Thursday, March 8, 2007

Visit the San Andreas Fault!!!

If you've never been to California and always dreamed of visiting or touching the San Andreas Fault (SAF), here's your cyber-opportunity. Thanks to the folks at geology.com and Google Earth, you can now zoom in on the fault and actually "travel" along its linear trace to explore how it affects the landscape. NOTE: If you start at the southern tip and pan up to the northern tip, you'll notice than many drainages and mountains are actually offset (to the right of whichever side of the fault you're looking at). That's because the SAF is a right-lateral strike-slip fault - essentially pulling western California to the northwest and "ripping" western North America apart.

I'm a big fan of the SAF... not because I enjoy the devastating effects of earthquakes or tapping into some deep-rooted psychological fear of "unknown forces" having control over our environment. Nope, it's because the modern landscape of the Western United States owes a lot to this geological feature. The initiation of the SAF, and subsequent extension, lead to the exposure of the Sierra Nevada, Quaternary volcanism, and the development of the Basin and Range Physiograpic Province - characterized by undulating mountains, valleys, mountains, valley, etc.






We have the SAF to thank for these landscapes. It's easy to recognize the negative impact of geologic faults (especially those that misbehave such as the SAF) - it's harder to embrace and appreciate their impact on landscapes dominated by "aesthetic geology." It's harder to embrace the SAF as a benevolent geologic feature because humans face the tension between geologic time and have to embrace 30 million years of geologic unrest versus an instantaneous event that has immediate consequences. I don't think anyone is going to be thankful for the majesty of the Yosemite when they discover their personal belongings are part of the rubble responsible for a new "urban mountain" landscape in downtown San Francisco! However, it is important to keep in the back of our minds that many of the geologic forces labeled "destructive" or responsible for "disasters" are often the same forces responsible for incredibly beautiful and diverse environments.

"It's not the light that we need, but fire; it is not the gentle shower, but thunder. We need the storm, the whirlwind, and the earthquake."
Frederick Douglas

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