Plate Tectonics

This week in class we've been talking about plate tectonics. We started by discussing Alfred Wegener and his theory of continental drift. My personal blog is called Continental Drift and I have a "Stop Continental Drift" bumper sticker on my car so I'm a big fan of Wegener. He was a man ahead of his time and didn't live to see the acceptance of his theory. You can read about the reactions to his theory here and here. One of the important advocates of continental drift and plate tectonics was an Australia geologist, Samuel Warren Carey.

After continental drift we discussed seafloor spreading, proposed by Harry Hess. As Callan Bentley writes continental drift + seafloor spreading = plate tectonics. We have only just started discussing plate tectonics in class and talked about the lithosphere and the asthenosphere and divergent plate boundaries today. You can see some animations of plate tectonics, including divergent boundaries, here and here.

There is an interesting blog about using diamonds to date the start of plate tectonics. The isotopic dating of diamonds with eclogitic inclusions, which might be formed from partial melting during the formation of the coeanic crust, shows that plate tectonics may have started around 3 billion years ago.

I also found an interesting series of blogs about subduction denialism written by Brian Romans. You can read these posts here: part 1, part 2, and part3. I never knew there was such a thing as subduction denialism and they tie it in with the expanding earth theory. Part 2 of that series of posts has excellent topographic profiles of various subduction zones/deep ocean trenches.