Sibley Volcanic Preserve & Caldecott Tunnel roadcuts ~ 6 miles 1,500 ft climbing

Robert Sibley Volcanic Regional Preserve features a complex volcanic center that was the source, 10 million years ago, of most of the lavas that underlie the ridges from Inspiration Point in Tilden Regional Park to Moraga. Round Top, one of the highest peaks in the Berkeley Hills, consists of lavas, breccias (unsorted mixtures of fine and coarse volcanic debris) and tuffs (lithified volcanic ash – ash that has become stone) that once filled a volcano. (source: Self-Guided Tour handout)

Distance (5-6 miles)

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Elevation gain (each mountain image~ 500 feet)

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Here's a link to our last version of this hike (with photos). (https://www.meetup.com/SF-Bay-Area-Geology-Hiking/events/55975292/)

Terrain: About 1/2 single track trails, 1/4 paved fire trail (the final downhill), 1/4 dirt fire trail. Lots of mud if it's been raining, and perhaps some small stream fording.

We'll meet at the east side of the Caldecott Tunnel (at the roadcuts on the south side of the highway, right near the Fish Ranch Road exit after you come through the tunnel) to examine the beautifully exposed sedimentary rocks there. (Here's a Google map showing our meeting place and the hike: http://g.co/maps/nyk6d .) Unfortunately, due to construction most of the rocks are fenced off, but we'll take a quick look at the stunning layering.

Next we'll drive to better parking at the entrance to the park off Old Tunnel Road (only about 0.5 mile) where we'll start the hike.

We'll hike up the Bay Area Ridge Trail/Skyline Trail to the Grizzly Peak Blvd entrance to Sibley (getting most of our hill climbing out of the way)

The Volcanic hike is describes as "2.2 hours," then we'll walk back down the 1.75 miles to the cars. Plan on about 4-5 hours for the entire hike. Great background on the Volcanic Preserve can be found here: http://www.kqed.org/quest/exploration/sibley-volcanic-regional-preserve-exploration (including an 11 page downloadable PDF guidebook with photos and map markers).

We'll hike rain or shine, so bring your galoshes and other rain gear if it's raining!

If you want to take BART, say so in your RSVP and we'll coordinate pick up from Orinda BART (it's only two exits down the freeway to the Orinda BART station).

We usually get about 20-30 hikers, even when 50-60 are signed up, so I suspect we'll get about the same. But please, remember to change your RSVP if you change your plans.

Bring lunch to snack on. There is water and bathrooms at the top of the hike, but no food for sale.

Sorry, no dogs.

$1 is collected at the start of the hike. This helps defray the Meetup registration and other small costs.

Those who are BARTing or can pick up people from BART: We'll on meet at Orinda BART at 9:30 AM for carpooling the two exits up Highway 24 to the start of the hike. There is only one exit from Orinda BART, so it will be easy to find people. Meet out front in the passenger loading zone (careful, don't park in the bus spaces).