Location
This placer-mining district is in northwestern Sierra County and southern Plumas County in the vicinity of the old town of Gibsonville. It is about six miles northeast of La Porte and 20 miles due north of Downieville. The district includes the Whiskey Diggings, Hepsidam, and Bunker Hill areas. The area was first worked during the gold rush, and considerable drift mining and some hydraulic mining followed in 1875-95. There has been intermittent prospecting
Geology
The deposits are located on the Tertiary North Fork of the Yuba River, which is also known as the La Porte channel. The channel extends in a southwest direction through the district. The channel gravels are as much as 1500 feet wide and capped by thick beds of andesite and clay. The gold was found mostly in quartz-rich gravels near bedrock and was mostly coarse-grained. Some ground yielded up to $3 per yard of gold at the old price. There are a number of drops in the channel, caused possibly by bedrock faulting. The bedrock consists of amphibolite with serpentine, slate, and schist lying to the east. The channel has been drift-mined almost continuously from Hepsidam southwest through Gibsonville to the Thistle shaft, a distance of about five miles. Although the district is reported to have had only a moderate output, extensive drifting and a number of rich pay streaks indicate that it must have been much more productive than originally believed.
Mines
Bellevue group, Bunker Hill, Empire, Feather Fork (Thistle), Garnet, Gibsonville Water and Mining (hydraulic), Homestake, Taber (Hal Taber), Union-Keystone $600,000, Washington (North American Cons.) (hydraulic), Whiskey (hydraulic ).
Bibliography
Crawford, J. J., 1896, Feather Fork mine: California Min. Bur. Rept. 13, p. 376.
Lindgren, Waldemar, 1911, Tertiary gravels of the Sierra Nevada: U.S. Geol. Survey Prof. Paper 73, pp. 106-107.
MacBoyle, Errol, 1921, Sierra County, Gibsonville mining district: California Min. Bur. Rept. 17, pp. 11-13.
Turner, H. W., 1897, Downieville folio, California: U. S. Geol. Survey Geol. Atlas of the U. S., folio 37, 8 pp.
Weil, S. C., The ancient channel of Gibsonville: Min. and Sci. Press, vol. 91, July 29, 1905, p. 73.
Wiltsee, E. A., 1893, Gibsonville mining district: California Min. Bur. Rept. 11, pp. 418-419.
