The San Joaquin Hills are a low
mountain range
A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
of the
Peninsular Ranges
The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...
System, located in coastal
Orange County, California
Orange County is located in the Los Angeles metropolitan area in Southern California. As of the 2020 census, the population was 3,186,989, making it the third-most-populous county in California, the sixth-most-populous in the United States, a ...
.
They extend in a northwest–southeast direction, starting in the northwest in
Newport Beach
Newport Beach is a coastal city in South Orange County, California. Newport Beach is known for swimming and sandy beaches. Newport Harbor once supported maritime industries however today, it is used mostly for recreation. Balboa Island, Newport ...
at the southern edge of the
Los Angeles Basin
The Los Angeles Basin is a sedimentary basin located in Southern California, in a region known as the Peninsular Ranges. The basin is also connected to an anomalous group of east-west trending chains of mountains collectively known as the Tr ...
, and extending southeast to
San Juan Capistrano
San Juan Capistrano (Spanish for "St. John of Capistrano") is a city in Orange County, California, located along the Orange Coast. The population was 34,593 at the 2010 census.
San Juan Capistrano was founded by the Spanish in 1776, when St. ...
.
Geography and habitats
Named summits in the San Joaquin Hills include (from north to south)
French Hill in
Turtle Rock,
Irvine Irvine may refer to:
Places On Earth Antarctica
*Irvine Glacier
*Mount Irvine (Antarctica)
Australia
*Irvine Island
*Mount Irvine, New South Wales
Canada
*Irvine, Alberta
* Irvine Inlet, Nunavut
United Kingdom
*Irvine, North Ayrshire, Scotla ...
;
Signal Peak and
Pelican Hill, both of which are near the
Newport Coast
Newport Coast is a community south of the main body of the city of Newport Beach, California. It was a separate census-designated place in Orange County, California, United States, until 2001, when it was annexed into Newport Beach. Newport Beach ...
neighborhood of Newport Beach;
Temple Hill in
Laguna Beach
Laguna Beach (; ''Laguna'', Spanish for "Lagoon") is a seaside resort city located in southern Orange County, California, in the United States. It is known for its mild year-round climate, scenic coves, environmental preservation efforts, and a ...
, more commonly known as "
Top of the World" after the neighborhood on its peak;
and Niguel Hill in
Laguna Niguel
Laguna Niguel () is a city in Orange County, California, United States. The name Laguna Niguel is derived from the words "Laguna" (Spanish for "lagoon") and "Niguili" (the name of a Native American village once located near Aliso Creek). As of ...
.
Geology
A
fault line
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
, the San Joaquin Hills
blind thrust, lies eight miles below the hills. Scientists have suggested that the San Joaquin Hills have been formed by uplift from this fault.
The main ridge of the San Joaquin Hills runs southeast from the
Upper Newport Bay
The Upper Newport Bay (known locally as "The Back Bay") is a large coastal wetland (an estuary) in Newport Beach, Southern California and a major stopover for birds on the Pacific Flyway. Dozens of species, including endangered ones, can be ob ...
area, attaining its maximum height of roughly near
Laguna Beach
Laguna Beach (; ''Laguna'', Spanish for "Lagoon") is a seaside resort city located in southern Orange County, California, in the United States. It is known for its mild year-round climate, scenic coves, environmental preservation efforts, and a ...
. Many of the high ridges exceed in height. The hills stretch over a distance of about and can be up to broad. In many places, the San Joaquin Hills drop directly into the Pacific Ocean, creating the steep
sea cliff
Seacliff or Sea Cliff or Sea Cliffe may refer to:
;Places
''Australia''
*Seacliff, South Australia, suburb of Adelaide
*Seacliff Park, South Australia, a suburb of Adelaide
*Sea Cliff Bridge, in Illawarra, New South Wales
''New Zealand''
*Seacli ...
s that characterize the region. Streams that originate on the west slope of the range include Buck Gully, Los Trancos Creek, Muddy Creek, El Moro Creek, Emerald Creek, Prima Deshecha Cañada, Segunda Deshecha Cañada, and
Christianitos Canyon. The east side is drained by Bonita Creek,
Sand Canyon Wash, San Joaquin Wash, and La Cañada Wash. Cities bordering the range include Newport Beach,
Irvine Irvine may refer to:
Places On Earth Antarctica
*Irvine Glacier
*Mount Irvine (Antarctica)
Australia
*Irvine Island
*Mount Irvine, New South Wales
Canada
*Irvine, Alberta
* Irvine Inlet, Nunavut
United Kingdom
*Irvine, North Ayrshire, Scotla ...
