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Geologic units in Monterey county, California

Additional scientific data in this geographic area

Plio-Pleistocene and Pliocene loosely consolidated deposits (Miocene to Pleistocene) at surface, covers 22 % of this area

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

pre-Cenozoic metasedimentary and metavolcanic rocks undivided (Early Proterozoic to Cretaceous) at surface, covers 15 % 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.

Mesozoic granitic rocks, unit 1 (Salinian Block) (Early to Late Cretaceous) at surface, covers 15 % of this area

Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite

Miocene marine rocks (Oligocene to Pliocene) at surface, covers 9 % of this area

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

Franciscan Complex, unit 1 (Coast Ranges) (Jurassic to Cretaceous) at surface, covers 9 % 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.

pre-Cenozoic granitic and metamorphic rocks undivided (Early Proterozoic to Late Cretaceous) at surface, covers 6 % of this area

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

Upper Cretaceous and Paleocene marine rocks, undivided (Late Cretaceous to Paleocene) at surface, covers 5 % of this area

Sandstone, shale, and conglomerate

Quaternary alluvium and marine deposits (Pliocene to Holocene) at surface, covers 4 % of this area

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

Upper Cretaceous marine rocks, unit 1 (Upper Great Valley Sequence) (Late Cretaceous) at surface, covers 3 % of this area

Upper Cretaceous sandstone, shale, and conglomerate

Pliocene marine rocks (Miocene to Pleistocene) at surface, covers 3 % of this area

Sandstone, siltstone, shale, and conglomerate; in part Pleistocene and Miocene.

Quaternary sand deposits, unit 1 (coastal) (Quaternary) at surface, covers 2 % of this area

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

Lithology: dune sand; beach sand

Ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains) (Middle to Late Jurassic) at surface, covers 1 % of this area

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

Eocene marine rocks (Paleocene to Oligocene) at surface, covers 1 % of this area

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

Paleocene marine rocks, unit 1 (Central and Southern California) (Paleocene) at surface, covers 1.0 % of this area

Sandstone, shale, and conglomerate; mostly well consolidated

Miocene nonmarine rocks (Oligocene to Pleistocene) at surface, covers 0.9 % of this area

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

Limestone of probable Paleozoic or Mesozoic age (Paleozoic to Mesozoic) at surface, covers 0.5 % of this area

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

Schist of various types and ages, unit 2 (Southern and West-central California) (Late Cretaceous to Eocene) at surface, covers 0.5 % of this area

Schists of various types; mostly Paleozoic or Mesozoic age; some Precambrian.

Lower Cretaceous marine rocks (Early Cretaceous) at surface, covers 0.4 % of this area

Lower Cretaceous sandstone, shale, and conglomerate

Oligocene nonmarine rocks, unit 2 (Central and Southern California) (middle Eocene to early Miocene) at surface, covers 0.3 % of this area

Sandstone, shale, and conglomerate; in part Miocene and Eocene.

Tertiary volcanic flow rocks, unit 2 (Pinnacles-Neenach) (Tertiary (22-24 Ma)) at surface, covers 0.2 % of this area

Tertiary volcanic flow rocks; minor pyroclastic deposits.

Oligocene marine rocks (Eocene to Miocene) at surface, covers 0.2 % of this area

Sandstone, shale, and conglomerate; in part Miocene and Eocene.

Quaternary large landslide deposits (Quaternary) at surface, covers < 0.1 % of this area

Selected large landslides, such as Blackhawk slide on north side of San Gabriel Mountains; early to late Quaternary.

Lithology: landslide

Franciscan melange (Jurassic to Cretaceous) at surface, covers < 0.1 % of this area

Melange of fragmented and sheared Franciscan complex rocks.

Lithology: melange

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

Tertiary pyroclastic and volcanic mudflow deposits, unit 3 (Pinnacles-Neenach) (Tertiary (22-24 Ma)) at surface, covers < 0.1 % of this area

Tertiary pyroclastic and volcanic mudflow deposits.

Tertiary intrusive rocks (hypabyssal), unit 3 (Pinnacles Volcanic Field) (Tertiary) at surface, covers < 0.1 % of this area

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

Lithology: rhyolite

Mesozoic gabbroic rocks, unit 2 (undivided) (Triassic to Cretaceous) at surface, covers < 0.1 % of this area

Gabbro and dark dioritic rocks; chiefly Mesozoic

Lithology: gabbro; diorite

Tertiary volcanic flow rocks, unit 6 (Page Mill-Mindego) (Tertiary (12-15 Ma)) at surface, covers < 0.1 % of this area

Tertiary volcanic flow rocks; minor pyroclastic deposits.

Lithology: basalt; andesite; dacite

Jurassic marine rocks, unit 2 (Coast Ranges) (Late Jurassic to Early Cretaceous) at surface, covers < 0.1 % of this area

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