Saturday, November 27, 2010

Oceans on the 8s

It's time for "Oceans on the 8s!" But unlike the Weather Channel, we don't need to update the report every 10 minutes. Once every 8,000 years ought to cover it.

Let's start with the continental rifts, which split the land by pushing it back and allowing a baby ocean to form and grow. The ocean that will be created by the African rift hasn't been born yet, but it's looking healthy. Before long, it will look something like the Red Sea, a rift ocean which continues to grow nicely. (Incidentally, most rifts never create oceans. For instance, in the U.S. two rifts - one near where the Madrid earthquakes happened in 1811-1812 and the other stretching from Oklahoma to Michigan, failed to split North America.

The Atlantic Ocean also continues to grow as the mid-Atlantic ridge keeps spewing out more seafloor. There are no subduction zones off its shores, so it continues to push North America to the west. However, eventually the Atlantic will begin to shrink, and in the end will disappear. The Indian Ocean is hanging at the same size, its mid-Indian ridge and subduction beneath Indonesia balancing each other.

The Mediterranean is shrinking fast as Africa keeps moving north, and the Pacific Ocean also is getting smaller. The subduction zones all around the ocean are eating seafloor faster than it can be produced. (Between the pull of the Pacific and the push of the Atlantic, North America is moving west at about an inch a year.)

That's it for the 2010 report. Look for us again in 2810. (Because 8,000 years is something like 32,000 generations, you'll probably want to take pains to remind your kids and grandkids to keep passing on the word.)

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