Black
Diamond Mines Regional Preserve,
East Bay Regional Park District,
Contra Costa County
In brief:
3.5 mile loop through grassland and chaparral, at a preserve which was a former
coal mine.
Getting there:
• From CA 4 in Contra Costa County exit Somersville Road (exit 26a eastbound/26
westbound). Drive south on Somersville to the park entrance.
• If you're driving from San Francisco, or the south bay, these directions
may make your trip quicker (or at least more pleasant): from the CA 24/Interstate
680 interchange in Contra Costa County, exit Ygnacio Valley Road (exit 46b). Drive
east on Ygnacio Valley Road about 8 miles, then the road changes into Kirker Pass.
Continue about 5 miles on Kirker Pass to the junction with Buchanan. Turn right
and drive about 3 miles to Somersville Road. Turn right and drive to the park
entrance.
Trailhead details:
Once inside the park, you can stop at the park office for a map or help with planning
a hike. Then get back into your car and drive to the trailhead at the end of the
road. Entrance fee of $5 charged when entrance kiosk is staffed. $2 dog fee. Drinking
water, maps, and pit toilets at trailhead. Large parking lot. Emergency phone
at park office. There is a designated handicapped parking spot, but trails aren't
wheelchair accessible. There is no direct public transportation to the park, but
you can walk (or cycle) to the trailhead from the Tri Delta Transit route 390
bus stop: visit the Tri
Delta Transit website for details.
Gas, food, and lodging:
Gas, stores, and restaurants back on Buchanan. Camping info from EBRPD: "There
are two camping areas in Black Diamond Mines Regional Preserve. Reservations are
required for both--call (510) 562-2267. Neither camping area has water, so water
must be transported in. Star Mine Group Camp Area, available during spring, summer
and fall, is for organized, educational groups only. It can accommodate up to
40 people. It is located in a grassland/oak woodland community at the eastern
edge of the Preserve. Overnight camping is limited to two nights. Parking (maximum
eight cars), picnic tables and a pit toilet are available at the site. Campers
must bring in their own water and haul out their own garbage. Stewartville Backpack
Camp is for the general public. The fee is $5 per night per person. Camping is
limited to two nights during the spring, summer and fall. There is room for 20
campers. Picnic tables and a pit toilet are available, as well as water for horses
(not for human consumption). The camp is located 3.2 miles from the Preserve headquarters,
near the Stewartville and Upper Oil Canyon trails."
Distance, category, and difficulty:
This 3.5 mile loop hike is on the moderate side of easy. Trailhead
elevation is about 740 feet. The featured hike climbs to about 1250 feet, then
descends back to the trailhead. Total elevation change is about 700 feet.
Rules:
Most trails are open to hikers, equestrians, and cyclists, but a few trails are
designated hiking-only. Dogs are permitted. Park is open from 8 a.m. to dusk.
The Official Story:
EBRPD's Black
Diamond Mines page.
EBRPD's
Black Diamond Mine brochure (pdf)
Park headquarters 925-757-2620
Map/Book Choices:
• Use AAA's San Francisco Bay Region map to get there.
• Map
from EBRPD
• 
A slight variation
of this hike is described and mapped in 60 Hikes within 60 Miles: San Francisco,
by Jane Huber (yup, that's me, the creator of this website). Order
this book from Amazon.com.
• Afoot and Afield: San Francisco Bay Area, by David Weintraub (order
this book from Amazon.com) has a great map and descriptions of a Black Diamond
Mines hike.
• David Weintraub's East Bay Trails has a good map and descriptions
of 3 Black Diamond Mines hikes (order
this book from Amazon.com).
• 101 Great Hikes of the San Francisco Bay Area, by Ann
Marie Brown (order
this book from Amazon.com) has a simple map and descriptions of 2 featured
hikes.
• 
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.
• View photos from the featured
hike
Black Diamond Mines
Regional Park was, once upon a time, ranch land like much of the east bay (of
course, before that it was populated with Native Americans). When in the 1860s
coal was discovered at this parcel of land just south of Pittsburg, extensive
mining took place, with nearly 4 million tons of "black diamond" removed
from the earth. When coal use dropped off around the turn of the century, the
land was mined for sand. More than 1.8 million tons of the stuff was removed.
