View source for Anza-Borrego Desert State Park

{{Short description|State park in California, United States}}
{{Use dmy dates|date=August 2022}}
{{Infobox protected area
| name = Anza-Borrego Desert State Park
| iucn_category = III
| photo = Fontspoint02262006.JPG
| photo_caption = Desert view from Font's Point
| photo_alt = View of the park's desert landscape from Font's Point
| map = USA California#USA
| relief = 1
| location = [[San Diego County, California|San Diego]], [[Imperial County, California|Imperial]], and [[Riverside County, California|Riverside]] counties, [[California]], US
| nearest_city = [[Borrego Springs, California|Borrego Springs]] and [[Julian, California|Julian]], California
| coordinates = {{Coord|33|15|33|N|116|23|57|W|region:US-CA|display=inline, title}}
| area_acre = 650000
| established = 1932<ref>[https://sandiegohistory.org/journal/1973/october/anza/ History in the California Desert] ''The Journal of San Diego History'', San Diego Historical Society Quarterly, Fall 1973, Volume 19, Number 4, San Diego History Center, sandiegohistory.org</ref>
| visitation_num =
| visitation_year =
| governing_body = [[California Department of Parks and Recreation]]
| embedded = {{Infobox designation list | embed = yes
  | designation1 = NNL
  | designation1_date = 1974
  }}
}}

'''Anza-Borrego Desert State Park''' ({{IPAc-en|'|æ|n|z|ə|_|b|ə|'|r|eɪ|g|oʊ}}, ''[[Help:Pronunciation respelling key|AN-zə bə-RAY-goh]]'') is a [[California State Park]] located within the [[Colorado Desert]] of [[Southern California]], United States. Created in 1932, the park takes its name from 18th century Spanish explorer [[Juan Bautista de Anza]] and ''borrego'', a Spanish word for sheep.<ref name="BrightGudde1998">{{cite book |author1=William Bright |author2=Erwin Gustav Gudde |title=1500 California place names: their origin and meaning |url=https://books.google.com/books?id=CET4QodMZysC |access-date=20 January 2012 |date=1998 |publisher=University of California Press |isbn=978-0-520-21271-8 |page=16 |archive-date=28 June 2011 |archive-url=https://web.archive.org/web/20110628232939/http://books.google.com/books?id=CET4QodMZysC |url-status=live }}</ref> With {{cvt|650,000|acres|ha}} that includes one-fifth of [[San Diego County, California|San Diego County]], it is the largest state park in California and the third largest state park nationally.
<ref>{{cite web |url=https://theabf.org/experience-anza-borrego/ |title=Anza-Borrego Desert State Park |website=Anza-Borrego Foundation |access-date=8 September 2025 }}</ref><ref name="Negrete">Negrete, Ninfa; Ramirez, Sara; Wong, Robert (Fall 2018). "Human-wildlife interactions in Anza-Borrego Desert State Park". ''California Ecology and Conservation Research'': 9 – via Google Scholar</ref>

The park occupies eastern San Diego County and reaches into [[Imperial County, California|Imperial]] and [[Riverside County, California|Riverside]] counties, enveloping two communities: [[Borrego Springs, California|Borrego Springs]], which is home to the park's headquarters, and [[Shelter Valley, California|Shelter Valley]].

==Geography==
[[File:Portrait of Juan Bautista de Anza (Painted by Fray Orci; 1774, Mexico City).jpg|thumb|left|upright|[[Juan Bautista de Anza]], Spanish expeditionary and namesake of the park]]

The park is an anchor in the [[Mojave and Colorado Deserts Biosphere Reserve]], and adjacent to the [[Santa Rosa and San Jacinto Mountains National Monument]].

The great bowl of the surrounding desert is surrounded by mountains, with the [[Vallecito Mountains]] to the south and the highest [[Santa Rosa Mountains (California)|Santa Rosa Mountains]] to the north which are in the wilderness area, without paved roads and with the only year-round [[Stream|creeks]].[[File:Blair Valley.jpg|thumb|Blair Valley]]

'''Blair Valley''' is a valley in the State Park.<ref>{{cite web |url=https://www.peakbagger.com/map/BigMap.aspx?cy=32.701888&cx=-116.763918&z=13&l=L_CT%7CL_MT%7CL_AG%7CL_OS&hj=0&t=P&d=21331&c=0&a=0&sx=-999&sy=-999&cyn=0 |title=Peakbagger.com Large Map Page |access-date=3 January 2020 |archive-date=14 October 2018 |archive-url=https://web.archive.org/web/20181014164906/http://www.peakbagger.com/map/BigMap.aspx?cy=32.701888&cx=-116.763918&z=13&l=L_CT%7CL_MT%7CL_AG%7CL_OS&hj=0&t=P&d=21331&c=0&a=0&sx=-999&sy=-999&cyn=0 |url-status=live }}</ref>
It consists of the main Blair Valley and '''Little Blair Valley''' separated by a small mountain range over which ''Foot and Walker Pass'' leads.
To the west of the valley lies [[Granite Mountain (California)|Granite Mountain]], to the east the range of [[Vallecito Mountains]].

