Black Diamond Mines Regional Preserve between Mt. Diablo and the west delta

The Black Diamond Mines Regional Preserve has between 45 and 65 miles of trails, depending on which source you are consulting and how you measure the length of those trails that wind up steep slopes. There are hiking-only trails and horse and bicycle trails. Many trails are also frequented or crossed by cows. The preserve features a dense trail network, well-marked with signposts, inviting hikers to loop around and access the different park features including places and artifacts from the coal mining days between about 1860 and 1900, when this was the Mt. Diablo Coal Field. The mining towns Nortonville, Somersville and Stewartsville were within the current preserve boundaries. Nortonville, founded by Noah Norton in 1861, was the largest. An information board at the Nortonville Townsite, west of the Rose Hill Cemetery, says that more than 1,000 residents were living just in that town at the peak of mining activity. Then, the town boasted a public school, a hotel, stores, churches, fraternal halls, and saloons. The town is gone, but the mining bonanza left some marks between riparian habitats and often steep hills covered by grassland, chaparral, or mixed evergreen forest.

Getting there
From Oakland, California, drive east on Highway 24. In Walnut Creek go north on Interstate 680 and take the connector 242 through Concord to Highway 4. Drive east on Highway 4. Pass Pittsburg and take the Somersville Road exit in Antioch. Go south on Somersville Road. Follow this road through the residential area and drive into the hills until you get to the park entrance. After passing the gate you will find a parking lot on the left side. There are the park office, a small visitor center, and interpretive boards. You can access the trail network here or from another parking and picnic area that is located further south, less than a mile away. This second trailhead is the gateway to the Greathouse Visitor Center (closed during 2009 and 2010) and mining features such as the Hazel Atlas Portal, various shafts, mines and tunnels. From here you can get on the Nortonville Trail, Stewartville Trail, Manhattan Canyon Trail and other trails, paths and loops.

Resources
[1] East Bay Regional Park District: Black Diamond Mines Regional Preserve.
[2] David Weintraub: East Bay Trails. Wilderness Press, Berkeley, 1998.