QUAKE FAULTS

Los Angeles’ jagged seascapes, mountain ranges and sweeping valleys were shaped by the San Andreas and other faults. Here’s a look at some striking, even bizarre topographical creations of earthquakes. 1. TEJON PASS

One of three major Southern California mountain passes created by the San Andreas Fault, where the Golden State Freeway cuts through the heart of the fault zone. A band of black, pulverized rock is visible in the deep road cut. The fault can also be seen along Gorman Post Road, where a row of ponds mark the main trace of the fault.

2. ANTELOPE VALLEY FREEWAY

The road cut along the Antelope Valley Freeway exposes the spectacular action of the San Andreas Fault, where layers of sedimentary rock have been bent and contorted by compression--most recently by an 1857 earthquake whose magnitude is estimated at more than 8.0. To get the best view, park along Avenue S just west of the freeway and walk up the hill.

3. DEVIL’S PUNCHBOWL

Wedged between the San Andreas and Punchbowl faults, these 1,300 acres of tan and pink sandstone have been compressed, folded, broken, uplifted and eroded into a grand geological display dating back more than 12 million years. The rocks that were once horizontal have been tilted upright by compression between these two major faults. To see this wilderness area and nature preserve, take the Golden State Freeway to the Antelope Valley Freeway and exit at Pearblossom Highway, which joins California 138. Continue east to Pearblossom. Go south on Longview Road (County N6) and follow the county route and signs to Devil’s Punchbowl County Park.

4. LAMONT ODETT OVERLOOK

Vivid evidence of the crushing and folding effects of fault action can be seen at this overlook, named for the former part-owner of the Antelope Valley Press Newspapers. It is at the edge of the San Andreas Fault zone overlooking Lake Palmdale off the Antelope Valley Freeway, about two miles north of the Pearblossom Highway exit. Northbound drivers can stop at the Vista Point turnout south of the Avenue S off-ramp. A plaque points out the fault line.

5. ARCADIA WILDERNESS PRESERVE

In the foothills of the San Gabriel Mountains is a series of east-west trending faults known as the Sierra Madre Fault zone. A fault scarp can be seen on the west side of the preserve, about 200 feet upstream from the bridge. It appears as a sharp juxtaposition between two contrasting rock types. Take the Foothill Freeway to Santa Anita Avenue, drive north toward the mountains about one mile, turn right on Elkins Avenue and left on Highland Oaks Drive. The entrance to the park is about one mile north. The preserve is closed on weekends except by reservation.

6. THE EAGLE ROCK

On the south side of the Eagle Rock Fault zone stands a 50-foot boulder whose configuration gave the community of Eagle Rock its name. Part of the 20,000-foot-deep fault runs along the back of the prominent rock. Take the Ventura Freeway to the Figueroa Street exit. Go south one block to Colorado Boulevard, turn east on Colorado and then north on Patrician Way. Cross over the freeway, park before the street narrows, and walk north about 100 feet. On the left side of the road, at the base of Eagle Rock, look for a change from pebbly sandstone to crushed rock.

7. PACOIMA CANYON

A few yards off Little Tujunga Road is a microcosm of the natural forces that shaped the mountains. The San Gabriel Fault, exposed in the cliff face, lies between two massive rock formations. A few feet away, a small stream steadily erodes the cliff. To get there, take the Foothill Freeway to Little Tujunga Road and drive about 10 miles north. The area is identified by a Forest Service marker.

8. BENEDICT CANYON

Along the San Diego Freeway, south of Getty Center Drive, look west for a change from light sandstone to a dark gray layered shale, showing where the Benedict Canyon Fault crosses the freeway about half a mile north of Sunset Boulevard.

9. TOPANGA CANYON

The Tuna Canyon Fault zone crosses Topanga Canyon. Drive 2.2 miles north of Pacific Coast Highway on Topanga Canyon Boulevard and park just north of the bridge at the entrance to the narrows of the Topanga Canyon. Look for an abrupt change from very light-colored sandstone to layers of a reddish-brown pebbly rock, or conglomerate, which look like they have been sliced.

10. SYLMAR

To find the Mission Wells Fault in the San Fernando Fault zone, take the Rinaldi Street exit of the San Diego Freeway. About three-quarters of a mile north of the exit, look for what is called a “zone of disruption,” where gray shale rocks are dislodged from hillside and, in some cases, crumble when picked up.

11. SIMI VALLEY FREEWAY SUMMIT

In the Chatsworth area, one of many small unnamed faults can be seen in the deep road cuts at the summit of Simi Valley Freeway west of Topanga Canyon Boulevard. Look for offsets in the layered shale and sandstone. This area can be seen from the south side of the freeway, across from Call Box No. 4.

Source: Geologist and tour guide John Alderson of the Wilderness Institute