The Santa Susana Formation is a

Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of ...

period

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 ar ...

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 ...

of southern

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

.USGS.gov: Geolex - Santa Susana Formation
accessed 8.15.2015
Clark, B.L.; Pan-Pacific ndScience Congress Proceedings, Australia, v. 1, p. 874-879 (1924); accessed 8.15.2015."A contribution to the paleontology of the Martinez Eocene of California"
Nelson, R. N.; University of California Publications in Geological Sciences v. 15, no. 11 (1925); . 397-466 accessed 8.15.2015. The formation consists largely of light-gray

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

and some fine-grained shaly

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 ...

, with a lens of heavy

conglomerate Conglomerate or conglomeration may refer to: * Conglomerate (company) * Conglomerate (geology) * Conglomerate (mathematics) In popular culture: * The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes ** C ...

s in the lower part. USGS.gov: "Preliminary geologic map of the Santa Susana quadrangle, Southern California"
R. F. Yerkes1 and R. H. Campbell; accessed 8.15.2015. Small beds of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

are also present. It is from thick.

Fossil content

The Santa Susana 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 ...

from the

Late Paleocene The Thanetian is, in the ICS Geologic timescale, the latest age or uppermost stratigraphic stage of the Paleocene Epoch or Series. It spans the time between . The Thanetian is preceded by the Selandian Age and followed by the Ypresian Age (part ...

Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

s in the Paleogene

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 ...

of the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

Era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. Com ...

. Fossilized fauna in the Santa Susana Formation is entirely different from that of underlying

Martinez Formation The Martinez Formation is an Eocene Epoch geologic formation in California. Geology The formation regionally overlies the Chico Formation and regionally underlies the Tejon Formation or the Ione Formation. It is exposed in the Clevelin Hill ...

, and has very little in common with that of the overlying Meganos Formation."Checklist of California Tertiary marine Mollusca"
Keen, A.M., and Bentson, Herdis; Geological Society of America Special Paper, 56, 280 p. (1944); g. 21 (fig. 4) shows age as [latePaleocene through early Eocene">ate.html" ;"title="g. 21 (fig. 4) shows age as [late">g. 21 (fig. 4) shows age as [latePaleocene through early Eocene accessed 8.15.2015.

References

External links

*{{commons category-inline, Santa Susana Formation (California) Geologic formations of California Paleocene Series of North America Eocene Series of North America Paleogene California Conglomerate formations Sandstone formations of the United States Shale formations of the United States Geology of Los Angeles County, California Geology of Ventura County, California Simi Hills Santa Susana Mountains Chatsworth, Los Angeles Geography of Simi Valley, California West Hills, Los Angeles Paleontology in California

Fossil content

See also

References

External links