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A Journey to a New Land

First people
Multimedia Library

Dr. Michael Wilson

Geology Department, Douglas College

Ice Free Corridor Environment

We’ve been talking about the ice free corridor as if when it opened up it was almost like a superhighway. As if on this steppe tundra and by a steppe I mean grassland, by tundra of course we’ve got an impression of tundra as a sort of herbaceous community. Steppe tundra would have been easy to traverse for these grazing animals. They could have moved quite quickly south through the corridor area. But as always, the story is a lot more complicated than that.

The opening of the corridor was associated with the melting of the ice and so western ice was upslope from the eastern ice a little bit. The prairie slope is, of course, rising to the west. That means that ice that was melting on the west side, the Cordilleran ice, was shedding a lot of water. So the water was flowing across the plains in an easterly direction, flowing eastward and so then it bumped into the Laurentide ice, which was also melting and providing its own water. So then you had a whole series of large glacial lakes that occupied a lot of the ice free corridor. So the ice free corridor wasn’t an easily traversable area, actually. It was peppered with a lot of these big lakes and even worse is the fact that these lakes were ice-dammed. So as the ice retreated more and more to the east, periodically these lakes were able to spill, sometimes catastrophically, spill through little divides southward and eastward on the prairies.

So the ice free corridor area was a scene not only of the formation of very large lakes which would have been barriers possibly to movement of people and animals, but also the scene of repeated outburst floods, where little ice dams would break and the water in these lakes would suddenly shoot out over quite a large area as they drained southward and eastward. In some cases in the northern part of the corridor, the drainage was off to the north so this phenomenon was going on in two directions - from the northern and southern corridor – outburst floods were a constant activity.

That’s kind of a problem too from an archaeological visibility standpoint, because any archaeological sites that were in the area might well have been destroyed by outburst flooding. It’s possible that if you had phenomenon like that going on to really damage some of the record that we see. When you think of this, the ice free corridor doesn’t sound like a simple matter of, “Wait until its open and then we can move southward.”