,
Laguna Hills
Laguna Hills (; ''Laguna'', Spanish for "Lagoon") is a city in south Orange County, California, United States. Its name refers to its proximity to Laguna Canyon and the much older Laguna Beach. Other newer cities nearby—Laguna Niguel and Lagun ...
,
Aliso Viejo
Aliso Viejo (Spanish for "Old Sycamore") is a city in the San Joaquin Hills of southern Orange County, California. It had a population of 47,823 as of the 2010 census, up from 40,166 as of the 2000 census. It became Orange County's 34th city on ...
, Laguna Beach,
Laguna Niguel
Laguna Niguel () is a city in Orange County, California, United States. The name Laguna Niguel is derived from the words "Laguna" (Spanish for "lagoon") and "Niguili" (the name of a Native American village once located near Aliso Creek). As of ...
,
Dana Point
Dana Point () is a city located in southern Orange County, California, United States. The population was 33,107 at the 2020 census. It has one of the few harbors along the Orange County coast, and with ready access via State Route 1, it is a po ...
,
San Juan Capistrano
San Juan Capistrano (Spanish for "St. John of Capistrano") is a city in Orange County, California, located along the Orange Coast. The population was 34,593 at the 2010 census.
San Juan Capistrano was founded by the Spanish in 1776, when St. ...
, and
San Clemente
San Clemente (; Spanish for " St. Clement") is a city in Orange County, California. Located in the Orange Coast region of the South Coast of California, San Clemente's population was 64,293 in at the 2020 census. Situated roughly midway betwee ...
.
Because of erosion phenomena during the previous
Ice Age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...
, the San Joaquin Hills are not one continuous mountain range, but instead are bisected by numerous
water gap
A water gap is a gap that flowing water has carved through a mountain range or mountain ridge and that still carries water today. Such gaps that no longer carry water currents are called wind gaps. Water gaps and wind gaps often offer a prac ...
s cut by rivers flowing southwest from the
Santa Ana Mountains
The Santa Ana Mountains are a short peninsular mountain range along the coast of Southern California in the United States. They extend for approximately southeast of the Los Angeles Basin largely along the border between Orange and Riverside co ...
. In the north, Newport Bay was formed by the
Santa Ana River
The Santa Ana River is the largest river entirely within Southern California in the United States. It rises in the San Bernardino Mountains and flows for most of its length through San Bernardino and Riverside Counties, before cutting through ...
switching its course to the south, cutting across the northern part of the range.
Laguna Canyon
Laguna Canyon (also called Cañada de las Lagunas, meaning "Lake Canyon" in Spanish) is a canyon that cuts through the San Joaquin Hills in southern Orange County, California, in the United States, directly south of the city of Irvine. The canyo ...
was formed by
San Diego Creek
San Diego Creek is a urban waterway flowing into Upper Newport Bay in Orange County, California in the United States. Its watershed covers in parts of eight cities, including Irvine, Tustin, and Costa Mesa. From its headwaters in Laguna Woo ...
, but eventually the larger creek changed course and left a
wind gap
A wind gap (or air gap) is a gap through which a waterway once flowed that is now dry as a result of stream capture. A water gap is a similar feature, but one in which a waterway still flows. Water gaps and wind gaps often provide routes which ...
through the hills. The largest canyon by far is
Aliso Canyon
Aliso Canyon is a canyon located in Orange County, California in the United States. The canyon is a water gap across the San Joaquin Hills carved out by Aliso Creek, possibly as recently as the last ice age. Located in a semi-arid climate, it ...
, cut by
Aliso Creek. Further south, the hills dissipate into smaller ridges and are bisected by the canyon of
Salt Creek. The southern extent of the hills are cut by
San Juan Creek
San Juan Creek, also called the San Juan River, is a long stream in Orange and Riverside Counties, draining a watershed of .7.5 Minute Quadrangle Map, U.S. Geological Survey, San Juan Capistrano, 1968, photorevised 1981 Its mainstem begins in ...
.
Flora and fauna
The native vegetation of the hills is in the
California coastal sage and chaparral
The California coastal sage and chaparral ( es, Salvia y chaparral costero de California) is a Mediterranean forests, woodlands, and scrub ecoregion located in southwestern California (United States) and northwestern Baja California (Mexico). It i ...
and
California chaparral and woodlands
The California chaparral and woodlands is a terrestrial ecoregion of southwestern Oregon, northern, central, and southern California (United States) and northwestern Baja California (Mexico), located on the west coast of North America. It is a ...
ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
s, largely
coastal sage scrub
Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is w ...
, but other habitat types include
grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
s,
oak woodlands,
wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
s, and
riparian
A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s along several streams.
In past ages the land that is now the San Joaquin Hills lay under the ocean: construction for the San Joaquin Hills Toll Road unearthed a number of artifacts and more than 40,000 fossils, up to 35 million years old, including 5-million-year-old fossilized whales.
History
Prior to the arrival of Europeans in the area, residents of the nearby
Tongva
The Tongva ( ) are an Indigenous people of California from the Los Angeles Basin and the Southern Channel Islands, an area covering approximately . Some descendants of the people prefer Kizh as an endonym that, they argue, is more historically ...
and
Acjachemen
The Acjachemen (, alternate spelling: Acagchemem) are an Indigenous people of California. They historically lived south of what is known as Aliso Creek and north of the Las Pulgas Canyon in what are now the southern areas of Orange County and t ...
village of
Genga frequented the hills.
The hills take their name from
Rancho San Joaquin
Rancho San Joaquin, the combined Rancho Cienega de las Ranas and Rancho Bolsa de San Joaquin, was a Mexican land grant in the San Joaquin Hills, within present-day Orange County, California.
It was granted to José Antonio Andres Sepúlved ...
, owned by
Jose Andres Sepulveda. Formed in 1842 by the merger of two smaller ranches, this ranch included the northern part of the hills and likely had Laguna Canyon as its southeastern boundary. Rancho San Joaquin later became part of the
Irvine Ranch
The Irvine Company LLC is an American private company focused on real estate development. It is headquartered in Newport Beach, California, with a large portion of its operations centered in and around Irvine, California, a planned city of more ...
. Mexican
Rancho Niguel was located in the southeastern section of the hills.
The San Joaquin Hills blind thrust may be the source of the earliest recorded
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
in California, a large earthquake felt in what is now northern Orange County on July 28, 1769, by
Gaspar de Portolá
Gaspar de Portolá y Rovira (January 1, 1716 – October 10, 1786) was a Spanish military officer, best known for leading the Portolá expedition into California and for serving as the first List of governors of California before 1850, Governor ...
.
[; . Listed by the ]United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
as the earliest recorded earthquake in California on thei
Earthquake Facts
web page.
Development
Two neighborhoods within the San Joaquin Hills take the name of the hills for their own:
San Joaquin Hills, Newport Beach, California, a former
census-designated place
A census-designated place (CDP) is a concentration of population defined by the United States Census Bureau for statistical purposes only.
CDPs have been used in each decennial census since 1980 as the counterparts of incorporated places, such ...
annexed to the city of
Newport Beach
Newport Beach is a coastal city in South Orange County, California. Newport Beach is known for swimming and sandy beaches. Newport Harbor once supported maritime industries however today, it is used mostly for recreation. Balboa Island, Newport ...
, and
San Joaquin Hills, Laguna Niguel, California, a master-planned community located in the city of
Laguna Niguel
Laguna Niguel () is a city in Orange County, California, United States. The name Laguna Niguel is derived from the words "Laguna" (Spanish for "lagoon") and "Niguili" (the name of a Native American village once located near Aliso Creek). As of ...
. Other neighborhoods set in and named after hills in this range include
University Hills University Hills may refer to:
*University Hills, Irvine, California
University Hills is a housing development on the campus of the University of California, Irvine (UCI) in southern Irvine, California, United States, consisting of 1226 for-sale ...
and
Turtle Rock in
Irvine Irvine may refer to:
Places On Earth Antarctica
*Irvine Glacier
*Mount Irvine (Antarctica)
Australia
*Irvine Island
*Mount Irvine, New South Wales
Canada
*Irvine, Alberta
* Irvine Inlet, Nunavut
United Kingdom
*Irvine, North Ayrshire, Scotla ...
.
State Route 73, also called the San Joaquin Hills Toll Road, extends through the length of the hills from Newport Beach to San Juan Capistrano.
State Route 133 crosses the hills through Laguna Canyon in Laguna Beach, and they are also crossed in several other places by less major roads.
See also
*
*
References
{{reflist, 3
Hills of California
Mountain ranges of Orange County, California
Peninsular Ranges
Irvine, California
Laguna Beach, California
Laguna Hills, California
Laguna Niguel, California
Newport Beach, California
Mountain ranges of Southern California
Buried rupture earthquakes