https://en.m.wikipedia.org/wiki/Black_Diamond_Mines_Regional_Preserve
The Black Diamond Mines Regional Preserve is a 6,000-acre (2,400 ha) park located north of Mount Diablo in Contra Costa County, California under the administration of the East Bay Regional Park District(EBRPD). The district acquired the property in 1973. The preserve contains relics of 3 mining towns, former coal and sand mines, and offers guided tours of a former sand mine. The 60 miles (97 km) of trails in the Preserve cross rolling foothill terrain covered with grassland, California oak woodland, California mixed evergreen forest, and chaparral.
The Black Diamond Mines Regional Preserve is a 6,000-acre (2,400 ha) park located north of Mount Diablo in Contra Costa County, California under the administration of the East Bay Regional Park District(EBRPD). The district acquired the property in 1973. The preserve contains relics of 3 mining towns, former coal and sand mines, and offers guided tours of a former sand mine. The 60 miles (97 km) of trails in the Preserve cross rolling foothill terrain covered with grassland, California oak woodland, California mixed evergreen forest, and chaparral.
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Greathouse Portal, Black Diamond Mine Regional Preserve in 2012
Inside the Greathouse portal, a 950 foot (290 m)-long section of the entrance corridor has been made into a museum. The first section is a series of self-guided exhibits, while the larger second section (which has a separate entrance from the outside), houses a reconstruction of the Hazel-Atlas works as it would have appeared around 1940.[19]
EBRPD originally repurposed the Hazel-Atlas mine as a museum in the 1970s, but storm damage in 2007 forced closure of this attraction for extensive repairs. It did not reopen for five years.[20]
Portal ???
Mines = Tunnels
Inside the Greathouse portal, a 950 foot (290 m)-long section of the entrance corridor has been made into a museum. The first section is a series of self-guided exhibits, while the larger second section (which has a separate entrance from the outside), houses a reconstruction of the Hazel-Atlas works as it would have appeared around 1940.[19]
EBRPD originally repurposed the Hazel-Atlas mine as a museum in the 1970s, but storm damage in 2007 forced closure of this attraction for extensive repairs. It did not reopen for five years.[20]
Portal ???
Mines = Tunnels
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