ON-RAMP : Finding Fault

You’ve certainly heard about it, surely read about it and you’ve probably felt it, but chances are you have never seen the San Andreas fault. This terrifying, destructive geological entity, perpetrator of the 1906 San Francisco quake, co-conspirator in the 1989 Loma Prieta shaker and one of the most active fault systems in the world, stretches 600 miles from the top of California to the Gulf of California.

Most of its length is not very visible; its path can sometimes be traced from a helicopter--follow the jagged little gorge--but can’t be appreciated from the ground.

Except near Palmdale, where Highway 14 passes through a deep slice in the Earth. Even geologists, who can be somewhat jaded about rocks, call the Palmdale cut “spectacular.”

To examine this huge rock ruffle, drive north from downtown on Interstate 5 to Highway 14. Exit at Avenue S. Manmade Lake Palmdale will be on the right. Turn left at the end of the off-ramp, go under the freeway and park on the right side of the road, just past the southbound off-ramp. Follow the trail up the hill, staying to the left of the ragged freeway fence, until you reach the crest. Look east, across the freeway. Stare in awe. Be aware, however, that this is not the real fault, just its handiwork.

A caution: Do not be tempted to climb through the fence; this is a fault zone, and a tiny tremor could catapult you onto the freeway.

On the way back to your car, stop near the bottom of the slope and look out at Lake Palmdale. The fault, the real one that has been pleating the landscape, is literally underfoot. It goes beneath the freeway just south of the cut and under a corner of the lake. Looking closer, you might notice a rupture in the concrete drainage trench, and beyond it, several cracks in the off-ramp.

The Earth moves in mysterious ways.