Saturday, November 7, 2009

The Airliner Chronicles: Why are these Volcanoes Here?


A photo from my flight to a GSA meeting in Seattle a few years ago recalls a question that had different answers, depending on when you asked the question, or more like, no answers if you go back far enough in time: Why are these volcanoes here?

The subject popped up in my head as a result of the passing of one on of my professors this last month, Donald B. McIntyre. In reading some of the tributes to his life, I recalled that he had studied under Arthur Holmes, who was one of the pioneers in the acceptance of the hypothesis of Continental Drift, which was later refined into the theory of Plate Tectonics, an idea so radical that it pretty much rewrote an entire science (imagine if the chemists discovered an idea to replace atomic theory). Dr. McIntyre was actually involved in two revolutions of geology: he was also a historian who documented the life of James Hutton in several books.

It just happened that I had picked up and started reading Plate Tectonics: An Insider's History of the Modern Theory of the Earth, edited by Naomi Oreskes. It is composed of 17 essays by the researchers who uncovered the evidence for plate tectonics in which they remember the events in their own lives that led to the new theory. It is fascinating to learn what was in their minds during the 1950's and 1960's as the realization slowly dawned that what they had always accepted about the structure and history of the earth was not necessarily true. What happens when a bunch of young professors and graduate students stumble onto something that was both unknown and unimagined?

Reading these stories made me wonder about something else. What was it like to be a teacher or professor in the 1960's when the revolution of the science was at its height? I came on the scene a bit late to really know, taking my first class in geology in 1975, when plate tectonics was already becoming established in the classroom. If you were in the classroom in the 1960's, how much of the debate filtered into your curriculum? Was it a topic of discussion in classes, or was there even a realization that something big was going on in the science? I'm wondering what it was like for the people who weren't necessarily the pioneers at the forefront of radical research. Anyone want to contribute some thoughts and memories?

The picture is of Mt. St. Helens and Mt. Adams of the Cascade Range. These volcanoes are now known to originate from melting of the crust that occurs as ocean crust (and water) are carried beneath the continent at subduction zones. It was once thought that the extra weight of sediments accumulating on the edge of the continents pushed downwards on the crust to where the heat of the planet melted the deepest rocks.