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Sespe Formation
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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]
Quick Facts Type, Underlies ...
Sespe Formation | |
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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 | ![]() |
Type section | |
Named for | Sespe Creek |
Named by | Watts (1897); redefined by Kew (1924)[2] |
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