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Mineral Resources > Online Spatial Data > Geology > by state > California Geology

Geologic units in Mendocino county, California

[Additional scientific data in this geographic area]

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

Upper Cretaceous sandstone, shale, and conglomerate

Lithology: sandstone; mudstone; conglomerate

Franciscan Complex, unit 1 (Coast Ranges) (Jurassic to Cretaceous) at surface, covers 34 % 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.

Lithology: sandstone; mudstone; chert; limestone; conglomerate; greenstone; serpentinite; gabbro; amphibolite; schist; felsic volcanic rock

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.

Lithology: sandstone; conglomerate; claystone; shale; siltstone; limestone; evaporite; coal; sedimentary breccia

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

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

Lithology: sandstone; mudstone; siltstone; claystone; conglomerate

Eocene and Paleocene marine rocks, undivided (Paleocene to middle Eocene) at surface, covers 0.3 % of this area

Lithology: sandstone; mudstone; conglomerate

Lower Cretaceous marine rocks (Early Cretaceous) at surface, covers 0.2 % of this area

Lower Cretaceous sandstone, shale, and conglomerate

Lithology: mudstone; sandstone; conglomerate

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

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.

Lithology: alluvium; terrace; lake or marine deposit (non-glacial)

Franciscan schist (Early Cretaceous) at surface, covers 5 % of this area

Blueschist and semi-schist of Franciscan complex

Lithology: blueschist; metasedimentary rock; metavolcanic rock

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

Tertiary-Cretaceous Coastal Belt Rocks (Late Cretaceous to Pliocene) at surface, covers 45 % of this area

Sandstone, shale and minor conglomerate in coastal belt of northwestern California; included by some in Franciscan Complex. Previously considered Cretaceous, but now known to contain early Tertiary microfossils in places.

Lithology: sandstone; mudstone; conglomerate; basalt; limestone; blueschist; chert

Eocene marine rocks (Paleocene to Oligocene) at surface, covers 0.6 % of this area

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

Lithology: mudstone; sandstone; conglomerate; limestone; siltstone; sedimentary breccia

Quaternary sand deposits, unit 1 (coastal) (Quaternary) at surface, covers < 0.1 % of this area

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

Lithology: dune sand; beach sand

Cretaceous marine rocks (in part nonmarine), unit 1 (Coast Ranges) (Early to Late Cretaceous) at surface, covers 0.1 % of this area

Undivided Cretaceous sandstone, shale, and conglomerate; minor nonmarine rocks in Peninsular Ranges

Lithology: mudstone; sandstone; conglomerate

Paleocene marine rocks, unit 1 (Central and Southern California) (Paleocene) at surface, covers < 0.1 % of this area

Sandstone, shale, and conglomerate; mostly well consolidated

Lithology: sandstone; mudstone; conglomerate

Franciscan melange (Jurassic to Cretaceous) at surface, covers 4 % of this area

Melange of fragmented and sheared Franciscan complex rocks.

Lithology: melange

Ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains) (Middle to Late Jurassic) at surface, covers 2 % of this area

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

Lithology: serpentinite; peridotite

Miocene marine rocks (Oligocene to Pliocene) at surface, covers 0.7 % of this area

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

Lithology: sandstone; mudstone; siltstone; evaporite; conglomerate

Paleocene marine rocks, unit 2 (Northern California) (Paleocene to late Eocene) at surface, covers 0.6 % of this area

Sandstone, shale, and conglomerate; mostly well consolidated

Lithology: mudstone; sandstone; conglomerate

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

Lithology: greenstone; basalt; diabase; blueschist; chert; felsic volcanic rock