In spite of all that has been taken away, Black Diamond Mines is remarkable for
what remains. An over 5,000 acre park, Black Diamond Mines boosts 65 miles of
trails through grassland, chaparral, and oak savannah, and past sandstone rock
formations. If one day at Black Diamond Mines isn't enough, a backpack and separate
group camp make it possible to linger a little longer.
Spring is the optimal time of year for a visit,
although the blue oaks are lovely in autumn, and the manzanitas are stunning in
winter. Springtime brings carpets of flowers, fresh oak leaves, and soft warm
temperatures.
If you wish to learn more about the mining history of Black Diamond Mines, you
can stop by the Underground Mining Museum, and/or hike to the remains of the mines.
Most mine entrances are barred, but bring a flashlight to explore 200 feet of
Prospect Tunnel's 400-foot passage. If you're just interested in the trails, you'll
have plenty to choose from. Short loops originate at the main trailhead, as well
as the park office trailhead, and the entrance at Contra Loma Regional Park. Longer
hikes of 8-10 miles are possible as well. If you visit once and are hooked like
me, you'll have lots of map fun planning your next hike at Black Diamond Mines.
Start at the gate near the information signboard
at the end of the parking lot. Walk uphill on the broad multi-use Nortonville
Trail. At about 250 feet, the trail crests at a signed junction. Turn left
on Stewartville Trail, open to hikers, equestrians, and cyclists. A few steps
later, at about 0.16 mile, you'll reach a signed junction with Railroad Bed Trail.
Continue straight on Stewartville Trail. 
The
grade is initially level, but after passing a junction with the Pittsburg Mine
Trail, Stewartville Trail begins to climb. The trailside grassland hosts owl's
clover, fiddlenecks, and ithuriel's spear in spring. At about 0.55 mile, Stewartville
Trail attains its peak elevation and reaches a signed junction just before a cattle
gate. Turn right on Ridge Trail.
Ridge Trail starts out open to equestrians, cyclists,
and hikers, but a sign warns that there's no outlet for horses and bikes ahead,
as the trail enters a sensitive ecological area where only hikers are permitted.
There are nice views down into the valley to the southeast, and a peak at Mount
Diablo to the west. Ridge Trail climbs for a few feet, then dips down and contours
levelly around a hill. If you're hiking in late winter, you'll likely see Padre's
shooting stars nestled in the grass. Later in spring, lupines, buttercups, and
fiddlenecks are plentiful. Buckeyes and blue oaks pepper the hillsides. On the
left of the trail, look for the delicate white blossoms of woodland star in spring.
On a clear day, views unfold to the right, permitting you to see all the way past
the bay to Solano County. 
Ridge
Trail begin to climb, and passes through a cattle gate. Look on the left for lots
of bluedicks and a few owl's clover in early spring. Continuing to ascend, you
might notice a change in the trailside vegetation. Oaks are still present, but
the manzanitas seem out of place. And these aren't stunted shrubs, but full-size
and even tree-size specimens. This shift in vegetation continues, and you'll reach
a hilltop, at about 1195 feet, with more manzanitas and coulter pines. Also look
for yerba santa and stunning red paintbrush blooming in early spring. On the left,
a bare sandstone ledge provides the perfect rest stop. The view down into the
valley is just incredible. This has to be one of my favorite bay area vistas.
A verdant valley is dotted with ponds, and sheltered on both sides by hills. Chaparral
lines the slopes on the west, while the eastern hills are shaded by oaks. A longer
view to the west reveals the high peaks of Mount Diablo. When I visited on a breezy
spring day, the winds rustled through the coulter pines, and I felt very far area
from the bay area. When you're ready, continue on Ridge Trail, which begins to
descend.
The flowers of winter's Indian warrior give way to the cheerful yellow blossoms
of bush poppy as spring rolls around. Ridge Trail curves to the left away from
a dropoff, revealing sandstone rock formations down the hill. At 1.25 miles, Ridge
Trail ends at a signed junction. Turn right on Chaparral Loop Trail. (Option:
if you want to avoid a descent followed by an ascent, and the crowds around the
park's mining museum, you can continue straight at this junction, on Chaparral
Loop. The mileage will be about the same, but you'll save yourself some energy.)
