The East Bay Regional Park District began acquiring land for Black Diamond Mines Regional Preserve in the early 1970s. Today, most of the mining district is within the Preserve's nearly 6,096 acres. The area is an ideal location for hiking, picnicking and nature study. Naturalists conduct a variety of programs relating the Preserve's natural and historic resources.
Very little shade. You will be out in the sun for most of it. The cave is not a part of the highlighted trail. Make sure you take the detour to go see it. A good portion of the trail is walking along dirt roads. There is a lot of inclines but they lead to beautiful views of the rolling hills and parts of the surrounding city. Worth checking out. Bring extra water.
Good winter and spring trail especially if you like to hike with your dogs. You might even see a coyote or two. Some nice climbs for a decent. The great thing about the area is it also hooks up with the Mt Diablo trail system which in turn hooks up with a couple of more so you can hike any mileage you want in the area.
I started at the Nortonville Trail, continued onto the Black Diamond Trail, I followed the Black Diamond Trail and completed the loop. Total distance was 5.4 miles, 1,227 feet elevation. Most trails were wide and easy graded except the last couple miles were single track. I enjoyed reading all of signs that showing the historical local coal mining. I also enjoyed views of the surrounding area.
I really liked this trail. I would suggest starting out the trail going to the left. Once you get to the miners trail it was super steep and challenging. Easiest way is to make sure you have room if hiking with others and run or dart up these parts...forward momentum really worked for me. All of the other parts are at a steady incline up. Make sure to take water with you even though it is a short trail it was pretty hot out there and wear sunscreen. Even though I had some on I still got slightly sun burnt. Was really fun and will be doing this trail again.
Nice hike with beautiful views once you reach the top. The first half of the hike, to about the 2.5 mile mark, is steep but once halfway it's mostly downhill from there. Go early in the morning, especially in the summer months, to avoid the heat and bring plenty of water.
I did most of this trail as a part of the "9.4 mile" hike from the Black Diamond main page on ebparks.org. You start on Stewartville, to Star Mine, to Lower Oil Canyon/Oil Canyon/Upper Oil Canyon and finally you have the option to ascend 0.3 miles to the lookout point. Highly recommended.