First Americans: no ice-free entry

[Warpy]

2. Agricultural expeditions to northern Canada are discovering a lot about these people

and it seems ice, especially patchy ice, was their friend, not their enemy.

Caribou are known to travel to icy areas in summer. It's the only way they can avoid parasitic flies. Archeology is finding some pretty sophisticated throwing darts in ice melt, darts that were used with an atlatl for some pretty ferocious accuracy and firepower. Ice wouldn't have stopped these people, it just provided another hunting ground to exploit.

Clark is also ignoring the obvious, seafaring. Some skin boats, notably those from the Aleutians and Ireland, were remarkably seaworthy. They could have fished their way down the coast, accessing the interior by the more southerly routes, groups staying in coastal areas not covered by glaciers.