East Bay Regional Park District,
Contra Costa County
In brief:
This east bay hills loop includes a self-guided tour through ancient volcanic
features, and hosts a Bay Area Ridge Trail segment.
Distance, category, and difficulty:
This 2.6 mile loop hike is easy. Trails have minimal elevation
changes and the preserve is small. Trailhead elevation is around 1400
feet. The featured hike climbs to about 1600 feet, then descends back
to the trailhead -- total elevation change is about 500 feet.
Exposure:
About half shade, half full sun.
Trail traffic:
Moderate, with lots of local foot traffic.
Trail surfaces:
Dirt fire roads and trails, and 2 short segments on pavement.
Hiking time:
1 hour.
Season:
Nice all year, but best in spring.
Getting there:
From CA 24 in Alameda County, exit Claremont (exit 3). Drive about 1.5
miles northeast on Claremont Avenue to a major intersection with Ashby. Continue
straight through the light, then turn right to remain on Claremont Avenue
(Claremont Boulevard veers left). You should see a brown "parks"
sign for Tilden and Sibley Parks, then pass the back on the Claremont
Hotel on the right. Continue on Claremont about 2 miles to the intersection
with Grizzly Peak Boulevard. Turn right and drive about 2.4 miles
to the intersection with Skyline Boulevard. Turn left onto Skyline,
and almost immediately, after 0.1 mile, turn left into the preserve entrance.
GPS Coordinates* for Trailhead:
Latitude
Longitude
(* based on Google
Earth data, shown as degrees, minutes, seconds)
Gas, food, and lodging:
Gas, restaurants, pay phone, and stores near the junction of Claremont
and Ashby, about 3.5 miles to the northwest. No camping.
Trailhead details:
No entrance or parking fees. Parking for about 25 cars in two gravel
lots. Be sure not to block the gate to the right of the visitor center,
as utility vehicles use this paved road regularly. Restrooms and drinking
water at visitor center. Detailed map and self-guided tour pamphlet available
at visitor center. Public transportation info from EBRPD: Take "AC
Transit bus #5 and exit at the stop of Colton Boulevard and Ridgewood
Drive. Walk the short distance from Colton to Skyline Boulevard, turn
left and proceed to the park. It is a mostly level, 0.9 mile walk."
There is no designated handicapped parking.
Rules:
Most trails are hiking and equestrian only. A few trails are multi-use.
Dogs are permitted at Sibley, but are not allowed on adjacent Huckleberry
trails. Park is open from 5 a.m. to 10 p.m., unless otherwise posted.
The Official Story:
EBRPD's
Sibley page.
EBRPD headquarters 510-562-PARK
EBRPD's
Sibley brochure pdf
Map Choices:
• Use AAA's San Francisco Bay Region map to get there.
• Map
from EBRPD (download the pdf) -- includes the self-guided tour.
• Afoot and Afield: San Francisco Bay Area, by David Weintraub
(order
this book from Amazon.com) has a great map and descriptions of a Sibley
hike.
• East Bay Trails, by David Weintraub, has a simple map and
preserve description (order
this book from Amazon.com).
• The Bay Area Ridge Trail, by Jean Rusmore(order
this book from Amazon.com) has a simple map and descriptions of Sibley's
segment of the Ridge Trail.
• East Bay Out, by Malcolm Margolin, has a good history of
the park (order
this book from Amazon.com).
• 
Geology
Trails of Northern California, by Robin C. Johnson and Dot Lofstrom
(order
this book from Amazon.com) has a nice geological description of this
preserve.
Sibley
in a nutshell -- a printable, text-only guide to the featured hike.
View
photos from the featured hike
Sibley
Volcanic Regional Preserve was one of the first three parks established
by the East Bay Regional Park District. Dedicated
in 1936 (!), Sibley is certainly unusual: who would guess that part of
the east bay hills was volcanic? The geologic history of this area
may well catch you by surprise. About 10 million years ago, lava
flowed from here, spreading north to Inspiration Point and southeast to
Moraga. The rock around the volcano eventually eroded, and today
cross sections of the volcano are out in the open for all to see. A
pamphlet available at the (unstaffed) visitor center allows you to take
a self-guided volcanic hiking tour. And along the way, 2 dramatic
labyrinths spark the imagination.
