Geologic units in Amador county, California

Additional scientific data in this geographic area

Tertiary pyroclastic and volcanic mudflow deposits, unit 9 (Cascade Range) (Tertiary (2-24 Ma)) at surface, covers 27 % of this area

Tertiary pyroclastic and volcanic mudflow deposits.

Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains) (Jurassic) at surface, covers 16 % 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

Eocene nonmarine rocks, unit 1 (Northern and Central California) (Eocene) at surface, covers 14 % of this area

Sandstone, shale, and conglomerate.

Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains) (Triassic to Late Jurassic) at surface, covers 11 % of this area

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

Miocene nonmarine rocks (Oligocene to Pleistocene) at surface, covers 10 % of this area

Sandstone, shale, conglomerate, and fanglomerate; in part Pliocene and Oligocene.

Paleozoic marine rocks, undivided, unit 4 (Western Sierra Nevada) (Ordovician to Triassic) at surface, covers 6 % of this area

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

pre-Cenozoic granitic and metamorphic rocks undivided (Early Proterozoic to Late Cretaceous) at surface, covers 3 % of this area

Granitic and metamorphic rocks, mostly gneiss and other metamorphic rocks injected by granitic rocks. Mesozoic to Precambrian.

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 glacial deposits (Pleistocene) at surface, covers 0.9 % of this area

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

Lithology: glacial drift

Plio-Pleistocene and Pliocene loosely consolidated deposits (Miocene to Pleistocene) at surface, covers 0.9 % of this area

Pliocene and/or Pleistocene sandstone, shale, and gravel deposits; in part Miocene.

Paleozoic metavolcanic rocks, unit 4 (Western Sierra Nevada Foothills) (Paleozoic or Mesozoic) at surface, covers 0.6 % of this area

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

Lithology: metavolcanic rock

Mesozoic gabbroic rocks, unit 2 (undivided) (Triassic to Cretaceous) at surface, covers 0.5 % of this area

Gabbro and dark dioritic rocks; chiefly Mesozoic

Lithology: gabbro; diorite

Limestone of probable Paleozoic or Mesozoic age (Paleozoic to Mesozoic) at surface, covers 0.4 % of this area

Limestone, dolomite, and marble whose age is uncertain but probably Paleozoic or Mesozoic