| Sespe Formation | |
|---|---|
| Stratigraphic range: Late Eocene-Early Miocene | |
 Weathered, poorly sorted conglomerate from the lower member of the Sespe Formation, Santa Ynez Mountains, California. The clasts range in size from boulders to small pebbles. | |
| Type | sedimentary |
| Underlies | Vaqueros Formation, Monterey Formation |
| Overlies | Coldwater Formation ("Coldwater Sandstone", "Coldwater Shale") |
| Thickness | 0–7,500 ft (0–2,286 m)[1] |
| Lithology | |
| Primary | Sandstone, conglomerate |
| Other | Mudstone, occasional shale |
| Location | |
| Region | Southern and south central California |
| Country |  United States |
| Type section | |
| Named for | Sespe Creek |
| Named by | Watts (1897); redefined by Kew (1924)[2] |
The Sespe Formation is a widespread fossiliferous sedimentary geologic unit in southern and south central California in the United States. It is of nonmarine origin, consisting predominantly of sandstones and conglomerates laid down in a riverine, shoreline, and floodplain environment between the upper Eocene Epoch (around 40 million years ago) through the lower Miocene.[3][4] It is often distinctive in appearance, with its sandstones weathering to reddish-brown, maroon, pinkish-gray, tan, and green. Since many of its sandstones are more resistant to erosion than many other regional sedimentary units it often forms dramatic outcrops and ridgelines in many local mountain ranges.[5][6]
- ^ James M. Galloway. "Santa Barbara-Ventura Basin Province."[permanent dead link] 97.
- ^ Dibblee, Thomas. Geology of the central Santa Ynez Mountains, Santa Barbara County, California. Bulletin 186, California Division of Mines and Geology. San Francisco, 1966.
- ^ Lander, E. Bruce (1994). "Recalibration and Causes of Marine Regressive-Transgressive Cycle Recorded by Middle Eocene to Lower Miocene Nonmarine Sespe Formation, Southern California Continental Plate Margin": 79–88.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Prothero, Donald R.; Donohoo, Linda L. (2001). "Magnetic Stratigraphy of the Lower Miocene (Early Hemingfordian) Sespe-Vaqueros Formations, Orange County, California": 242–253.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Deborah R. Harden. California Geology. Prentice-Hall, Inc., Upper Saddle River, NJ. 1997. ISBN 0-02-350042-5
- ^ Minor, S.A., Kellogg, K.S., Stanley, R.G., Gurrola, L.D., Keller, E.A., and Brandt, T.R., 2009, Geologic Map of the Santa Barbara Coastal Plain Area, Santa Barbara County, California: U.S. Geological Survey Scientific Investigations Map 3001, scale 1:25,000, 1 sheet, pamphlet, 38 p.