The valley can be crossed by dirt roads, e.g., to reach a look-out point over ''Smuggler Canyon'' or sites of Indian pre-Hispanic art.{{Citation needed|date=July 2022}}

'''Borrego Palm Canyon''' is the site of park headquarters and has "the most famous view point in the park, overlooking barren, spectacularly eroded Borrego Badlands." '''Tamarisk Grove''' hosts a campground and is close to [[Yaqui Well]], a "historic watering spot...with magnificent [[Olneya|desert ironwood]] trees and a busy wildlife population."<ref name="sunset">{{cite book |date=1974 |title=Sunset Travel Guide to Southern California |location=Menlo Park, Calif. |publisher=Lane Publishing Co. |pages=110–111 |sbn=376-06754-3}}</ref>

==Visiting==
[[File:Vista of Anza Borrego.jpg|thumb|Vista of the Anza-Borrego desert landscape]]

{{blockquote|title=''Sunset Travel Guide to Southern California'' (1974)|Anza-Borrego is often pictured as a wrinkled wasteland of harshly eroded, nearly barren clay and gravel, possibly because its gullied badlands are its most eroded phenomenon. There is more to it than that: cool piney heights, springs and oozing [[ciénega]]s, spectacular although brief waves of wild flowers in spring, and native fragrances of pervasive sage, subtle cottonwood, and even more subtle earth.}}
The park has {{convert|500|mi|km|abbr=on}} of dirt roads, 12 designated [[wilderness area]]s, and {{convert|110|mi|km|abbr=on}} of [[Trail|hiking trails]]. Park information and maps are available in the visitor center.<ref name="www.parks.ca.gov">{{cite web |url=http://www.parks.ca.gov/?page_id=1016 |title=Visiting the Park |website=www.parks.ca.gov |access-date=22 June 2010 |archive-date=22 June 2010 |archive-url=https://web.archive.org/web/20100622081337/http://www.parks.ca.gov/?page_id=1016 |url-status=live }}</ref> The park has [[Wi-Fi]] access.{{Citation needed|date=October 2019}}

The park is approximately a two-hour drive northeast from [[San Diego, California|San Diego]], southeast from [[Riverside, California|Riverside]] or [[Irvine, California|Irvine]], and south from [[Palm Springs, California|Palm Springs]]. Access on the east-[[Coachella Valley]] side is via [[County Route S22 (California)|County Route S22]] and [[State Route 78 (California)|State Route 78]]. Access on the west-[[Pacific Ocean]] side is via California County Route S2 and State Route 78. SR-79 provides access through the high and forested [[Laguna Mountains]], such as in [[Cuyamaca Rancho State Park]].<ref>{{cite web |url=http://www.parks.ca.gov/lat_long_map/default.asp?lvl_id%3D278 |title=Park Location and Directions |website=parks.ca.gov |publisher=California State Parks |url-status=dead |archive-url=https://web.archive.org/web/20100626012635/http://www.parks.ca.gov//lat_long_map/default.asp?lvl_id=278 |archive-date=26 June 2010 |access-date=22 June 2010}}</ref> These highways climb from the coast to {{convert|2400|ft|m|abbr=on}} above sea level, then descend {{convert|2000|ft|m|abbr=on}} down into the [[Borrego Springs, California|Borrego Valley]] in the center of the park.  Access from the south is via the southern portion of S2.
[[File:Ocotillo Sunrise.jpg|alt=A large ocotillo silhouetted against a blazing sunrise in Anza-Borrego Desert State Park. |thumb|A large ocotillo silhouetted against a blazing sunrise in Anza-Borrego Desert State Park. ]]
A popular site to hike to near the visitor center is Hellhole Palms, a grove of [[Washingtonia filifera|California fan palms]] in Hellhole Canyon near Maidenhair Falls. The park also provides access points to the [[Pacific Crest Trail]] and the [[Juan Bautista de Anza National Historic Trail]].<ref name="www.parks.ca.gov"/><ref>{{Cite web |title=Anza-Borrecio Desert State Park |url=https://www.parks.ca.gov/pages/638/files/abdsp_Park_Map201704.pdf |website=www.parks.ca.gov}}</ref>

Stargazing is another activity at Anza-Borrego. The park was designated an [[Dark-sky preserve|International Dark Sky Park]] by the [[International Dark-Sky Association]] in 2018.<ref>{{Cite web |date=19 January 2018 |title=Anza-Borrego Desert State Park Recognized as an International Dark Sky Park |url=https://www.darksky.org/anza-borrego-desert-state-park-recognized-as-an-international-dark-sky-park/ |access-date=13 November 2021 |website=International Dark-Sky Association |language=en-US |archive-date=12 November 2021 |archive-url=https://web.archive.org/web/20211112222550/https://www.darksky.org/anza-borrego-desert-state-park-recognized-as-an-international-dark-sky-park/ |url-status=live }}</ref>

Ecotourism is big for Anza-Borrego. On average, the population of Borrego Springs increases by about 580% in peak wildflower [[superbloom]] season. This is a shift from around 3400 long-term residents to around 200,000 tourists.<ref>{{Cite journal |last1=Winkler |first1=Daniel E. |last2=Brooks |first2=Emily |date=2020-04-01 |title=Tracing Extremes across Iconic Desert Landscapes: Socio-Ecological and Cultural Responses to Climate Change, Water Scarcity, and Wildflower Superblooms |url=https://doi.org/10.1007/s10745-020-00145-5 |journal=Human Ecology |language=en |volume=48 |issue=2 |pages=211–223 |doi=10.1007/s10745-020-00145-5 |bibcode=2020HumEc..48..211W |issn=1572-9915|url-access=subscription }}</ref>

