The Chatsworth Formation is a

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in the

Simi Hills The Simi Hills are a low rocky mountain range of the Transverse Ranges in eastern Ventura County and western Los Angeles County, of southern California, United States. Geography The Simi Hills are aligned east-west and run for , and average arou ...

and western

Santa Susana Mountains The Santa Susana Mountains are a transverse range of mountains in Southern California, north of the city of Los Angeles, in the United States. The range runs east-west, separating the San Fernando and Simi valleys on its south from the Santa Cla ...

of southern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

.AAPG Archives: Paleographic Interpretation of the Chatsworth Formation
/ref> It is found in western

Los Angeles County Los Angeles County, officially the County of Los Angeles, and sometimes abbreviated as L.A. County, is the most populous county in the United States and in the U.S. state of California, with 9,861,224 residents estimated as of 2022. It is the ...

and eastern

Ventura County Ventura County () is a county in the southern part of the U.S. state of California. As of the 2020 census, the population was 843,843. The largest city is Oxnard, and the county seat is the city of Ventura. Ventura County comprises the Oxnar ...

. The formation's thickness can be more than .USGS.gov: "Preliminary geologic map of the Santa Susana quadrangle, Southern California"
/ref>

Fossils

The

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

marine formation preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

dating from the Middle

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

to Early Maestrichtian epochs of the Cretaceous period. It has diverse

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

an faunas. The most common taxa are:Overview of late cretaceous marine gastropods from the Simi Hills
by Mary Stecheson, Department of Geological Sciences, California State Univ, Northridge. *ringiculid Biplica *naticids Gyrodes and Euspira *trocid Atira *aporrhaids

Anchuras Anchuras (also known as Rincón de Anchuras) is a municipality in Ciudad Real Province, Castile-La Mancha, Spain. It has a population of 342. According to the 2014 census, Anchuras municipality has a population of 202 inhabitants. The municipali ...

and Lispodesthes *turritellid

Turritella ''Turritella'' is a genus of medium-sized sea snails with an operculum, marine gastropod mollusks in the family Turritellidae.Vos, C.; Gofas, S. (2013). Turritella Lamarck, 1799. Accessed through: World Register of Marine Species at http://www.m ...

*perissityid Perissitys

References

Cretaceous California Sandstone formations of the United States Campanian Stage Maastrichtian Stage of North America Geology of Los Angeles County, California Geology of Ventura County, California Simi Hills Santa Susana Mountains Cretaceous fossil record Upper Cretaceous Series of North America Paleontology in California Chatsworth, Los Angeles Geography of Simi Valley, California West Hills, Los Angeles Geologic formations of California {{Cretaceous-stub

Fossils

See also

References