska during the late-Pleistocene, and this region may have provided refugial environments for insects that could not survive at more-continental localities. Fossil assemblages of stenothermic insect taxa also provide a means of constraining past summer temperatures in this portion of Alaska, contributing to our knowledge of climatic conditions in Beringia as a whole. One of the strengths of the research project is the analysis of multiple sites from the southwestern Alaska region, allowing a clearer picture of the regional paleoenvironmental signal and the degree of local variability. These paleoentomological and palynological studies will provide a more complete late-Quaternary paleoenvironmental record for southwestern Alaska, with emphasis on (1) the transition from last-glacial to Holocene climates and (2) the possibility of a Middle Wisconsinan warm interval previously recognized only in interior regions of eastern Beringia. The results of the study will contribute substantially toward the determination of late-Quaternary climatic and environmental gradients across the Beringian subcontinent and toward an understanding of the ecological dynamics of this late-Pleistocene refugium.