==Flora and fauna==
{{See also|Category:Flora of the California desert regions|Category:Fauna of the Colorado Desert}}
[[File:Cactus bloom.jpg|thumb|170px|left|Cactus in bloom]]
[[File:Bighorns.jpg|thumb|right|150px|[[Desert bighorn sheep]] at Palm Canyon [[Oasis]].]]
The [[habitat]]s are primarily within the [[Colorado Desert]] [[ecosystem]] of the [[Sonoran Desert]] [[ecoregion]]. The higher extreme northern and eastern sections in the [[Peninsular Ranges]] are in the [[California montane chaparral and woodlands]] ecoregion. The park has about 600 species of native plants.<ref name="sunset" />

The park contains [[alluvial fan|''bajadas'']] and desert washes; rock formations and colorful [[badlands]], large arid landscapes, and mountains.

The bajadas are predominantly creosote bush-bur sage with creosote bush (''[[Larrea tridentata]]'') and the palo verde-cactus shrub ecosystems with the palo verde tree (''[[Parkinsonia microphylla]]''), [[Cactus|cacti]], and [[Fouquieria splendens|ocotillo]]. In the washes, Colorado/Sonoran microphylla woodlands can be found. These woodlands include such plants as smoke tree (''[[Psorothamnus spinosus]]''), velvet mesquite (''[[Prosopis velutina]]''), and catclaw (''[[Senegalia greggii|Acacia greggii]]'').<ref>{{cite web |url=http://www.parks.ca.gov/mediagallery/?page_id=638 |title= Gallery {{!}} State Park: Anza-Borrego Desert |website=parks.ca.gov |publisher=California State Parks |access-date=22 June 2010 |archive-date=26 June 2010 |archive-url=https://web.archive.org/web/20100626003838/http://www.parks.ca.gov/mediagallery/?page_id=638 |url-status=dead}}</ref> The park is home to elephant trees (''[[Bursera microphylla]]''), which are "fairly common in parts of Baja California but north of the border practically confined to the Anza-Borrego region."<ref name="sunset" />

The park has natural [[Spring (hydrology)|springs]] and [[Oasis|oases]], with the state's only native palm, the [[Washingtonia filifera|California fan palm]]. Seasonal wildflower displays can be seen in many plant community association throughout the park.<ref>{{Cite news |url=https://www.kpbs.org/news/2019/mar/06/how-enjoy-anza-borrego-super-bloom/ |title=How To Enjoy The Anza-Borrego Desert Super Bloom |last1=Monet |first1=Ebone |last2=Colbert |first2=Anica |date=6 March 2019 |work=KPBS Public Media |language=en |access-date=7 March 2019 |archive-date=8 March 2019 |archive-url=https://web.archive.org/web/20190308002925/https://www.kpbs.org/news/2019/mar/06/how-enjoy-anza-borrego-super-bloom/ |url-status=live }}</ref> [[Superbloom]]s, one of the biggest Anza-Borrego State Park attractions, are indispensable indicators of the increasingly severe implications of climate change, precipitation levels, and shifting seasonal starting and ending periods.{{r|Barbour 2019}} Superblooms are fundamental healthy and natural aspects to this desert, as it boosts the local economy with the influx of tourism and is vital player in the desert biome.<ref name="BrightGudde1998" />

The high-country to the north and east has [[closed-cone pine forest]]s, [[manzanita]]s and [[California oak woodland|oak woodlands]].{{Citation needed|date=October 2023}}

The oases are prolific with many types of fauna, especially for bird-watching. Throughout the park, visitors may see [[bighorn sheep]], [[Cougar|mountain lions]], [[badger]]s, [[kit fox]]es, [[mule deer]], [[coyote]]s, [[greater roadrunner]]s, [[golden eagle]]s, [[black-tailed jackrabbit]]s, [[ground squirrel]]s, [[kangaroo rat]]s, deer mouse, [[quail]], and [[prairie falcon]]s. In the reptile class, [[desert iguana]]s, [[chuckwalla]]s, and the [[Crotalus ruber|red diamond rattlesnakes]] can be seen.<ref>DesertUSA.com</ref><ref name="Negrete" />

Anza-Borrego Desert State Park is home to multiple [[endangered species]]. Unfortunately, the building of roads and highways have a severe effect upon these species and roadkills are cause for serious concern. Roads not only contribute to habitat fragmentation which starkly divides ecosystems, but led to 18 roadkillings within just 5 days in a recent study done in 2018.<ref name="Negrete" />

