Sibley Volcanic Regional Preserve

This year we're visiting several parks in the East Bay watershed that are an integral part of our emergency water supply. These parks and preserves capture, filter, and store water, but they also provide recreational opportunities right in our own backyard! This time we are visiting Sibley Volcanic Regional Preserve, which is the site of ancient volcanic activity from 9 - 10 million years ago.

Sibley staging area off Skyline Boulevard

Self-serve Visitor Center

The Sibley visitor center provides exhibits that describe the geology of "Round Top" (elevation 1763 feet), and a self-guided tour brochure that also describes the geological features. Round Top Road goes from the visitor center to the top of Round Top. Volcanic Trail contains most of the stops on the self-guided volcanic tour.

Sibley's geology

Sibley's geological history

The 928 square acre park was opened in 1936 as Round Top, with the formation of the Park District. In 1972 the park was renamed to Sibley Volcanic to honor Robert W. Sibley, a Park District founder and director.

Overlook Trail

View from the water tower - Mount Tamalpais (upper left corner)

View of Wildcat Fault

Sibley Volcanic Regional Preserve provides great opportunities to study the core of an ancient volcano. Follow the self-guided tour of Round Top to learn more about the site. The picnic site looks a little stark, but I was surprised to find a cooling breeze on the day I visited.

Geo Marker 1: Basalt dike

Geo Marker 3: Orinda Formation gravels

Geo Marker 7: Basalt flow

Picnic Area in a quarry pit

Geo Marker 9: hard and soft lava flow

View to Orinda and Mount Diablo

Round Top Loop Trail circles the peak, and provides stunning views of the East Bay and surrounding hills, from Mount Tamalpais all the way to Mount Diablo. In addition to the view, interesting geology, and excellent birding opportunities, check out the several labyrinths and bring your dog.

Coyote bush - green in mid summer	Teasal
Yarrow	Aster

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The trail is completely exposed, so carry plenty of water, and wear a hat and sun screen, especially in summer and fall. In winter, take the road down to the quarry, and look for the California newts in the ponds near the old labyrinth.

Address:  Sibley Staging Area – 6701 Skyline Boulevard; Oakland, CA 94611  Web Site: http://www.ebparks.org/parks/sibley  Map: http://www.ebparks.org/Assets/_Nav_Categories/Parks/Maps/Redwood+map.pdf Wild flowers (sorted by color): http://www.ebparks.org/Assets/files/EBRPD_files/photoguides/wild-flowers/EBRPD_Sibley_Volcanic_Wildflowers.pdf For other parks and preserves in the East Bay watershed, see:  http://edenbythebay.blogspot.com/2017/02/parks-of-east-bay-watershed.html

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