{{Short description|Geologic formation in California, United States}} {{Infobox rockunit | name = Santa Susana Formation | image = | caption = | type = Formation | age = Late Paleocene-Early Eocene | period = Eocene | prilithology = Shale | otherlithology = Sandstone, conglomerate | namedfor = Santa Susana, California | namedby = | region = Los Angeles County and Ventura County, California | country = United States | coordinates = | unitof = | subunits = | underlies = Meganos Formation | overlies = Martinez Formation | thickness = {{convert|1000|-|1500|ft|m|abbr=on}} | extent = Simi Hills, Santa Susana Mountains | area = | map = | map_caption = }}
The '''Santa Susana Formation''' is a Paleogene period geologic formation in the Simi Hills and western Santa Susana Mountains of southern California.<ref name=usgs>[https://ngmdb.usgs.gov/Geolex/UnitRefs/SantaSusanaRefs_11777.html USGS.gov: Geolex - Santa Susana Formation]; accessed 8.15.2015</ref><ref name=panpacific>[https://ngmdb.usgs.gov/Prodesc/proddesc_88561.htm "A summary of work in progress on the Tertiary and Quaternary of western North America"]; Clark, B.L.; Pan-Pacific [2nd] Science Congress Proceedings, Australia, v. 1, p. 874-879 (1924); accessed 8.15.2015.</ref><ref name=martinez>[https://ngmdb.usgs.gov/Prodesc/proddesc_92186.htm "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); [p. 397-466]; accessed 8.15.2015.</ref>
The formation consists largely of light-gray shale and some fine-grained shaly sandstone, with a lens of heavy conglomerates in the lower part.<ref name=usgs/><ref name=usgsmap>[https://pubs.usgs.gov/of/1995/0829/report.pdf USGS.gov: "Preliminary geologic map of the Santa Susana quadrangle, Southern California"]; R. F. Yerkes1 and R. H. Campbell; accessed 8.15.2015.</ref> Small beds of limestone are also present.<ref>Campbell, R.H., Wills, C.J., Irvine, P.J., and Swanson, B.J., 2016. Preliminary geologic map of the Los Angeles 30' x 60' quadrangle, California.Version 2.1, California Geological Survey, Preliminary Geologic Maps PGM-13-06 https://ngmdb.usgs.gov/mapview/?center=-118.371,34.313&zoom=10</ref> It is from {{convert|1000|to|1500|ft|m}} thick.<ref name=usgs/><ref name=usgsmap/>
== Fossil content == The Santa Susana Formation preserves fossils from the Late Paleocene to Early Eocene epochs in the Paleogene period of the Cenozoic Era.<ref name=usgsmap/><ref>{{cite web|title= Fossilworks: Gateway to the Paleobiology Database|author= ((Various Contributors to the Paleobiology Database))|url= https://www.fossilworks.org/|access-date= 17 December 2021|archive-date= 25 March 2022|archive-url= https://web.archive.org/web/20220325060448/http://www.fossilworks.org/cgi-bin/bridge.pl?action=home|url-status= dead}}</ref> Fossilized fauna in the Santa Susana Formation is entirely different from that of underlying Martinez Formation, and has very little in common with that of the overlying Meganos Formation.<ref name=usgs/><ref name=martinez/><ref>[https://ngmdb.usgs.gov/Prodesc/proddesc_89767.htm "Checklist of California Tertiary marine Mollusca"]; Keen, A.M., and Bentson, Herdis; Geological Society of America Special Paper, 56, 280 p. (1944); [Pg. 21 (fig. 4) shows age as [late] Paleocene through early Eocene]; accessed 8.15.2015.</ref>
== See also == {{Portal|Earth sciences|California|Paleontology}} * {{C|Geology of Los Angeles County, California}} * List of fossiliferous stratigraphic units in California * {{C|Paleogene California}} * Paleontology in California
== References == {{Reflist|2}}
== External links == *{{commons category-inline|Santa Susana Formation (California)}}
Category:Geologic formations of California Category:Paleocene Series of North America Category:Eocene Series of North America Category:Paleogene California Category:Conglomerate formations of the United States Category:Sandstone formations of the United States Category:Shale formations of the United States Category:Geology of Los Angeles County, California Category:Geology of Ventura County, California Category:Simi Hills Category:Santa Susana Mountains Category:Chatsworth, Los Angeles Category:Simi Valley, California Category:West Hills, Los Angeles Category:Paleontology in California