===Bighorn sheep===
Some areas are habitats for the [[desert bighorn sheep]]. The peninsula bighorn sheep reside in Anza-Borrego. They have been federally endangered since 1998 and are one of the most iconic species of this state park.<ref name="Negrete" /> Observers count this [[endangered species]] to study the population, and monitor its current decline from [[Habitat fragmentation|human encroachment]].<ref>C. Michael Hogan. 2009. California Fan Palm: ''Washingtonia filifera'', GlobalTwitcher.com, ed. Nicklas Stromberg</ref> The two biggest threats to bighorn sheep populations are anthropogenic influences and climate change. As humans continue to develop in Anza-Borrego Desert State Park and the surrounding area, bighorn sheep continue to lose their habitat. Coupled with the increasing extreme temperatures and decrease in precipitation, bighorn shape face a decreasing free-standing water availability crisis. Bighorn sheep face considerable habitat loss at the hands of humans ranging from water diversion to noise pollution and habitat fragmentation. As critical members of this desert biome, it is important to recognize the necessity to protect them and mitigate our impact on their limited and unique environment.<ref>{{Cite journal |last=Dolan |first=Brian F. |date=2006 |title=Water Developments and Desert Bighorn Sheep: Implications for Conservation |url=https://www.jstor.org/stable/3784691 |journal=Wildlife Society Bulletin |volume=34 |issue=3 |pages=642–646 |doi=10.2193/0091-7648(2006)34[642:WDADBS]2.0.CO;2 |jstor=3784691 |issn=0091-7648|url-access=subscription }}</ref>

==Climate and its impact on the landscape==
Anza-Borrego State Park is located in the Colorado Desert Region of Southern California which is an extension of the Mexican Sonoran Desert. The [[Köppen climate classification|Koppen Climate]] classification for Anza Borrego Desert State Park is [[BWh]]. The characteristics of this climate are typically hot and arid along with a deficiency in precipitation due to the continental tropical air mass which has very dry warm air.<ref>{{Cite journal |last=Barbour |first=M |date=31 December 2019 |title=Colorado Desert Vegetation |url=https://www.degruyter.com/document/doi/10.1525/9780520933361-025/html |journal=Terrestrial Vegetation of California |pages=657–682 |doi=10.1525/9780520933361-025 |isbn=978-0-520-93336-1 |url-access=subscription }}</ref> As climate change increases there is potential for wetter years which bring about "super blooms," that boost tourism during the winter and early spring. Locals began to rely on seasonal tourism to boost their economies, and, along with wet years climate change has threatened the economy as it has the ability to produce longer droughts which threaten the tourist dependent towns nearby.<ref>{{Cite journal |last=Winkler |first=Daniel |date=April 2020 |title=Tracing extremes across iconic desert landscapes: Socio-ecological and cultural responses to climate change, water scarcity, and wildflower Superblooms |url=https://www.jstor.org/stable/45295518 |journal=Human Ecology |volume=48 |issue=2 |pages=215–219 |doi=10.1007/s10745-020-00145-5 |jstor=45295518 |bibcode=2020HumEc..48..211W }}</ref> As the environment changes with climate desertification, locals and developers search for ways to maintain tourism, some attempt to maintain steady tourism with mega development of resorts or artificial oases. However, a study conducted on North-West China deserts in 2020 showed that artificial oases vegetation is not acclimated to drought conditions, and they consume large amounts of groundwater which deplete the water table level and outcompete native vegetation that store water in their roots.<ref>{{Cite journal |last=Luo |first=Lihui |date=Aug 2020 |title=The Hidden Costs of Desert Development |url=https://www.proquest.com/docview/2405360412 |journal=The Royal Swedish Academy of Sciences |volume=49 |issue=8 |pages=1413, 1415, 1419 |doi=10.1007/s13280-019-01287-7 |pmid=31749101 |pmc=7239957 |bibcode=2020Ambio..49.1412L |id={{ProQuest|2405360412}} }}</ref> Since deserts have such extreme weather, the species that inhabit them are highly dependent on each other, and developing on deserts or creating artificial oases will not only impact vegetation but also animals.

{{Weather box|Jan record high F=90|Jan high F=69.3|Jan low F=44.0|Jan record low F=20|Jan precipitation inch=1.11|Jan snow inch=0|Feb record high F=95|Feb high F=72.3|Feb low F=46.5|Feb record low F=24|Feb precipitation inch=1.08|Mar record high F=101|Mar high F=77.9|Mar low F=50.0|Mar record low F=28|Mar precipitation inch=0.70|Mar snow inch=0|Apr record high F=111|Apr high F=84.5|Apr low F=53.8|Apr record low F=28|Apr precipitation inch=0.23|Apr snow inch=0|May record high F=114|May high F=93.2|May low F=60.7|May record low F=34|May precipitation inch=0.06|May snow inch=0|Jun record high F=122|Jun high F=102.7|Jun low F=68.4|Jun record low F=45|Jun precipitation inch=0.02|Jun snow inch=0|Jul record high F=121|Jul high F=107.4|Jul low F=75.8|Jul record low F=56|Jul precipitation inch=0.28|Jul snow inch=0|Aug record high F=120|Aug high F=106.1|Aug low F=75.5|Aug record low F=55|Aug precipitation inch=0.51|Aug snow inch=0|Sep record high F=117|Sep high F=101.0|Sep low F=70.3|Sep record low F=49|Sep precipitation inch=0.30|Sep snow inch=0|Oct record high F=113|Oct high F=89.7|Oct low F=60.6|Oct record low F=33|Oct precipitation inch=0.30|Oct snow inch=0|Nov record high F=98|Nov high F=77.9|Nov low F=50.4|Nov record low F=31|Nov precipitation inch=0.45|Nov snow inch=0|Dec record high F=87|Dec high F=68.9|Dec low F=43.4|Dec record low F=23|Dec precipitation inch=0.80|Dec snow inch=0.1|single line=Y|source 1=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0983|location=Borrego Desert Park, CA|precipitation colour=green|Feb snow inch=0}}

