Moraga Formation

{{Short description|Pliocene geological formation in California}}

{{Infobox rockunit

| name = Moraga Formation
(Moraga Volcanics)

| image =Sibley Volcanic Regional Preserve - Stierch A.jpg

| caption = Moraga Volcanics in Robert Sibley Volcanic Regional Preserve, Berkeley Hills

| type = Geologic formation

| age = Pliocene epoch

| period = Pliocene

| prilithology = Basaltic lava, with
andesite, basalt, rhyolite tuff

| otherlithology =Clay, conglomerate, limestone

| namedfor = Moraga Valley

| namedby =

| region = Berkeley Hills,
Alameda County and
Contra Costa County,
California

| country = United States

| coordinates =

| unitof =

| subunits =

| underlies = Siesta Formation

| overlies = Orinda Formation

| thickness = {{convert|1200 |ft|m}}

| extent =

| area =

| map =

| map_caption =

}}

The Moraga Formation, also known as the Moraga Volcanics, is a geological formation that dates back to the Pliocene epoch. It is located in Berkeley Hills, East Bay Region, San Francisco Bay Area, California.[https://pubs.usgs.gov/bul/1251j/report.pdf USGS.gov: "Upper Cretaceous and Lower Tertiary Rocks Berkeley and San Leandro Hills, California"], by J. E. Case, GEOLOGICAL SURVEY BULLETIN 1251-J, 1968.

The basaltic lava flow formation is found within Alameda County and Contra Costa County.[https://oaklandgeology.wordpress.com/2011/07/25/grizzly-peak-and-moraga-basalt/ Oakland Geology Blog: "Grizzly Peak and Moraga basalt"] It can be seen in the Robert Sibley Volcanic Regional Preserve and Caldecott Tunnel area of the Berkeley Hills.[http://geology.about.com/od/geophoto_tours/ig/CAtransecttrip/stop30overview.htm Geology.about.com: "California Transect - Stop 30, Orinda Formation and Moraga Volcanics"] It is named for an exposed occurrence in the Moraga Valley.

It overlies the Orinda Formation, and underlies the Siesta Formation.[http://newscenter.lbl.gov/2010/07/06/geologist-studies-ground/ Lawrence Berkeley Lab.gov: "Berkeley Lab Geologist Studies the Ground Beneath His Feet"]

It preserves freshwater fossils dating back to the Pliocene epoch of the Neogene period.{{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}}