Saturday, April 17, 2010

Even More Geology FAIL: the Bimini Wall

If you've ever seen any over-the-top documentary about unsolved mysteries, you've probably heard of the Bimini Wall: they're solid rock found dozens of feet underwater that are cut at right angles.

The Bimini Wall is a truly extraordinary feature. They are really impressive. How could they possibly be of natural origin, right? And not made by...say...ATLANTIS?

Personally, I'd prefer the explanation that the Bimini Wall are ancient ruins from lost Atlantis because the actual naturalistic theory of their formation is astonishingly mundane, and a like most stratigraphic and hydrological theories, is actually a little boring. I can't imagine a single scientist in the world that wouldn't be thrilled at the marrow of the idea of discovering Atlantis. But sadly, this isn't it.

The "Bimini Wall" is an example of a geological feature called "tessellated pavement." They're made of a type of cemented together shell-hash, a sedimentary beachrock like the kind found on many shorelines today. What happened was, as the island's shoreline was eroded, the beachrock found itself in the water and broke due to crustal action. The clean breaks and 90 degree angles are due to orthogonal jointing, which is a property of how rocks break due to crustal action (an orthogonal break is, if you remember from geometry, a pair of right angles placed beside each other). As the water starts to flow in between the breaks, the harsh action of the sand and water causes the broken beach rock to assume a loaf shape.

Not only is this possible, but tessellated pavement is actually seen in many places in the world: 90 meters below the water in Dry Tortugas, the so-called "Phoenician Fortress" in Oklahoma, and most spectacularly, the gorgeous Eaglehawk Neck, Tasmania formations.

Anyway, a close analysis of the Bimini Wall shows the total absence of regular and repeated markings that could be interpreted as toolmarks.

Tuesday, April 6, 2010

Geology FAIL

I always have great things to say about Europe. For one thing, it's absolutely unthinkable in the German secondary school system to have someone graduate without taking at least Calculus. That's the kind of rigor we need in the United States: I do not believe these things are beyond the capacity of most students. If we raise expectations students will rise to meet them.

Whatever pluses the education system may have, tragically, the science journalists don't share in the plenty.

I do very much appreciate the efforts of the press to bring to light some interesting elements of science for interested laypeople, but...c'mon. They're presenting as a totally new development that the Alps are growing, something that Geophysics has known about, and provided an explanation for, since the 1850s. In other, closely related news, Abraham Lincoln is still dead.

In short, the Alps were created by the collision of the African plate into the European plate. Despite the fact the two plates are separated, the Alps are actually growing. Why?

A force called isostatic equilibrium. The crust is actually "floating" in an extremely plastic, dense mantle. When you remove weight from something that's floating, it bobs up fast, as the pressure holding the weight down causes the force of buoyancy to compensate. Isostatic equilibrium is actually one of the elements of geology that is left relatively unchanged by plate tectonics.

My German is really, really terrible, but what's doofy is that they're presenting this as news, as a confirmed theory, when it's something most geophysicists have known for 160 years.