==Geology and paleontology==
[[File:Pano-fonts-point.jpg|thumb|right|550px|Panoramic view from Font's Point westward over Borrego Valley to the [[Laguna Mountains]]]]

The expanses of Anza-Borrego Desert State Park's eroded [[badlands]] also provide a different view into the region's long-vanished tropical past. The inland of southeastern California was not always a [[desert]]. [[Paleontology]], the study of the [[fossil]]ized remains of ancient life, is the key to understanding this prehistoric world. The park has an exceptional fossil record which includes preserved plants, a variety of [[invertebrate]] shells, animal tracks, and an array of bones and teeth. Most fossils found in the park date from six million to under a half million years in age (the [[Pliocene]] and [[Pleistocene]] epochs), or about 60 million years after the last [[dinosaur]] age ended.<ref>George T. Jefferson and Lowell Lindsay, 2006, ''Fossil Treasures of the Anza-Borrego Desert,'' ([[Sunbelt Publications]], San Diego) {{ISBN|0-932653-50-2}}</ref>

===Geology===
[[File:Anza borrego plants.jpg|thumb|250px|Anza-Borrego rock outcrop and flora]]
[[File:Anza Borrego Agua Caliente.jpg|thumb|250px|Agua Caliente Springs and valley towards south]]

Anza-Borrego Desert State Park lies in a unique geologic setting along the western margin of the Salton Trough. This major topographic depression with the [[Salton Sink]] having elevations of {{convert|200|ft|m|abbr=on}} below sea level, forms the northernmost end of an active [[rift valley]] and a geological [[Plate tectonics|continental plate]] boundary. The trough extends north from the Gulf of California to [[San Gorgonio Pass]], and from the eastern rim of the [[Peninsular Ranges]] eastward to the [[San Andreas Fault]] zone along the far side of the [[Coachella Valley]].

Over the past seven million years, a relatively complete geologic record of over {{convert|20000|ft|m|abbr=on}} of fossil-bearing sediment has been deposited within the park along the rift valley's western margin. Paleontological remains are widespread and diverse, and are found scattered over hundreds of square miles of eroded badlands terrain extending south from the [[Santa Rosa Mountains (California)|Santa Rosa Mountains]] into northern [[Baja California]] in Mexico.

Both marine and terrestrial environments are represented by this long and rich fossil record. Six million years ago, the ancestral [[Gulf of California]] filled the Salton Trough, extending northward past what would become the city of Palm Springs. These tropical waters supported a profusion of both large and small marine organisms. Through time, the sea gave way as an immense volume of sediment eroded during the formation of the [[Grand Canyon]] spilled into the Salton Trough. Little by little, the ancestral [[Colorado River]] built a massive [[river delta]] across the seaway. Fossil hardwoods from the deltaic sands and associated coastal plain deposits suggest the region received three times as much rainfall as now.

The Anza-Borrego region gradually changed from a predominantly marine environment into a system of interrelated terrestrial habitats. North of the [[Colorado River Delta]] and intermittently fed by the river, a sequence of lakes and [[dry lake]]s has persisted for over three million years. At the same time, sediments eroded from the growing Santa Rosa Mountains and the other Peninsular Ranges to spread east into the trough. These sediments provide an almost unbroken terrestrial fossil record, ending only a half million years ago. Here, the deposits of ancient streams and rivers trapped the remains of wildlife that inhabited a vast brushland [[savanna]]h laced with [[Riparian zone|riparian]] [[woodland]]s.

===Fossils===
This record of changing environments and habitats includes over 550 types of fossil plants and animals, ranging from the preserved microscopic plant [[pollen]] and [[Algae|algal]] [[spore]]s to [[baleen whale]] bones and mammoth skeletons. Many of the species are extinct and some are known only from fossil remains recovered from this park. Combined with a long and complete sedimentary depositional sequence, these diverse fossil assemblages are an unparalleled paleontologic resource of international importance.

Both the [[Pliocene]]-[[Pleistocene]] epoch boundary and the [[Blancan]]-[[Irvingtonian]] [[North American land mammal age]]s boundary fall within the long geological record from the Anza-Borrego region. Environmental changes associated with these geological time divisions are probably better tracked by fossils from the Anza-Borrego region than in any other [[North America]]n continental [[Platform (geology)|platform stratum]]. These changes herald the beginning of the [[Ice age|Ice Ages]], and the strata contain fossil clues to the origin and development of modern southwestern desert landscapes.

The first fossils, marine shells from the ancient Gulf of California and freshwater shells from a prehistoric era [[Lake Cahuilla]], the precursor of present-day [[Salton Sea]], were collected and described by William Blake in 1853. Blake was the [[geologist]] and [[Mineralogy|mineralogist]] for the [[Pacific Railroad Surveys]] commissioned by Congress and President [[Franklin Pierce]] to find a railway route to the Pacific. Blake first named this region the Colorado Desert.

