Early retreat of the Alaska Peninsula Glacier Complex and the implications for coastal migrations of First Americans

The debate over a coastal migration route for the First Americans revolves around two major points: seafaring technology, and a viable landscape and resource base. Three lake cores from Sanak Island in the western Gulf of Alaska yield the first radiocarbon ages from the continental shelf of the Northeast Pacific and record deglaciation nearly 17 ka BP (thousands of calendar years ago), much earlier than previous estimates based on extrapolated data from other sites outside the coastal corridor in the Gulf of Alaska. Pollen data suggest an arid, terrestrial ecosystem by 16.3 ka BP. Therefore glaciers would not have hindered the movement of humans along the southern edge of the Bering Land Bridge for two millennia before the first well-recognized “New World” archaeological sites were inhabited.