Round Top Loop at Sibley Volcanic Preserve

Sibley Volcanic Preserve is part of the East Bay Regional Park district. It neighbors Huckleberry Botanic Preserve in the Oakland hills near the Montclair Village. This 2-mile loop around an ancient volcano is an easy, flat, one-hour hike that features lots of gorgeous wildflowers in the spring.

Detail of the EBRPD map

From the unstaffed Visitor Center at the Sibley Staging Area, I took Skyline Trail, which parallels the road, and I hopped on the northern loop of the Round Top Loop Trail. This part of the hike offers some beautiful views of Sibley Park. Here and along the sunny eastern side of the loop, I saw lots and lots of gorgeous wildflowers.

On the eastern side, there is a platform with a picnic table and a guardrail near the Quarry Trail turnoff, offering views of Mount Diablo. If you look down the steep cliffs here, you will see one of the interesting labyrinths featured in the park. You can get down to it to walk through it if you wish, but I had a bit of a time crunch, so I just admired it from above. As you return to the Round Top Loop Trail, you will go through a mixed forest.

The forest is composed mostly of eucalyptus and Coulter pine. This park is one of the northernmost points of the Coulter Pine's range; they are more commonly found in southern California and Baja Mexico; another notable place where you can find this tree is in Black Diamond Mine Regional Preserve, which is also on my list to visit!  You can see neighboring Huckleberry Preserve from this leg of the loop.

At the junction of the loop with the road and the returning trails, I took the Overlook Trail to get back to the staging area. The forest here was mostly unremarkable, except that you can see that the park district is trying to reintroduce redwoods along this path. It is cool to see that restoration in progress! It will really change the feel of the park if the redwoods take off here.

I would definitely like to return to the park with a little more time. I would enjoy actually taking the self-guided Volcanic Trail to learn more about the volcanic/geological history of this area! Here is what the Park District has to say about that:

Round Top, one of the area's highest peaks, is made up of lava and volcanic debris left over from a 10-million-year-old volcano. During the past 10 million years, massive tectonic forces on the Hayward and Moraga earthquake faults uplifted the Berkeley hills, folding bedrock formations and tilting the Round Top volcano complex on its side.

Softer sedimentary rock from the Orinda Formation eroded away, exposing the Round Top volcano. In addition, quarrying in the north half of the preserve has revealed cross sections of the bedrock geology, providing an unsurpassed outdoor laboratory for studying volcanism in the Central Coast Ranges.

I feel like I have scratched the surface of this park, and that I have a lot more to learn from another visit here.