Saturday, August 29, 2009

Sometimes Rocks Fall

The forces of nature conspire to make rocks fall, it seems.

First you have the forces that Earth’s mantle exerts as it shoves cold oceanic plates underneath the lighter less dense continental rocks.

Then you have the nuclear forces that heat up the cold descending slabs, making them buoyant and they rise and emplace and inject themselves, renewed as they cool to igneous rocks in the cool continental crust.

Then the forces in Earth’s continental crust cause deformation of the crust, uplifting the granitic rocks that are then exposed to the air by subsequent erosion of the overburden.

Then the forces of gigantic ice sheets form and shape these hulking rocky tors into smooth U-shaped valleys with steep, nearly vertical walls.

And sometimes, yes, vertical walls.

Then the weakest force in the universe, gravity, carries the rocks down, calamitously, into the valley below – taking out a few Mercedes Benzes along the way.

So in Yosemite Valley yesterday, part of the Royal Arches, which overlooks the posh Ahwahnee Hotel fell into the valet parking lot at the hotel.

Unleashing another force of nature known as the auto insurance industry.

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