Geology
Recent stream gravels lie in and adjacent to the present American River. To the south are sand and gravel deposits of the Victor Formation (Pleistocene) and silt, sand and some gravel of the Laguna Formation (Plio-Pleistocene). These ate underlain by andesite of the Mehrten Formation (Pliocene). The paying gravels are either in or along the American River and near the lower contacts of the Laguna and Mehrten Formations. Digging depths ranged from 30 to 110 feet and recoveries from 10° to 20° per yard with gold valued at $35 per ounce. Minor amounts of platinum were recovered. There are a few narrow gold-quartz veins in greenstone east of the town of Folsom.
Dredging Operations
Capitol Dredging Co., 1927- 52, four bucket-lines; General Dredging Co., 1938-51, three draglines; Gold Hill Dredging Co., 1933-37, one bucket-line; Lancha Plana Gold Dredging Co., 1940- 49, one bucket-line. Natomas Co., 1909-62, fifteen bucket-lines; consolidated by Natomas Co. in 1908 were: Colorado Pacific Gold Dredging Co., El Dorado Gold Dredging Co., Folsom Development Co., Natoma Development Co., Syndicate Gold Dredging Co., Wilkes-Barre Dredging Co. (1916); later Natomas Co. production records, 1959, 7,894,592 cu. yds., 10.19°/yd. yield, 9.56° cost per yard and 1958, 9.15°/yd. yield, 8.73 ° cost per yard.
Bibliography
Carison, D. W., 1955, Sacramento County placer mines, California Jour. Mines and Geology, vol. 51, pp. 134-142.
Crawford, J. J.t 1896, Folsom district: California Min. Bur. Rept. 13, pp.316-317.
Doolittle, J. E., 1905, Folsom district: California Min. Bur. Bull. 36, pp. 92-98.
Lindgren, Waldemar, 1894, Sacramento folio, California: U. S. Geol. Survey Geol. Atlas of the U. S., folio 5, 3 pp.
Lindgren, Waldemar, 1911, Tertiary gravels of the Sierra Nevada, Folsom dredge fields: U. S. Geol. Survey Prof. Paper 73, p. 222. logan, C. A., 1925, Sacramenta County, Dredging: California Min. Bur. Rept. 21, pp. 12-14.
Waring, C. A., 1919, Gold dredging-Sacramento County: California Min. Bur. Rept. 15, pp. 405-415.
Winston, W. B., 1910, Gold dredging in California, Sacramento County, dredging: California Min. Bur. Bull. 57, pp. 176-204.
