Rocks and Water

Great BBC documentary on Youtube of mountain building and collapse highlighting Tibet

This was a post that originally appeared on my old blog.

I was sent a great BBC video entitled ‘Roof of the World’ that does a nice job of outlining many of the modern concepts of mountain building (orogeny) and related collapse (taphrogeny), with emphasis on the Tibetan/Himalayan system and Greece, keeping the tools of the trade central to the story. There is a lot of gorgeous footage of the dramatic mountain scenery, featuring many of the rock stars of the contemporary academic regime (e.g., P. England, J.-P. Avouac, M. Searle, P. Molnar). Despite being almost 15 years old, many of the ideas presented here are still driving the science. The film isn’t as ‘dated’ as some of the commenters would have one believe. With respect to Tibet and the Himalaya, the only Big Ideas not discussed are the channel flow models of the Himalaya (south-directed, a la Beaumont) and of Tibet (east-directed, a la Clark and Royden), which were published a few years after the movie came out. There is also not much discussion of the effect of India’s underthrusting of Tibet, either; the situation is presented as a vertically-homogeneous collision, which of course is a problematic approximation.

While I think my favorite part is the scenery, I am very impressed by the ease with which the theories are communicated and the fluidity with which the field and analytical techniques are integrated into the narrative. The animations definitely help, but a big part of it is simply that many of the modern, cutting-edge concepts in tectonics aren’t actually that complicated. The treatment of lithosphere as a viscous fluid, the effects of mantle delamination, gravitational collapse, etc., are fairly simple and intuitive concepts.

The genius involved in this kind of work isn’t the mental power and agility necessary to get one’s mind around these ideas, it is the mental power and agility required to look at an enormous pyramid of granite and think of fluid dynamics–actually deriving these concepts from the observation is the hard part. Well, it’s one of the hard parts. Figuring out how to quantify and test these concepts (which are hypotheses, of course) against observational data, and to refine, reject and replace them if necessary, is an often harder part. It’ll be interesting to see what the science looks like in another 15 years–I have some predictions on what will stand, fall, or rise, but these will be tested as well.

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