Irreducible geological complexity (not!)

One of the conundrums of darwinian evolution is explaining how complex organs could evolve by means of gradual changes. Specifically, organs that perform a function which seemingly could not be performed at all by simpler, earlier versions of the same organ down the evolutionary tree. Of what benefit can half an eye be, or half a wing? This apparent impossibility is termed irreducible complexity.

In Climbing Mount Improbable, Richard Dawkins gives series of compelling explanations of how these kinds of complex organs might evolve. For example, an intermediate version of the organ may have served a different function than the current one, and performed it well. Only later does evolution "discover", in her haphazard tinkering way, that the organ may be useful for another task.

Biology is not the only field with "How the hell did we arrive at this?" types of questions. Geology has them, too. For example, how can a river ever come to flow through mountains ranges (like the Yangtze and many others do) instead of going around them? Think about it. To erode its way through the range, the river must flow over it in the fist place! But how can it flow over it if the range is not yet eroded?

Turns out that there are explanations for this. One is Antecedence: the river was there before the mountain range started to rise, so it had time to erode it. Another is Superimposition. In this latter scenario, the mountains were there first. At one point, an adjacent lowland get filled by sediments for whatever reason, so that the mountains are now part of a plain. If a river comes to flow through that plain, it can erode those sediments and reveal once again the mountains underneath, all the while carving a path trough them.

We are used to thinking of geographic features as something static, and even if not static, as something that changes in dull and uninteresting ways. But landscape evolution can be as fascinating as its biological counterpart. There's a moment in Alan Moore's Watchmen in which Doctor Manhattan takes his girlfriend to Mars and gives her an speech to that effect, touching on the beauty of inanimate landscapes.