Sespe Formation
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. 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.
| 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) |
| 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) |
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