As you drive north on the Antelope Freeway (CA 14) and round a bend, the San Gabriels abruptly drop off behind and the vast expanse of the Mojave Desert unfurls ahead. On the horizon are the hangars where many of the military’s most secret aircraft are designed and built. These massive buildings rise above a landscape so flat and desolate that only 25 miles farther north the Space Shuttle touches down when the weather is bad in Florida.
The sign ahead says, “Welcome to Palmdale,” but it could just as easily say “Welcome to North America.” That’s because Palmdale is a border town on the North American tectonic plate which begins at the San Andreas Fault, which runs through the southern part of the city.
As most people are aware, the surface of the Earth consists of a dozen or so major “plates” which move in relation to one another. The San Andreas Fault, which runs for about 800 miles within California, forms the boundary between the North American Plate – which extends eastward all the way to Iceland – and the Pacific Plate, which carries most of the Pacific Ocean on its back. Plate boundaries are big deals because they are located where most of the world’s earthquakes and volcanic eruptions occur.
Like ice floes, the plates jostle alongside one another, releasing energy in the form of earthquakes. The Pacific Plate moves to the northwest at about the same speed that your fingernails grow. This may not sound like much, but this rate is just an average. During major quakes, the plates can jump several feet at once. The next major jump along the San Andreas is the “Big One” that everyone in California fears.
The residents of Los Angeles can take some comfort in knowing that their downtown is over 40 miles from the San Andreas. Not so for the 152,622 folks who live in Palmdale. Their proximity to the fault can often be measured in feet. City officials and land developers understandably downplay their city’s connection to the fault line to the point that many residents have no idea where it runs. This was made clear to me recently when a young friend of mine who lives on S Street was shocked to learn that his house was built almost directly on top of the line.
For those curious to find the fault line in Palmdale, ironically the best place to see it is on the Antelope Freeway itself. Just as you enter the city from the south you pass through a road cut that was hewn directly across it. The rock on the sides have been deformed by the tectonic forces beneath into a taffy-pulled swirl. It’s a bit of an oversimplification (as is everything when dealing with tectonics), but the fault line around Palmdale can be found wherever the desert intersects with the mountains. This is no accident as both geological features were created by tectonics. A few miles to the southeast of the Antelope Freeway road cut, near Devil’s Punchbowl, there is actually a sign that points out the fault line – a rare find in property-value-conscious California.
California is not falling into the ocean, as many joke, but instead is shearing itself in two like a piece of string cheese. Eventually, the Pacific Plate will carry itself to the northwest making the portion that today totes the city of Los Angeles a new island off the coast of San Francisco. In the unlikely event that our species is able to survive the 50,000 or so “Big Ones” that it will take to move that huge chunk of real estate 300 miles, the Antelope Freeway could one day conceivably connect up to a new bay bridge linking the twin cities. Then the sign on the highway would no longer read, “Welcome To Palmdale,” but “Welcome To San Francisco.”
For more on the Palmdale road cut, click here: palmdaleroadcut.html
For a YouTube video of us driving through the road cut, click here: http://www.youtube.com/watch?v=oG55wLEgZPM