Tuesday, March 27, 2007

The tale of Alfred Wegener

Earth scientists LOVE the story of Alfred Wegener (pronounced Ve-guh-ner) because it’s the ultimate lesson about brilliance and vindication.

About 4.5 billion years before Alfred was born, the Earth as we know it was still a glint in our Solar System’s eye. Planets like the Earth are formed by the collision and amalgamation of many, many pieces of debris floating around in space. Little bitty dust particles start sticking together, then baseball sized globs of rock and metal start sticking together, then chunks the size of cars, then buses, then tall buildings, and so on and so forth until you’ve got yourself a big-ass planet. What happens then is the metallic stuff that was on those billions of itty-bitty chunks wants to sink down, down, down into the center of your new planet. The densest stuff (like iron and other metals) coagulates in the middle and all the really light stuff like silicate rock floats up to the top.

As you can see from the picture above, we’ve got the metallic Core (inner = solid, outer = liquid iron), then the Mantle which behaves like a plastic in the sense that it does indeed flow, but it flows on the timescale of millions of years. Then up on top we’ve got the part of the Earth that we know and love, the Crust. Our Crust is solid, but it floats around on top of the gooey, convecting stuff below it.

The crust itself is broken up into pieces that we call plates (see above). There are 52 plates in all (1). They range in size from the petite Juan de Fuca plate off the coast of Washington State, to big-mother plates like the Pacific plate which encompasses most of the Pacific Ocean. These plates have been on the move since their very existence – crashing into one another, subducting beneath one another, rifting apart, coming back together, ditching each other for a younger and sexier plate, getting mad and storming off in a huff, cheating on one another with their best friends plate, and…well you get the point.

300 million years ago all the continents were in one gigantic uber-continent: PANGEA (2). But by 180 million years ago the party was over and all the continents started to move into their current positions.

Alfred Wegener took notice of something that seems obvious to most of us now: If you move everything back together, it looked like South America and Africa were totally getting’ it on!

Shame on you, Brazil, taking advantage of the Ivory Coast like that!
Alfred Wegener backed up his new theory of “Plate Tectonics” by pointing out the existence of the same fossils in South America and Southern Africa. He also supported his theory of continental drift by presenting evidence of glaciation found in parts of Africa that are now quite warm. He concluded that Africa must have been closer to the South Pole at some point.

The problem with Alfred’s work was that he didn’t have a mechanism that would explain why the continents would move around in the first place. He proposed a theory suggesting that the continents flung themselves apart via centrifugal force. His claim was that that the inertia of the Earth spinning around was enough to break everything apart and spread it out all over the world like smelly undies in the spin cycle.

As you can imagine, there was plenty of harrumphing and monocle clasping when he presented his ideas in 1912. Nobody bought it. He was scorned and several organizations went out of their way to discredit his work in a very grandiose way. He died at the age of 50, never to see his theory come to fruition.

After WW2, new fangled technology allowed scientists to get a glimpse at what was actually going on under all that fucking water in the oceans. What they saw gave Alfred’s theory of Plate Tectonics the backbone it needed to be widely accepted: sea floor spreading. A paradigm shift ensued and now EVERYBODY believes in plate tectonics, except creationists who are fools. It’s taught in high school, it’s in every Earth Science textbook, it’s on Wikipedia, it’s everywhere. So lets all give props to Alfred Wegener for being ballsy enough to lay it all on the line.

He was awesome.

(1) Bird, P. (2003) An updated digital model of plate boundaries, Geochemistry Geophysics Geosystems, 4(3), 1027
(2) Anderson, D.L. (1990) Planet Earth, pp 65-76 in Beatty, J.K. and A. Chaikin, eds. The New Solar System, 3rd ed., Cambridge Press, Cambridge, 326 pp.

1 comment:

Tara Armov said...

Are you sure you should be listening to a guy who looks like Moe from the Three Stooges?