Wednesday, February 16, 2005

Incredibly ancient but still changing:

by Bill Kowinski

The earth is alive. For most places, that might be a cuddly kind of metaphor but on the North Coast, it describes the ground beneath our feet. The land itself is changing more actively than in most places: rising, falling, moving. The North Coast is still shaping itself.

About a month before the Asian earthquake and tsunami put geology on the world news map, I thought I'd start my exploration of the physical North Coast from the ground up, so I visited Susan Cashman, chair of the Humboldt State University Geology department.

Geology is down in the basement of Founder's Hall, and when I mentioned that this seemed fitting since it is the study of what supports us from underneath, Sue told me there was a more prosaic reason. Most geology departments have historically been on the ground floor, she said, probably because of all the heavy rocks they use for study and exhibit. Too heavy to carry up a lot of stairs, and maybe too much of a strain on the floors.

Like me, Sue Cashman is from the eastern half of the continent where the landscape is generally a more settled thing. It changes a little due to erosion, but the last major cause of larger alterations were Ice Age glaciers, some 60 thousand to perhaps 10 thousand years ago in places.

"I grew up in New England and started being a geologist as an undergrad there, so I know those old mountains some," Sue said. "The setting looks similar to this, but that area ceased to be an active plate boundary hundreds of millions of years ago, and it's now incorporated in the middle of the North American plate, which extends from right here in Humboldt County all the way to the center of the Atlantic Ocean."

So today the northeast is "compressing or deforming internally now, but it's being affected more by surface processes that are sculpting it, like river erosion, whereas here in Humboldt county, we certainly have the erosion, but the landscape is still actively forming because we're at a boundary between plates that's causing things to move up and down."

"And there's the action of the ocean," I suggested.

"There's the action of the ocean, and the rainfall destabilizing landscapes, so we have a lot of landslides and rapid erosion ---it's a great place to be a geologist because all kinds of things are happening."

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