Sandstone soil, fostering coulter pines, chamise,
and manzanita, make this area of the park distinctive. Chaparral Loop Trail, a
hiking only path, descends gently toward a rock formation. Paintbrush and bush
poppy add color to the bare ground. At 1.32 miles, you'll reach a signed junction
in front of the rock formation (as far as I know it is nameless, though it certainly
deserves a great moniker). Bear left on Lower Chaparral Trail.
Lower Chaparral Trail is also
closed to cyclists and horses. The sandy path loses elevation at an easy pace,
then narrows and drops somewhat steeply through a very rocky stretch. After passing
a path breaking off to the right (not a sanctioned route), Lower Chaparral Trail
edges across a grassy hillside. Look on the left for royal larkspur, woodland
star, and branched phacelia. Poison oak, which had been absent until this part
of the hike, makes an appearance. Lower Chaparral Trail darts into the shade of
coulter pines and manzanita, and ends at a signed junction at 1.59 miles. Bear
left on Chaparral Loop.
Hiking-only Chaparral Loop climbs on a narrow path
through coulter pine, oaks, and manzanita. You'll pass rough paths that ascend
to join Chaparral Loop from the creekbed on the right. At 1.89 miles, Chaparral
Loop Trail meets a signed junction. Bear right (sign reads "to Manhattan
Canyon Trail"). After climbing a few feet, you'll reach another junction,
with Manhattan Canyon Trail. Turn right.
Buckbrush 
and
chamise line the hiking only trail as it climbs. Look to the right, across the
canyon, for views of more rock formations barely concealed by vegetation. At 1.96
miles, there is yet another junction. Manhattan Canyon Trail continues to the
right, but turn left, "to Black Diamond Trail." (By the way,
the last three junctions are really hard to follow with the park's map. It's worthwhile
to write down these directions, or at least be prepared to roll with the punches
if you find yourself off course.)
The narrow hiking only trail skirts the base of
a natural rock wall, through chamise, yerba Santa, sagebrush, and black sage.
In spring you may see mosquito bills blooming in the shade on the right side of
the trail, and fremont's camas tucked under the shrubs. There are nice views back
across the canyon to the southeast, and you may even catch a glimpse of some steps
on Chaparral Loop Trail. At 2.16 miles, the path ends at a signed junction with
Black Diamond Trail. Turn right.
After a short steep climb on multi-use Black Diamond
Trail you'll leave chaparral behind, and enter a lovely oak savannah. In spring,
look for carpets of bluedicks
(they blend into the grass, so they aren't all that obvious considering their
numbers). Black Diamond Trail levels out at a gate, and continues on a mostly
flat course. There are long views, encompassing the journey so far, and through
a notch near Rose Hill to the bay. If you're hiking in late winter, look to the
right for a staggering display of Padre's shooting stars. These white flowers
really stand out in the green grass. Black Diamond Trail begins to descend, passing
under power lines and ending at a signed junction at 2.69 miles. Bear right
onto Nortonville Trail.
Nortonville Trail, open to hikers, equestrians,
and cyclists, descends through grassland. Look for owl's clover, redmaids, and
lupines in the spring. A path to the left departs to visit Rose Hill Cemetery,
an optional side trip. At 3.17 miles, you'll reach a signed junction with one
of the legs of Manhattan Canyon Trail. Continue straight. Nortonville Trail
passes through a cattle gate, and at 3.31 miles, encounters the second leg of
Manhattan Canyon Trail. Continue straight.
Red winged blackbirds are plentiful especially
on the left side of the trail in a marshy area. Descending at a gentle pace, the
trail reaches a signed junction at 3.41 miles, with the most commonly visited
area of the park, the Underground Mining Museum (another optional side trip).
Continue straight on Nortonville Trail, under a few blue oaks, past the
previously encountered junction with Stewardville Trail, and return to the
trailhead.
Total distance: 3.5 miles
Last hiked: Tuesday, March 27, 2001
Go to Bay Area Hiker Home page
Regional Park was, once upon a time, ranch land like much of the east bay (of
course, before that it was populated with Native Americans). When in the 1860s
coal was discovered at this parcel of land just south of Pittsburg, extensive
mining took place, with nearly 4 million tons of "black diamond" removed
from the earth. When coal use dropped off around the turn of the century, the
land was mined for sand. More than 1.8 million tons of the stuff was removed.
