Geologic units in Merced county, California

Quaternary alluvium and marine deposits (Pleistocene to Holocene) at surface, covers 54 % of this area

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

Plio-Pleistocene and Pliocene loosely consolidated deposits (Miocene to Pleistocene) at surface, covers 11 % of this area

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

Quaternary sand deposits, unit 2 (inland) (Quaternary) at surface, covers 10 % of this area

Extensive marine and nonmarine sand deposits, generally near the coast or desert playas

Upper Cretaceous marine rocks, unit 1 (Upper Great Valley Sequence) (Late Cretaceous) at surface, covers 8 % of this area

Upper Cretaceous sandstone, shale, and conglomerate

Franciscan Complex, unit 1 (Coast Ranges) (Jurassic to Cretaceous) at surface, covers 6 % of this area

Franciscan complex: Cretaceous and Jurassic sandstone with smaller amounts of shale, chert, limestone, and conglomerate. Includes Franciscan melange, except where separated--see KJfm.

Miocene nonmarine rocks (Oligocene to Pleistocene) at surface, covers 3 % of this area

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

Older Quaternary alluvium and marine deposits (Pleistocene) at surface, covers 2 % of this area

Older alluvium, lake, playa, and terrace deposits.

Tertiary volcanic flow rocks, unit 1 (Quien Sabe-Burdell Mountain) (Tertiary (9.5-13 Ma)) at surface, covers 2 % of this area

Tertiary volcanic flow rocks; minor pyroclastic deposits.

Franciscan melange (Jurassic to Cretaceous) at surface, covers 1 % of this area

Melange of fragmented and sheared Franciscan complex rocks.

Eocene nonmarine rocks, unit 1 (Northern and Central California) (Eocene) at surface, covers 1.0 % 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 0.4 % of this area

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

Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains) (Jurassic) at surface, covers 0.3 % 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.

Paleocene marine rocks, unit 1 (Central and Southern California) (Paleocene) at surface, covers 0.2 % of this area

Sandstone, shale, and conglomerate; mostly well consolidated

Ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains) (Middle to Late Jurassic) at surface, covers 0.2 % of this area

Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase. Chiefly Mesozoic unit 3

Tertiary intrusive rocks (hypabyssal), unit 2 (Quien Sabe Volcanic Field) (Tertiary) at surface, covers 0.2 % of this area

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

Mesozoic volcanic rocks, unit 1 (Coast Ranges) (Jurassic to Cretaceous) at surface, covers 0.1 % of this area

pre-Cenozoic granitic and metamorphic rocks undivided (Early Proterozoic to Late Cretaceous) at surface, covers < 0.1 % of this area

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

Eocene marine rocks (Paleocene to Oligocene) at surface, covers < 0.1 % of this area

Shale, sandstone, conglomerate, and minor limestone; in part Oligocene and Paleocene.

Miocene marine rocks (Oligocene to Pliocene) at surface, covers < 0.1 % of this area

Sandstone, shale, siltstone, conglomerate and breccia; in part Pliocene and Oligocene.

Tertiary volcanic flow rocks, unit 5 (San Luis Reservoir) (Tertiary (7.5-9.5 Ma)) at surface, covers < 0.1 % of this area

Tertiary volcanic flow rocks; minor pyroclastic deposits.

Franciscan schist (Early Cretaceous) at surface, covers < 0.1 % of this area

Blueschist and semi-schist of Franciscan complex

Lower Cretaceous marine rocks (Early Cretaceous) at surface, covers < 0.1 % of this area

Lower Cretaceous sandstone, shale, and conglomerate