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Colonizing the Americas via the Northwest Coast

It has long been accepted that the Americas were colonized by a migration

of peoples from Asia, slowly traveling across a land bridge called Beringia (now

the Bering Strait between northeastern Asia and Alaska) during the last Ice Age.

The first water craft theory about this migration was that around 11,000-12,000

years ago there was an ice-free corridor stretching from eastern Beringia to the

areas of North America south of the great northern glaciers. It was this

midcontinental corridor between two massive ice sheets

–

the Laurentide to the

east and the Cordilleran to the west

–

that enabled the southward migration. But

belief in this ice-free corridor began to crumble when paleoecologist Glen

MacDonald demonstrated that some of the most important radiocarbon dates used to

support the existence of an ice-free corridor were incorrect. He persuasively

argued that such an ice-free corridor did not exist until much later, when the

continental ice began its final retreat.

Support is growing for the alternative theory that people using watercraft,

possibly skin boats, moved southward from Beringia along the Gulf of Alaska and

then southward along the Northwest coast of North America possibly as early as

16,000 years ago. This route would have enabled humans to enter southern areas

of the Americas prior to the melting of the continental glaciers. Until the

early 1970s,most archaeologists did not consider the coast a possible migration

route into the Americas because geologists originally believed that during the

last Ice Age the entire Northwest Coast was covered by glacial ice. It had been