In spite of all that has been taken away, Black Diamond Mines is remarkable for
what remains. An over 5,000 acre park, Black Diamond Mines boosts 65 miles of
trails through grassland, chaparral, and oak savannah, and past sandstone rock
formations. If one day at Black Diamond Mines isn't enough, a backpack and separate
group camp make it possible to linger a little longer. 
If you wish to learn more about the mining history of Black Diamond Mines, you
can stop by the Underground Mining Museum, and/or hike to the remains of the mines.
Most mine entrances are barred, but bring a flashlight to explore 200 feet of
Prospect Tunnel's 400-foot passage. If you're just interested in the trails, you'll
have plenty to choose from. Short loops originate at the main trailhead, as well
as the park office trailhead, and the entrance at Contra Loma Regional Park. Longer
hikes of 8-10 miles are possible as well. If you visit once and are hooked like
me, you'll have lots of map fun planning your next hike at Black Diamond Mines.
The
grade is initially level, but after passing a junction with the Pittsburg Mine
Trail, Stewartville Trail begins to climb. The trailside grassland hosts owl's
clover, fiddlenecks, and ithuriel's spear in spring. At about 0.55 mile, Stewartville
Trail attains its peak elevation and reaches a signed junction just before a cattle
gate. Turn right on Ridge Trail.
Ridge
Trail begin to climb, and passes through a cattle gate. Look on the left for lots
of bluedicks and a few owl's clover in early spring. Continuing to ascend, you
might notice a change in the trailside vegetation. Oaks are still present, but
the manzanitas seem out of place. And these aren't stunted shrubs, but full-size
and even tree-size specimens. This shift in vegetation continues, and you'll reach
a hilltop, at about 1195 feet, with more manzanitas and coulter pines. Also look
for yerba santa and stunning red paintbrush blooming in early spring. On the left,
a bare sandstone ledge provides the perfect rest stop. The view down into the
valley is just incredible. This has to be one of my favorite bay area vistas.
A verdant valley is dotted with ponds, and sheltered on both sides by hills. Chaparral
lines the slopes on the west, while the eastern hills are shaded by oaks. A longer
view to the west reveals the high peaks of Mount Diablo. When I visited on a breezy
spring day, the winds rustled through the coulter pines, and I felt very far area
from the bay area. When you're ready, continue on Ridge Trail, which begins to
descend.
The flowers of winter's Indian warrior give way to the cheerful yellow blossoms
of bush poppy as spring rolls around. Ridge Trail curves to the left away from
a dropoff, revealing sandstone rock formations down the hill. At 1.25 miles, Ridge
Trail ends at a signed junction. Turn right on Chaparral Loop Trail. (Option:
if you want to avoid a descent followed by an ascent, and the crowds around the
park's mining museum, you can continue straight at this junction, on Chaparral
Loop. The mileage will be about the same, but you'll save yourself some energy.)
closed to cyclists and horses. The sandy path loses elevation at an easy pace,
then narrows and drops somewhat steeply through a very rocky stretch. After passing
a path breaking off to the right (not a sanctioned route), Lower Chaparral Trail
edges across a grassy hillside. Look on the left for royal larkspur, woodland
star, and branched phacelia. Poison oak, which had been absent until this part
of the hike, makes an appearance. Lower Chaparral Trail darts into the shade of
coulter pines and manzanita, and ends at a signed junction at 1.59 miles. Bear
left on Chaparral Loop. 
and
chamise line the hiking only trail as it climbs. Look to the right, across the
canyon, for views of more rock formations barely concealed by vegetation. At 1.96
miles, there is yet another junction. Manhattan Canyon Trail continues to the
right, but turn left, "to Black Diamond Trail." (By the way,
the last three junctions are really hard to follow with the park's map. It's worthwhile
to write down these directions, or at least be prepared to roll with the punches
if you find yourself off course.)
(they blend into the grass, so they aren't all that obvious considering their
numbers). Black Diamond Trail levels out at a gate, and continues on a mostly
flat course. There are long views, encompassing the journey so far, and through
a notch near Rose Hill to the bay. If you're hiking in late winter, look to the
right for a staggering display of Padre's shooting stars. These white flowers
really stand out in the green grass. Black Diamond Trail begins to descend, passing
under power lines and ending at a signed junction at 2.69 miles. Bear right
onto Nortonville Trail.