Wednesday, November 15, 2006

Breaking the ice

Three weeks ago I was sitting in a meadow at Sheep Pasture with Professor Mooney's environmental studies class, telling them about Frederick Law Olmstead. In passing I mentioned that the place where we were sitting was covered with a half-mile-thick sheet of ice only 15 thousand years ago -- that is, at about the time their Western Civ textbooks begin.

The students were properly incredulous, at least some of them. After all, what I was asking them to believe was as foreign to their common experience as if I had caused the stones to rise from the ground.

Oh, sure they had all heard of the Ice Ages, but for the most part only as some abstract theory of science. Give me an hour of your time, I joked, and I will convince you it is true.

Well, a few days ago I met with the class again, in the woods along the Nature Trail. I showed them an outwash plain, till, south-facing ledges, glacial scratches and grooves, chatter marks, erratic boulders (and described their sources which I had previously tracked down and visited). If I had had a day and transportation I could have showed them kettle ponds, drumlins, eskers, and moraines.

One story, moving ice, explains it all.

The point of science is to find the simplest story that explains the most. The story should involve nothing except natural processes that we see at work somewhere on the Earth today. All of the features I showed the students in our New England neighborhood are identical to those we might see in glaciated places like Greenland or Antarctica.

Did I convince them? I gave it my best shot. The evidence, after all, is overwhelming, not just for a single Ice Age, but for dozens of glacial advances over hundreds of thousands of years. It is a testament to the stultifying power of blind faith that half of Americans believe the Earth is only half as old as the scratches we saw on the rocks.