By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Siskiyou County is one of the three northernmost counties of California. Most of the gold mined in this county has been from placers, the largest of which are along the Salmon, Scott, and Klamath Rivers. Considerable production also came from scattered lode deposits in the Humbug, Yreka, Fort Jones, Cherry Creek, and Cottonwood areas.
Total production of individual districts could not be determined, and the production for the districts is estimated by the authors, on the basis of the sparse published data for the county. Gold production of Siskiyou County from 1880 through 1959 was 1,773,000 ounces.
The east half of the county is underlain by Quaternary volcanic rocks, Pleistocene lake beds, Recent alluvium, and scattered patches of marine sandstone of the Upper Cretaceous Chico Formation. The west half is underlain by interbedded sedimentary and volcanic rocks of Devonian and Carboniferous age. These are severely folded and faulted and are cut by bodies of granodiorite, gabbro, and peridotite of Late Jurassic or Early Cretaceous age (O'Brien, 1947, p. 415).
Throughout Cretaceous time the western part of Siskiyou County was an island and is devoid of any marine sediments of Cretaceous age or later (Averill, 1935, p. 257).
COTTONWOOD-FORT JONES-YREKA DISTRICT
The Cottonwood-Fort Jones-Yreka district is a large area extending from T. 43 to T. 47 N. and from R. 6 to R. 9 W.
Much of it is covered by basal beds of the Upper Cretaceous Chico Formation which unconformably overlie the undifferentiated Paleozoic sequence of shale, slate, sandstone, and limestone. Some of the Cretaceous beds contain coal; others that are conglomeratic indicate proximity to the Cretaceous island of western Siskiyou County (Averill, 1935, p. 258). The conglomerates are auriferous, and reworking of these by recent streams such as Cottonwood and Rancheria Creeks formed placers that yielded about $4 million in gold in the 1850's (Dunn, 1894, p. 466).
The gold in the conglomerate was no doubt eroded from the quartz veins that transect the Paleozoic rocks. The early lode production of this district could not be ascertained; however, the magnitude of operations is indicated by O'Brien (1947, p. 437), who stated that the Golden Eagle mine produced $1 million (about 48,500 ounces) in gold before 1931.
The Humbug district, in T. 46 N., Rs. 10 and 11 W., has been chiefly a lode district, although placers were productive before 1900. Total production through 1959 probably was between 25,000 and 50,000 ounces.
Bedrock in this district consists of metasediments, serpentine, diorite, and diabase of Cambrian to Carboniferous age (Averill, 1935, p. 257-258). Most of these rocks are schistose, and the principal veins are concordant with the schistosity. Some ore is also found in serpentine. No additional information could be found on this district.
KLAMATH RIVER DISTRICT
The Klamath River district is a large area along the Klamath River in the northwest part of Siskiyou County.
In the early days there was considerable hydraulicking of the Quaternary gravels of the Klamath River and its tributaries, and Averill (1935, p. 259) noted that many unworked terrace deposits still remained in the district.
Gold-quartz veins have been productive at scattered localities, particularly at the Independence mine south of Happy Camp, and in recent years lode production exceeded placer production. From 1933 through 1959 the district produced 53,619 ounces of lode gold and 140,364 ounces from placers. No record could be found of earlier production.
SALMON RIVER DISTRICT
The Salmon River district, an area of about 800 square miles, includes most of the drainage of the Salmon River.
The Quaternary placers between Sawyers Bar and Forks of Salmon have produced an estimated $25 million in gold (Averill, 1935, p. 260) and therefore made this district the most productive in Siskiyou County. Lode deposits have also been developed in the district but their early production is not known. From 1932 through 1959 the district was credited with 18,868 ounces of lode gold and 15,981 ounces from placers. No information on the geology of this district could be found.
SCOTT RIVER DISTRICT
The Scott River district, a poorly defined area, is centered around the town of Callahan and extends north along the Scott River.
In the early days there was considerable placer activity near Callahan and at Scott Bar (Averill, 1935, p. 257), and lode mines were also highly productive. Although the early placer production is not known, an incomplete record of lode production was found. The Black Bear mine produced $3,100,000 (about 150,500 ounces) in gold, and the McKeen mine, $250,000 (about 12,100 ounces) (O'Brien, 1947, p. 429, 447).
The most abundant country rock in the district is an undifferentiated sequence of Paleozoic or pre-Paleozoic shales, slates, limestones, and calcareous sandstones. This sequence of rocks was intruded by masses of serpentine and then by gabbro and grancdiorite, all of unknown age (Averill, 1931, p. 8-9, 18, 21-22). No details on the nature of the lodes could be found.
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