Round Top, the highest point at Sibley,
is distinctive in appearance, height, and location. One of the highest
points in the Berkeley hills, Round Top is perched over and a little south
of the Caldecott Tunnel. It lives up to its name, and once you have
identified its curvaceous profile, you will be able to pick it out of
the east bay hills' profile with ease.
Start your hike at the visitor center, where you can
pick up a pamphlet with the map and self-guided tour, and interpretive
displays show off the different types of rocks, plants, and animals 
at
Sibley. There really is only one loop hike starting at Sibley, but this
trailhead is also an important staging area for hikes to the north (about
3.5 miles to Tilden) and to the south (about 3 miles to the Skyline Gate
of Redwood Regional Park). The "top" of Round Top is private and
off limits, but there are great views from Round Top Loop Trail, particularly
on clear winter days.
For the featured hike, walk down the
steps of the visitor center, turn left, and walk up the paved road. The
right side of the multi-use road drops off to the south, and there are
sweeping views past Huckleberry Preserve
and Redwood Park, all the way to the mountains
of eastern Santa Clara County. Along the edges of the road yellow star
thistle thrives among a plant community of coyote brush, poison oak, Monterey
pine, eucalyptus, California bay, coast live oak, and madrone. You might
notice a few shrubs of toyon, a native plant with elliptical evergreen
leaves and red berries developing in autumn and persisting through winter.
Toyon
is one of 5 vines, shrubs, and trees which produce conspicuous red berries
at Sibley. Look also for madrone, a tree with evergreen leaves, peeling
bark, and marble-sized berries in winter, cotoneaster, a non-native shrub
that puts forth small red berries in winter, hawthorn (notched leaves
and small red berries in late summer and early autumn), and honeysuckle,
a vine that dangles jewel-like berries in autumn. After 0.11 mile, the
road splits at an unsigned junction. Stay to the right on the paved
trail.
Monterey pine, California bay, and coast
live oak crowd the road. At 0.26 mile, you'll reach a signed junction
with Round Top Loop Trail (you might only notice the small path to the
right, but the other part of the trail heads left as well). Turn
right onto narrow Round Top Loop Trail.
The hiking and equestrian trail squeezes
through a forest of Monterey pine. After a few feet, at 0.28 mile, the
Bay Area Ridge Trail/Skyline Trail departs to the right, descending to
Huckleberry Botanic 
Regional
Preserve on the way to Redwood Park. Stay to the left on Round Top
Loop Trail.
Blackberry and a few hawthorn thrive beneath
the pines. The trail, open to hikers and equestrians only, is nearly level.
There is a brief ascent, then a dirt spur trail from the paved road enters
from the left at 0.33 mile. Keep right. Round Top Loop Trail leaves
the pines behind and takes up with some eucalyptus, with an understory
of blackberry, lupine, fennel, poison oak, sagebrush, coyote brush, and
California coffeeberry. The trail, rocky at times, winds levelly through
a forest of living and dead eucalyptus and pine. Charred stumps and fallen
trees serve as evidence of a fire a few years ago. The heat from the fire
opened Monterey pine cones, and there are quite a few young trees making
a fresh start. The eucalyptus trees on
the south side of the trail seem to be dying en masse, giving this section
of the hike a ghostly feel. It's the quietest part of Sibley, and
through the thinning trees to the south you may see deer. Abruptly,
near a cattle gate, the path ascends steeply and emerges into grassland.
At 0.63 mile, a faint path heads right toward the preserve boundary --
walk a few steps to a hilltop with far reaching views. When it's
clear, Mount Diablo is visible to the southeast. When I visited after
a few days of rain in December, the snow-topped peaks of the Sierra were
prominent on the horizon. At 0.78 mile the trail dips down to a T junction. Walk
straight toward a fenced viewpoint and stop #4.
