# Ione Formation

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Ione_Formation
> Markdown URL: https://mediated.wiki/source/Ione_Formation.md
> Source: https://en.wikipedia.org/wiki/Ione_Formation
> Source revision: 1337279069
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Eocene Epoch geologic formation in California}}
{{Infobox rockunit
| name           = Ione Formation
| image          = Hematitic kaolinite (Ione Formation, Middle Eocene; clay pit in the western foothills of the Sierra Nevada Mountains, central California, USA).jpg
| caption        = A rock from the Ione Formation
| type           = [Geologic formation](/source/Geologic_formation)
| age            = [Eocene](/source/Eocene)
| period         = Eocene
| prilithology   =
| otherlithology =
| namedfor       =
| namedby        =
| region         = [California](/source/California)
| country        = [United States](/source/United_States)
| coordinates    =
| unitof         =
| subunits       =
| underlies      = [Chico Formation](/source/Chico_Formation) (regionally)
| overlies       = [Martinez Formation](/source/Martinez_Formation) (regionally)
| thickness      =
| extent         =
| area           =
| map            =
| map_caption    =
}}

The '''Ione Formation''' is an [Eocene Epoch](/source/Eocene) [geologic formation](/source/Formation_(geology)) in [California](/source/California).<ref>{{Cite web |title=Science |url=https://www.science.org/action/cookieAbsent |access-date=2026-02-07 |website=AAAS |language=en |doi=10.1126/science.40.1019.67}}</ref><ref>{{Cite web |title=Type Region of the Ione Formation (Eocene), Central California: Stratigraphy, Paleogeography, and Relation to Auriferous Gravels |url=https://pubs.usgs.gov/of/2006/1378/ |access-date=2026-02-07 |website=pubs.usgs.gov}}</ref><ref>{{Cite web |title=Geolex — Ione publications |url=https://ngmdb.usgs.gov/Geolex/UnitRefs/IoneRefs_5647.html |access-date=2026-02-07 |website=ngmdb.usgs.gov}}</ref>

==Geology==
The formation regionally overlies the [Martinez Formation](/source/Martinez_Formation) and regionally underlies the [Chico Formation](/source/Chico_Formation).

=== History ===
The [auriferous](/source/auriferous) gravels accumulated on slope of [Sierra Nevada](/source/Sierra_Nevada) during the Neocene Period, and at same time there was deposited in the gulf then occupying the [Great Valley](/source/Central_Valley_(California)) a sedimentary series consisting of clays and sands.

=== Description ===
It is usually overlain by a few feet of reddish [Pleistocene](/source/Pleistocene) gravel and rests on Chico formation. The strata form flat-topped hills, and consists of a succession of light-colored clays and white or yellowish-white sandstones. The largest development occurs south of American River.

==See also==
{{Portal|California|Paleontology}}
* [List of fossiliferous stratigraphic units in California](/source/List_of_fossiliferous_stratigraphic_units_in_California)
* {{C|Paleogene California}}
* [Paleontology in California](/source/Paleontology_in_California)

== References ==
{{Reflist}}

Category:Geologic formations of California
Category:Eocene Series of North America
Category:Geology of Contra Costa County, California
Category:Geology of Los Angeles County, California
Category:Geology of Orange County, California
Category:Geology of Riverside County, California
Category:Natural history of the Santa Monica Mountains

---
Adapted from the Wikipedia article [Ione Formation](https://en.wikipedia.org/wiki/Ione_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Ione_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.