The Sweet Oil "diggings" in southwestern Plumas County about eight miles north of La Pone were mined by hydraulicking years ago. The gravel deposits are believed to be located on a branch of the Tertiary La Porte channel. Bedrock is slate, and to the south the gravels are capped by andesite and basalt.
Turner, H.W., 1898, Bidwell Bar folio: U.S. Geol. Survey Geol. Atlas of the U.S., folio 43, 6 pp.