Veer off I-5 north of LA for a short hike on the Oak Flat Trail.

The Oak Flat Trail, the only developed hiking trail along the Interstate 5 corridor through Angeles National Forest, offers ever-widening vistas of the fault-tortured canyon country north of Los Angeles. Drop by here sometime for an exercise break from driving while heading toward Northern California, or back home to San Diego.

The trail originates near Oak Flat Campground, tucked away in a large oak grove. To get there, exit I-5 at Templin Highway, about 45 miles northwest of central Los Angeles. Pick up the frontage road on the west side of I-5 (old Highway 99, formerly the main highway) and drive an additional 3 miles northwest to the campground entrance. Turn left and continue 0.3 mile to a parking area just short of the Verdugo Oaks Boy Scout camp. You'll need to obtain a National Forest Adventure Pass ($5) for your parked car.

The signed Oak Flat Trail begins on the left side of the big, grassy area just inside Camp Verdugo Oaks. Nicely constructed switchbacks take you under a shady canopy of stately valley oaks and live oaks. Soon, however, you emerge into the sun on scrub-covered slopes. Mileposts and trailside benches are thoughtfully provided along the zigzagging ascent.

At 1.4 miles you reach a dirt road called the Whitaker Spur Road. From there you can look west into the gorge of Piru Creek -- and if it's clear enough, farther west into the remote Los Padres National Forest country where a half dozen summits over 5000 feet raise their shaggy heads. In the foreground is a dramatic rock outcrop with a window in it.

At this point you're standing just east of the San Gabriel Fault, whose trace is not obvious here. The fault continues southeast and east about 70 miles into the interior of the San Gabriel Mountains, where it parallels the West and East forks of the San Gabriel River.

You'll return down the same trail. In the meantime, you may want to try following the Whitaker Spur Road 0.7 mile west to a 4004-foot summit offering a nice view of Pyramid Lake to the north.