Modelo Formation
| Modelo Formation | |
|---|---|
| Stratigraphic range: Late Miocene, | |
| Type | Formation |
| Unit of | Los Angeles Basin |
| Underlies | Pico Formation |
| Overlies | Rincon Shale |
| Thickness | 600 metres (2,000 ft) |
| Lithology | |
| Primary | Shale |
| Location | |
| Region | Los Angeles County and Ventura County, California |
| Country | United States |
| Extent | Simi Hills, Santa Susana Mountains |
The Modelo Formation is a Miocene geologic formation in the Simi Hills and western Santa Susana Mountains of southern California, including under parts of Los Angeles.
It preserves fossils dating back to the Late Miocene of the Neogene period, among them a high number of fossil representatives of modern pelagic and deep-sea fish taxa (as well as some with benthic affinities), in addition to some seabirds and cetaceans. As suggested from this fauna, the sediments of the formation were likely deposited in a deepwater marine habitat at middle to upper bathyal depths within an abyssal fan, with geological changes along the San Andreas fault causing a rapid uplift during the latest Miocene, bringing these former deepwater sediments to the surface. It is likely partially contemporaneous with the Monterey Formation in some areas, such as the Ventura Basin.
Volcanic ash beds are known from the formation; these, along with fossil microorganisms, indicate that the formation was deposited between 13 and 5.5 million years ago.