===Marine period===
[[File:AnzaSunCaveByPhilKonstantin.jpg|thumb|[[Pre-Columbian era]] [[rock art]] in the Indian Hill archeological area]]

Since the late 19th century, numerous scientific studies and published papers have centered on the marine organisms that inhabited the ancient Gulf of California. Fossil assemblages from the classic [[Imperial Formation]] include [[calcareous]] [[Plankton|nanoplankton]] and [[dinoflagellate]]s, [[foraminifera]], [[coral]]s, [[polychaete]]s, [[clam]]s, [[Gastropoda|gastropods]], [[sea urchin]]s, [[sand dollar]]s, and crabs and shrimp. The deposits also yield the remains of [[marine vertebrate]]s, such as [[shark]]s and [[Stingray|rays]], [[Osteichthyes|bony fish]], [[baleen whale]]s, [[walrus]]es and [[dugong]]s.

Marine environments such as an outer and inner shelf, platform reef, nearshore beach, and [[lagoon]], are all represented within the Imperial Formation. As the sea became more shallow, [[Estuary|estuarine]] and [[Brackish water|brackish]] marine conditions prevailed, typified by thick channel deposits of oyster and pecten shell [[coquina]] that now form the "Elephant Knees" along Fish Creek. Many of the marine fossils are closely related to forms from the [[Caribbean Sea]]. They document a time before the [[Isthmus of Panama]] formed when the warm [[Gulf Stream]] of the western [[Atlantic Ocean]] invaded eastern [[Pacific Ocean]] waters.

===Terrestrial period===
As North and [[South America]] connected about three million years ago, terrestrial faunal north–south migrations began on a continental scale called the [[Great American Interchange]], and are present in Anza-Borrego's fossils. Animals such as giant [[ground sloth]]s and [[porcupine]]s made their first appearance in North America at this time.

The oldest terrestrial vertebrate fossils from the [[Colorado Desert]] predate the late [[Miocene]] invasion of the Gulf of California. These very rare fossils include a [[gomphothere]] (elephant-like mammal), [[rodent]], [[Felidae|felid]] and small [[camelid]], and were collected from 10– to 12-million-year-old [[river]]ine and near-shore lake deposits. However, the most significant and abundant vertebrate fossils have been recovered from the latest [[Miocene]] through late-[[Pleistocene]] riverine and flood plain deposits of the [[Palm Spring Formation]] in the Vallecito and Fish Creek Badlands and [[Ocotillo Conglomerate]] exposed in the Borrego Badlands. These fossil assemblages occur in a 3.5-million-year-long, uninterrupted stratigraphic sequence that has been dated using horizons of volcanic ash and [[Paleomagnetism|paleomagnetic]] methods.

The [[bestiary]] for this savannah landscape includes some of the most unusual creatures to inhabit North America – animals such as:<br />''[[Geochelone]]'', a giant bathtub-sized tortoise; ''[[Aiolornis|Aiolornis incredibilis]]'', the largest flying bird of the Northern Hemisphere, with 17-ft (5.2-m) wing span; ''[[Paramylodon]]'', ''[[Megalonyx]]'' and ''[[Nothrotheriops]]'', giant ground sloths, some with bony armor within their skin; ''[[Pewelagus]]'', a very small rabbit; ''[[Borophagus]]'', a [[hyena]]-like dog; ''[[Arctodus]]'', a giant [[Arctodus|short-faced bear]]; ''[[Smilodon]]'', a [[saber-toothed cat]]; ''[[Miracinonyx]]'', the North American cheetah; ''[[Mammuthus imperator]]'', the largest known [[mammoth]]; ''Tapirus'', an extinct [[tapir]]; ''[[Equus enormis]]'' and ''[[Equus scotti]]'', two species of extinct Pleistocene horses; ''[[Gigantocamelus]]'' a giant camel; and ''[[Capromeryx minor]]'', the dwarf [[pronghorn]]. Within the state park, Mammuthus remains, including two complete skulls and a partial skeleton, have been uncovered at 46 different archeological sites. Most of these sites are located in the Borrego Badlands. ''[[Gomphotherium|Gompotherium]], [[Stegomastodon]],'' ''[[Mammuthus meridionalis]],'' and ''Mammuthus columbi'' are among the various mammoth fossils to be found in Anza-Borrego Desert State Park. A ''[[Gomphotherium|Gompotherium]]'' jaw is on display at the University of California Museum of Paleontology, Berkeley.<ref>{{Cite journal |last1=McDaniel |first1=George E. |last2=Jefferson |first2=George T. |date=2006-01-01 |title=Mammoths in our midst: The proboscideans of Anza-Borrego Desert State Park®, Southern California, USA |url=https://www.sciencedirect.com/science/article/pii/S1040618205000601 |journal=Quaternary International |series=Third International Mammoth Conference, Dawson, Yukon |volume=142-143 |pages=124–129 |doi=10.1016/j.quaint.2005.03.011 |bibcode=2006QuInt.142..124M |issn=1040-6182|url-access=subscription }}</ref>
[[File:AnzaMorterosByPhilKonstantin.jpg|thumb|250px|''Morteros'', [[bedrock mortar]] grinding holes, in the Indian Hill area]]

