Geologic units in Plumas county, California

Tertiary pyroclastic and volcanic mudflow deposits, unit 9 (Cascade Range) (Tertiary (2-24 Ma)) at surface, covers 18 % of this area

Tertiary pyroclastic and volcanic mudflow deposits.

Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges) (Permian to Tertiary; most Mesozoic) at surface, covers 17 % of this area

Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite

Tertiary volcanic flow rocks, unit 17 (Cascade Range) (Tertiary (2-24 Ma)) at surface, covers 16 % of this area

Tertiary volcanic flow rocks; minor pyroclastic deposits.

Quaternary alluvium and marine deposits (Pleistocene to Holocene) at surface, covers 10 % of this area

Alluvium, lake, playa, and terrace deposits; unconsolidated and semi-consolidated. Mostly nonmarine, but includes marine deposits near the coast.

Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada) (Ordovician to Triassic) at surface, covers 8 % of this area

Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite

Paleozoic metavolcanic rocks, unit 2 (Northeastern Sierra Nevada) (Devonian and Permian) at surface, covers 6 % of this area

Undivided Paleozoic metavolcanic rocks. Mostly flows, breccia and tuff, including greenstone, diabase, and pillow lavas; minor interbedded sedimentary rocks

Ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains) (Late Proterozoic(?) to Early Jurassic) at surface, covers 3 % of this area

Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase. Chiefly Mesozoic unit 2

Quaternary volcanic flow rocks, unit 1 (Cascade Volcanic Field) (Quaternary) at surface, covers 3 % of this area

Quaternary volcanic flow rocks; minor pyroclastic deposits; in part Pliocene and Miocene.

Paleozoic marine rocks, undivided, unit 6 (Northwestern Sierra Nevada) (Permian(?) to Jurassic(?)) at surface, covers 3 % of this area

Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite

Paleozoic metavolcanic rocks, unit 3 (Northwestern Sierra Nevada) (Permian to Jurassic) at surface, covers 3 % of this area

Undivided Paleozoic metavolcanic rocks. Mostly flows, breccia and tuff, including greenstone, diabase, and pillow lavas; minor interbedded sedimentary rocks

Mesozoic volcanic rocks, unit 5 (Northern Sierra Nevada and Eastern Klamath Mountains) (Late Permian(?) to Jurassic) at surface, covers 2 % of this area

Undivided Mesozoic volcanic and metavolcanic rocks. Andesite and rhyolite flow rocks, greenstone, volcanic breccia and other pyroclastic rocks; in part strongly metamorphosed. Includes volcanic rocks of Franciscan Complex: basaltic pillow lava, diabase, greenstone, and minor pyroclastic rocks.

Undivided pre-Cenozoic metavolcanic rocks, unit 2 (undivided) (Paleozoic(?) to Mesozoic(?)) at surface, covers 2 % of this area

Undivided pre-Cenozoic metavolcanic rocks. Includes latite, dacite, tuff, and greenstone; commonly schistose.

Triassic marine rocks, unit 3 (Lake Almanor) (Permian to Jurassic) at surface, covers 2 % of this area

Shale, conglomerate, limestone and dolomite, sandstone, slate, hornfels, quartzite; minor pyroclastic rocks

Paleozoic marine rocks, undivided, unit 5 (Northeastern Sierra Nevada) (Ordovician to Jurassic) at surface, covers 1 % of this area

Undivided Paleozoic metasedimentary rocks. Includes slate, sandstone, shale, chert, conglomerate, limestone, dolomite, marble, phyllite, schist, hornfels, and quartzite

Quaternary glacial deposits (Pleistocene) at surface, covers 1 % of this area

Glacial till and moraines. Found at high elevations mostly in the Sierra Nevada and Klamath Mountains.

Permian marine sedimentary rocks, unit 3 (Northeastern Sierra Nevada) (Early to Late Permian) at surface, covers 0.9 % of this area

Shale, conglomerate, limestone and dolomite, sandstone, slate, hornfels, quartzite; minor pyroclastic rocks

Jurassic marine rocks, unit 5 (Northern Sierra Nevada and Eastern Klamath Mountains) (Devonian to Late Jurassic) at surface, covers 0.8 % of this area

Shale, sandstone, minor conglomerate, chert, slate, limestone; minor pyroclastic rocks

Eocene nonmarine rocks, unit 1 (Northern and Central California) (Eocene) at surface, covers 0.7 % of this area

Sandstone, shale, and conglomerate.

Older Quaternary alluvium and marine deposits (Pleistocene) at surface, covers 0.6 % of this area

Older alluvium, lake, playa, and terrace deposits.

Mesozoic gabbroic rocks, unit 2 (undivided) (Triassic to Cretaceous) at surface, covers 0.3 % of this area

Gabbro and dark dioritic rocks; chiefly Mesozoic

Permian marine sedimentary rocks, unit 2 (Northwestern Sierra Nevada) (Paleozoic or Mesozoic) at surface, covers 0.3 % of this area

Shale, conglomerate, limestone and dolomite, sandstone, slate, hornfels, quartzite; minor pyroclastic rocks

Carboniferous marine rocks, unit 6 (Northeastern Sierra Nevada) (Mississippian to Early Permian) at surface, covers 0.3 % of this area

Shale, sandstone, conglomerate, limestone, dolomite, chert, hornfels, marble, quartzite; in part pyroclastic rocks

Mesozoic granitic rocks, unit 4 (Klamath Mountains and Northern Sierra Nevada) (Devonian) at surface, covers 0.2 % of this area

Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite

Tertiary nonmarine rocks, undivided (Paleocene to Pliocene) at surface, covers 0.1 % of this area

Undivided Tertiary sandstone, shale, conglomerate, breccia, and ancient lake deposits.

Tertiary intrusive rocks (hypabyssal), unit 1 (Cascades Volcanic Field) (Tertiary) at surface, covers 0.1 % of this area

Tertiary intrusive rocks; mostly shallow (hypabyssal) plugs and dikes. Includes some Mesozoic rocks.

Silurian and/or Ordovician marine rocks, unit 4 (Northern Sierra Nevada) (Ordovician to Devonian) at surface, covers 0.1 % of this area

Sandstone, shale, conglomerate, chert, slate, quartzite, hornfels, marble, dolomite, phyllite; some greenstone

pre-Cenozoic metasedimentary and metavolcanic rocks undivided (Early Proterozoic to Cretaceous) at surface, covers 0.1 % of this area

Undivided pre-Cenozoic metasedimentary and metavolcanic rocks of great variety. Mostly slate, quartzite, hornfels, chert, phyllite, mylonite, schist, gneiss, and minor marble.

Triassic marine rocks, unit 5 (Northern Sierra Nevada) (Middle to Late Triassic) at surface, covers < 0.1 % of this area

Shale, conglomerate, limestone and dolomite, sandstone, slate, hornfels, quartzite; minor pyroclastic rocks