Ten million years ago the pit just downhill
was the interior of Round Top volcano. Quarry mining removed the basalt
lava rocks, leaving the caldera exposed. Some time since then, a
labyrinth appeared. A San Francisco newspaper explored the "phenomenon"
of the labyrinths (you'll visit the second 
one
shortly) in 1999. No one seems to know how or by whom they were constructed.
Small trinkets, foreign coins, and other objects are often piled in the
centers. These convoluted paths are true labyrinths, rather than
mazes, and although I've never seen anyone tending them, the labyrinths
are always perfectly clean and tidy. The whole thing makes me think
of Spinal Tap and the song "Stonehenge," but I guess that's just my weird
mind. Look just to the right of the viewpoint for a cluster of buckwheat,
which produces pink blossoms in autumn. Walk back toward the previous
junction and turn left to visit the labyrinth.
The broad trail descends, with coast live
oak and madrone on the right and patches of willow, sticky monkeyflower,
lupine, and coyote brush on the left. After sweeping down to the quarry
floor, you'll reach the large, crude labyrinth. This area is
often flooded in wet months, when you might see some newts making their
way to standing water. There are plenty of unofficial paths around, and
if you are planning on exploring, take note of the steep drop-offs. When
you're ready, retrace your steps back to the previous junction,
at 1.17 miles. Continue north (straight) on the Volcanic Trail.
Coyote brush dominates the landscape, but
you might also see bushes of lupine. At 1.31 miles, Round Top Loop
Trail heads back to the trailhead, left. Continue straight on Volcanic
Trail.
Along this broad multi-use trail, views
to the northwest open up, past hillsides descending through grassland
to forests of eucalyptus, to Volmer Peak at Tilden Park, and if it's clear,
Mount Tamalpais in Marin County. Traffic noise from Highway 24 is audible.
If you're taking the self-guided tour, look for the numbered posts that
correspond to the pamphlet's descriptions. 
At
1.49 miles, you'll reach a junction near a watering trough. Stay to
the right, then walk a few feet to a second junction. Bear right (ignore
another trail to the right which quickly ends at a gate) and at 1.62 miles
you'll reach the second labyrinth. This one is smaller and vaguely
heart-shaped, and the small bluff overlooking it is a nice, semi-secluded
spot for a picnic (especially if there are no cows grazing nearby). When
you are ready to continue (unless you're taking the self-guided tour,
and then you're on your own), retrace your steps to the junction with
Round Top Loop Trail, at 1.93 miles.
Turn right onto Round Top
Loop Trail, which sweeps around the northern flank of Round Top. The
multi-use trail travels through chaparral, including some big coyote brush
bushes that are lovely when in full fuzz in autumn (the nickname for this
plant is fuzzy wuzzy and this is why). 
You
might also see willow and teasel. Ascending a bit, the trail crosses through
a cattle gate. At 2.33 miles, you'll reach a multi-trail junction. A paved
road returns back to the trailhead, straight, and uphill to a dead-end,
left. The trail to the right splits almost immediately, and both paths
return to the trailhead, but in a much more intimate way (watch out for
poison oak) than the road. Turn right ("to Visitor Center"),
then right again.
The trail, open to hikers and equestrians
only, winds through California bay, blackberry bushes, poison oak, eucalyptus,
and coyote brush. Look for dramatic displays of dangling red honeysuckle
berries in autumn. The trail descends to a moist spot marked with several
large currant bushes. A small interpretive site identifies the hills visible
to the north, and the plants of the park. Two benches make a great
spot to watch birds, large (hawks), small (hummingbirds), and every size
in between. The paved path is lined with madrone, coast live oak, California
bay, and Monterey pine as it returns to the trailhead. At 2.56 miles,
it ends at a gate a few feet from the visitor center and parking lot.
Total distance: 2.56 miles
Last hiked: Tuesday,
December 4, 2001
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