==Native Americans==
The [[Native Americans in the United States|Native Americans]] of the surrounding mountains and deserts include the [[Cahuilla people|Cahuilla]], [[Cupeño people|Cupeño]], and [[Kumeyaay people|Kumeyaay]] (Diegueño) Native American tribes. It was the homeland of these peoples for thousands of years, and their artists created [[petroglyph]] and [[pictogram]] [[rock art]] expressing their cultures.<ref>{{cite web |url=http://www.abdnha.org/04rockart_main.htm |title=Anza-Borrego Native American Rock Art |website=www.abdnha.org |access-date=22 June 2010 |archive-date=2 February 2015 |archive-url=https://web.archive.org/web/20150202162213/http://abdnha.org/04rockart_main.htm |url-status=live }}</ref> Common foods of their diets included the [[Agave deserti]], [[Cylindropuntia fulgida|jumping cholla cactus]], [[Hare|jackrabbit]], [[bighorn sheep]], and Indian rice grasses. Food-processing and harvesting was labor and time intensive. Roasting pits, bedrock milling and grinding features, cupule petroglyphs, and bedrock mortars all lead to this conclusion. Many artifacts have been found, such as [[obsidian]], [[pumice]], and fish bones, which tell us that these communities had extensive regionally internal trade networks. These were all observed at the CA-SDI-813, also known as the Mine Wash Site in Anza-Borrego Desert State Park.<ref>{{Cite web |title=Aboriginal Settlement in Mine Wash, Anza-Borrego Desert State Park |url=https://www.parks.ca.gov/ |access-date=2023-10-25 |website=CA State Parks |language=en}}</ref>

==Park interpretive associations==
The Anza-Borrego Foundation, founded in 1967, is a non-profit educational organization and is the sole [[Cooperating Associations|cooperating association]] of the park. It manages all sales at the State Park Visitor Center and State Park Store.

The Anza-Borrego Institute, the education arm of the foundation, provides in-depth educational courses to more than 100,000 visitors each year. The institute offers in-depth field programs, a fifth-grade environmental camp, citizen science research, and [[Parks Online Resources for Teachers and Students]]. The foundation's mission is to protect and preserve the natural landscapes, wildlife habitat, and cultural heritage of the park for the benefit and enjoyment of present and future generations.<ref>{{cite web |title=Anza-Borrego Foundation |url=http://www.theabf.org |access-date=22 June 2010 |archive-url=https://web.archive.org/web/20100620152230/http://theabf.org/ |archive-date=20 June 2010 <!--DASHBot--> |url-status=live}}</ref>

== Filming locations ==
Notable movies, among others, filmed in the park include:<ref>{{Cite web |last=Jee |first=Fred |date=2024-04-23 |title=Film Plots: Anza Borrego Desert State Park |url=https://www.gotoborregosprings.com/film-plots-anza-borrego-desert-state-park |access-date=2025-10-10 |website=www.gotoborregosprings.com |language=en}}</ref>
* The climactic finale of [[Paul Thomas Anderson]]'s ''[[One Battle After Another]]'', starring [[Leonardo DiCaprio]] and [[Sean Penn]] were filmed in the park.<ref name=":0">{{Cite news |last=Bartlett |first=Amanda |title=Locals spill the secrets of filming 'One Battle After Another' in NorCal |url=https://www.sfgate.com/sf-culture/article/leonardo-dicaprio-movie-northern-california-21051254.php |archive-url=http://web.archive.org/web/20250926211813/https://www.sfgate.com/sf-culture/article/leonardo-dicaprio-movie-northern-california-21051254.php |archive-date=2025-09-26 |access-date=2025-10-10 |work=SFGATE |language=en}}</ref>
* ''[[Last Days in the Desert]] (2014)'' starring [[Ewan McGregor]] as [[Jesus|Jesus Christ]] was filmed in the park.<ref>{{Cite web |last=Verrier |first=Richard |date=2014-03-12 |title=Anza-Borrego Desert is fertile ground for filming |url=https://www.latimes.com/business/la-et-ct-onlocation-last-days-desert-20140312-story.html |url-status=live |archive-url=https://web.archive.org/web/20140520060926/http://articles.latimes.com/2014/mar/12/entertainment/la-et-ct-onlocation-last-days-desert-20140312 |archive-date=2014-05-20 |access-date=2025-10-10 |website=Los Angeles Times |language=en-US}}</ref>
* ''[[Into the Wild (film)|Into the Wild]]'' (2007)
* [[The Island (2005 film)|The Island]] (2005)
* ''[[The Scorpion King]]'' (2002).<ref name=":0" />
* ''[[The Salton Sea (2002 film)|The Salton Sea]]'' (2002)
* ''[[Bugsy]]'' (1991) starring [[Warren Beatty]]<ref name=":0" />
* ''[[The Andromeda Strain]]'' (1971)

==Gallery==
<gallery class="center" caption="Flora and fauna of Anza-Borrego Desert Park">
Image:Bighorn_Sheep-Anza_Borrego.jpg|[[Desert bighorn sheep|Peninsular bighorn sheep]] in Anza-Borrego Desert State Park
Image:Desertflower.JPG|A [[Baileya (plant)|desert marigold]] in bloom
Image:0703Chuckwalla.JPG|Common [[chuckwalla]], ''Sauromalus ater'' in Palm Canyon, near Palm Springs
Image:Ocotillo02262006.JPG|An [[Fouquieria splendens|ocotillo]] plant common in Anza-Borrego Desert State Park
Image: Arecaceae - Washingtonia filifera - California Fan Palm.webm|[[Washingtonia filifera]] in Borrego Palm Canyon. Video clip
Image: Cactaceae - Cylindropuntia bigelovii - Cholla Cactus.webm|[[Cylindropuntia bigelovii]]. Video clip
Image: Cactareae - Ferocactus cylindraceus - Barrel Cactus.webm|[[Ferocactus cylindraceus]]. Video clip
</gallery>

