Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > California Geology
Geologic units in San Francisco county, California
- Upper Cretaceous marine rocks, unit 1 (Upper Great Valley Sequence) (Late Cretaceous) at surface, covers 2 % of this area
Upper Cretaceous sandstone, shale, and conglomerate
- Franciscan Complex, unit 1 (Coast Ranges) (Jurassic to Cretaceous) at surface, covers 19 % 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.
- Pliocene marine rocks (Miocene to Pleistocene) at surface, covers < 0.1 % of this area
Sandstone, siltstone, shale, and conglomerate; in part Pleistocene and Miocene.
- Mesozoic granitic rocks, unit 1 (Salinian Block) (Early to Late Cretaceous) at surface, covers < 0.1 % of this area
Mesozoic granite, quartz monzonite, granodiorite, and quartz diorite
- Quaternary alluvium and marine deposits (Pliocene to Holocene) at surface, covers 25 % of this area
Alluvium, lake, playa, and terrace deposits; unconsolidated and semi-consolidated. Mostly nonmarine, but includes marine deposits near the coast.
- Franciscan melange (Jurassic to Cretaceous) at surface, covers 0.3 % of this area
Melange of fragmented and sheared Franciscan complex rocks.
- Quaternary sand deposits, unit 1 (coastal) (Quaternary) at surface, covers 39 % of this area
Extensive marine and nonmarine sand deposits, generally near the coast or desert playas
- Mesozoic volcanic rocks, unit 1 (Coast Ranges) (Jurassic to Cretaceous) 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
- Ultramafic rocks, chiefly Mesozoic, unit 3 (Coast Ranges and Western Klamath Mountains) (Middle to Late Jurassic) at surface, covers 5 % of this area
Ultramafic rocks, mostly serpentine. Minor peridotite, gabbro, and diabase. Chiefly Mesozoic unit 3