See What Thrust Faults Can Do!

The Mt. Diablo thrust fault is the most active thrust fault in the Bay Area. It is still pushing the 3,849-foot Mt. Diablo upwards.

One of the best ways to appreciate the power of this fault is to take the South Gate Road to the peak’s summit and walk the 0.7-mile long reasonably flat loop Mary Bowerman trail. Here you can see the rocks that used to be at the bottom of the mountain at the mountain’s summit as the fault has slowly buckled up the ground. Erosion has exposed these ancient rocks that are up to 190 million years old! The interpretive signs and trail brochure are excellent.

Directions

Mt. Diablo State Park is located east of Hwy. 680 east of Danville and Walnut Creek. Take the El Cerro Road exit in Danville. Head east, and continue straight onto Diablo Road in about 2 miles. After about 2 more miles, turn left onto signed South Gate Road. The narrowest section of this road is actually this section through a rural residential area, so drive slowly. Continue about 5.3 miles to a stop sign and turn right onto Summit Rd. Continue about 5 miles to the summit. Just before the road splits into two one-way segments, park in the small dirt on the right (or park in the larger lot downhill a few yards).

For more information, visit the Mt. Diablo State Park website and the Mt. Diablo Interpretive Association website (which has a geology discussion).