Port Eliza cave: North American West Coast interstadial environment and implications for human migrations

Abstract

The timing of Late Pleistocene glacial advance, retreat, relative sea level and environmental viability between 25 and 12.5 ka ( 14C yrs BP) remain a key issue in the feasibility of a coastal migration route for the first North Americans. This is discussed on the basis of stratigraphic, radiometric and faunal data for Port Eliza cave, a raised sea cave, on the west coast of Vancouver Island, British Columbia. Ice cover is indicated by the occurrence of 2 m of laminated clay, representing deposition in a subglacial lake. From immediately below this clay a diverse vertebrate fauna of marmot, vole, marten, cervid and various species of birds and fish was recovered, yielding ages of 18–16 ka. These dates and others from the region show that ice cover on the outer coast was brief, from ca 15.5–14 ka. The fish species indicate that relative sea level was close to the cave and that salmon runs were likely present. The terrestrial vertebrate fauna is consistent with a cool, open parkland environment with maximum summer temperatures cooler than present; these conditions lasted until at least 16 ka. With a diverse fauna and favorable climate, humans could have survived here on a mixed marine-terrestrial diet, confirming the viability of the coastal migration hypothesis for this portion of the route.