FRONTIERS IN BERINGIAN QUATERNARY SCIENCE (Invited Presentation)

Mid-Wisconsin Beringia: People may have crossed the land bridge before the LGM. This possibility highlights the importance of paleoenvironments between ca. 40 and 30 ka BP, which we currently know little about.

New Archaeological Sites: Have we looked in the right places for evidence of mid-Wisconsin habitation? Advances in remote sensing and land-use modeling offer new ways to identify the landforms and depositional environments that the First Americans occupied.

Spatial variability of the Mammoth Steppe: The nature of this extinct biome remains elusive. If it was an azonal biome created intermittently by rapid shifts in climate, then its geographic distribution also shifted rapidly and radically. Can transects of precisely dated paleobotanical sites test this hypothesis?

When did megafauna go extinct? Deciphering what caused an extinction requires precise dating of dwindling populations. The most recent age of a fossil tells us only when that species was last abundant on the landscape, not when it went extinct. Combined ¹⁴C dating and estimates of population size based on aDNA may provide answers.

Megafaunal dispersals: When, exactly, did species like M. primigenius and B. priscus cross into North America and then re-cross to Asia? Why did the Land Bridge act as a one-way valve for many taxa? The dispersal histories of other species may provide insights into when and why people first crossed to North America.

Ice Gates South: Glaciers on the Alaska Peninsula and inner Aleutian Islands blocked entry to the Northwest Coast Route. Current knowledge of the glacial history of the Aleutians is rudimentary, and a wealth of stratigraphy awaits on the Alaska Peninsula.

Sedimentary biomarkers: aDNA and geochemical biomarkers hold promise in describing paleoenvironments; however, they require controls to assure against reworking of molecular fossils, and they need calibration before they can quantify population sizes.

Arctic Ocean glaciation: Ice sheets and ice shelves episodically covered the Arctic Basin. Their presence raises fundamental questions about how the cryosphere interacts with orbital drivers and the atmosphere-ocean system. The paleo-sea level history of northern Beringia records some of these glaciations, and this record is ripe for re-examination using new dating and mapping techniques.