==See also==
* [[Mojave and Colorado Deserts Biosphere Reserve]]
** [[Man and the Biosphere Programme]]
** [[World Network of Biosphere Reserves in Europe and North America#United States of America|World Network of Biosphere Reserves in the United States]]
* [[Mud Caves]]
* [[Ocotillo Wells, California]]
* [[Shelter Valley, California]]

==References==
;Specific
{{Reflist|refs=

<ref name="Barbour 2019">{{Citation |title=23. Colorado Desert Vegetation |date=2019-12-31 |work=Terrestrial Vegetation of California, 3rd Edition |pages=657–682 |editor-last=Barbour |editor-first=Michael |url=https://www.degruyter.com/document/doi/10.1525/9780520933361-025/html |access-date=2024-05-06 |publisher=University of California Press |doi=10.1525/9780520933361-025 |isbn=978-0-520-93336-1 |editor2-last=Keeler-Wolf |editor2-first=Todd |editor3-last=Schoenherr |editor3-first=Allan A.|url-access=subscription }}</ref>

}}

; General
* Hogan, C. Michael (2009). [https://web.archive.org/web/20090930184850/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=90942 ''California Fan Palm: Washingtonia filifera'', GlobalTwitcher.com, ed. Nicklas Stromberg]
* Jefferson, George T. and Lowell Lindsay (2006). ''Fossil Treasures of the Anza-Borrego Desert'' ([[Sunbelt Publications]], San Diego). {{ISBN|0-932653-50-2}}

==Further reading==
* Halford, Robin (2005). ''Hiking in Anza-Borrego Desert: Over 100 Half-Day Hikes'' (Anza Borrego Desert Natural History Association, Borrego Springs). {{ISBN|0-910805-13-X}}
* {{cite book |last=Hogue |first=Lawrence |title=All the Wild and Lonely Places: Journeys in a Desert Landscape |year=2000 |publisher=Shearwater Books (Inland Press) |location=Washington, DC |isbn=978-1559636513 |pages=256 |url=https://books.google.com/books?id=4yLlXAJoD_QC |oclc=43397048}}
* Lindsay, Diana (2001). ''Anza-Borrego A to Z: People, Places, and Things'' ([[Sunbelt Publications]], San Diego). {{ISBN|0-932653-42-1}}
* Lindsay, Lowell, and Diana (2006). ''The Anza-Borrego Desert Region: A Guide to the State Park and Adjacent Areas of the Western Colorado Desert. Fifth Edition'' (Wilderness Press, Berkeley). {{ISBN|0-89997-400-7}}
* ''[[Serenity (2005 film)|Serenity (film)]]'' – location shooting in the park for the 2005 feature film shows the environs.
* {{cite book |last=Wild |first=Peter |title=Marshal South, of Yaquitepec |year=2005 |publisher=The Shady Myrick Research Project |location=[[Johannesburg, California]] |pages=157 |oclc=58796769}} – Marshal South and his wife, Tanya, wrote a series of highly popular "Desert Refuge" articles (1940–1946) for the ''[[Desert Magazine]]'' about their primitive life in the desert. They lived in a home they called ''Yaquitepec'' on a mountaintop named Ghost Mountain near Blair Dry Lake

==External links==
{{Commons category|Anza-Borrego Desert State Park}}
{{Wikivoyage|Anza-Borrego Desert State Park}}
* [http://www.parks.ca.gov/?page_id=638 official ''Anza-Borrego Desert State Park'' website]
* [http://www.theabf.org/ Anza-Borrego Foundation]
* [http://www.abdnha.org/ Anza-Borrego Desert Natural History Association]
* [https://www.nps.gov/juba/index.htm Juan Bautista de Anza National Historic Trail]
* [http://www.anzaborrego.net/ Anza Borrego Tribute]
* [http://www.borregohiking.com/ Anza Borrego Hiking]
* [https://www.flickr.com/porch-photos/sets/72157636487466403/ Fish Creek Wash & Carrizo Badlands]
* [http://www.borregospringschamber.com/ Borrego Springs Chamber & Visitors' Bureau]
* [https://anzaborrego.ucnrs.org/ Steele/Burnand Anza-Borrego Desert Research Center]

{{Clear}}
{{Protected areas of California|SP}}
{{San Diego County, California}}
{{San Diego metropolitan area}}
{{California}}
{{Authority control}}

[[Category:Anza-Borrego Desert State Park|Anza-Borrego Desert State Park]]
[[Category:State parks of California]]
[[Category:Colorado Desert]]
[[Category:Nature centers in California]]
[[Category:Nature reserves in California]]
[[Category:Parks in Imperial County, California]]
[[Category:Parks in Riverside County, California]]
[[Category:Parks in San Diego County, California]]
[[Category:Protected areas of the Colorado Desert]]
[[Category:National Natural Landmarks in California]]
[[Category:Santa Rosa Mountains (California)]]
[[Category:Salton Trough]]
[[Category:1933 establishments in California]]
[[Category:Protected areas established in 1933]]
[[Category:Campgrounds in California]]
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