This district is in northwestern Nevada County nine miles northwest of Nevada City. It consists of the placer deposits that extend from the vicinity of North San Juan southwest for about 2.5 miles to the Sweetland area. It was named for a nearby hill with the "North" added to distinguish it from San Juan (now San Juan Bautista) in San Benito County.
A main Tertiary channel of the Yuba River extends into the area from the Badger Hill and North Columbia districts from the east and another from Camptonville from the northwest. The channel then extends southwest through Sweetland into the French Corral district. The gravels are 150 to 400 feet thick and up to 1000 feet wide. The low gravels yielded up to 30Â¢ per yard in gold, mostly from hydraulicking. The bedrock is granodiorite with amphibolite to the west. There are several narrow gold-quartz veins in the amphihplite.
Lindgren, Waldemar, 1895, Smartsville folio, California: U. S. Geol. Survey Geol. Atlas of the U.S., folio 18, 6 pp.
Lindgren, Waldemar, 1911, Tertiary gravels of the Sierra Nevada: U.S. Geol. Survey Prof. Paper 73, pp. 121-125.
MacBoyle, Errol, 1919, Nevada County, North San Juan mining district: California Min. Bur. Rept. 16, pp. 51-54.