(California)
Malakoff Diggins State Historic Park is a state park unit preserving Malakoff Diggins, the largest hydraulic mining site in California, United States. The mine was one of several hydraulic mining sites at the center of the 1882 landmark case Woodruff v. North Bloomfield Mining and Gravel Company. The mine pit and several Gold Rush-era buildings are listed on the National Register of Historic Places as the Malakoff Diggins-North Bloomfield Historic District. The "canyon" is 7,000 feet (2,100 m) long, as much as 3,000 feet (910 m) wide, and nearly 600 feet (180 m) deep in places. Visitors can see huge cliffs carved by mighty streams of water, results of the mining technique of washing away entire mountains of gravel to wash out the gold. The park is 26 miles (42 km) north-east of Nevada City, California, in the Gold Rush country. The 3,143-acre (1,272 ha) park was established in 1965. (Ref: https://en.wikipedia.org/wiki/Malakoff_Diggins_State_Historic_Park)