The Santa Susana Mountains are a

transverse Transverse may refer to: *Transverse engine, an engine in which the crankshaft is oriented side-to-side relative to the wheels of the vehicle *Transverse flute, a flute that is held horizontally * Transverse force (or ''Euler force''), the tangen ...

range of mountains in

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...

, north of the city of

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...

, in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. The range runs east-west, separating the

San Fernando San Fernando may refer to: People *Ferdinand III of Castile (c. 1200–1252), called ''San Fernando'' (Spanish) or ''Saint Ferdinand'', King of Castile, León, and Galicia Places Argentina *San Fernando de la Buena Vista, city of Greater Buenos ...

and Simi valleys on its south from the

Santa Clara River Valley The Santa Clara River Valley is a rural, mainly agricultural, valley in Ventura County, California that has been given the moniker Heritage Valley by the namesake tourism bureau. The valley includes the communities of Santa Paula, Fillmore, Piru ...

to the north and the

Santa Clarita Valley The Santa Clarita Valley (SCV) is part of the upper watershed of the Santa Clara River in Southern California. The valley was part of the Rancho San Francisco Mexican land grant. Located in Los Angeles County, its main population center is th ...

to the northeast. The

Oxnard Plain The Oxnard Plain is a large coastal plain in southwest Ventura County, California, United States surrounded by the mountains of the Transverse ranges. The cities of Oxnard, Camarillo, Port Hueneme and much of Ventura as well as the unincorpora ...

is to the west of the Santa Susana Mountains.

Description

Geography

The

Newhall Pass Newhall Pass is a low mountain pass in Los Angeles County, California. Historically called Fremont Pass and San Fernando Pass, with Beale's Cut, it separates the Santa Susana Mountains from the San Gabriel Mountains. Although the pass was visite ...

separates the Santa Susana Mountains from the

San Gabriel Mountains The San Gabriel Mountains ( es, Sierra de San Gabriel) are a mountain range located in northern Los Angeles County, California, Los Angeles County and western San Bernardino County, California, United States. The mountain range is part of the Tr ...

to the east. Newhall Pass is the major north-south connection between the San Fernando and Santa Clarita valleys, and

Interstate 5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Califor ...

and a railroad line share Newhall Pass. The

Santa Susana Pass The Santa Susana Pass, originally Simi Pass, is a low mountain pass in the Simi Hills of Southern California, connecting the San Fernando Valley and Los Angeles neighborhood of Chatsworth, to the city of Simi Valley and eponymous valley. It h ...

(containing SR 118) connects the Simi and San Fernando valleys, and separates the Santa Susana Mountains from the

Simi Hills The Simi Hills are a low rocky mountain range of the Transverse Ranges in eastern Ventura County and western Los Angeles County, of southern California, United States. Geography The Simi Hills are aligned east-west and run for , and average arou ...

to the south.

Santa Susana Pass State Historic Park Santa Susana Pass State Historic Park is a California State Park of approximately located on the boundary between Ventura and Los Angeles counties, between the communities of Chatsworth and Simi Valley. Geologically, the park is located where ...

is located in the Simi Hills, just south of the Santa Susana Pass, at the northwestern edge of the San Fernando Valley. The Santa Susana Mountains are not as steep or high as the San Gabriel Mountains. The western half of the range lies in

Ventura County Ventura County () is a county in the southern part of the U.S. state of California. As of the 2020 census, the population was 843,843. The largest city is Oxnard, and the county seat is the city of Ventura. Ventura County comprises the Oxnar ...

, and the eastern half lies in

Los Angeles County Los Angeles County, officially the County of Los Angeles, and sometimes abbreviated as L.A. County, is the most populous county in the United States and in the U.S. state of California, with 9,861,224 residents estimated as of 2022. It is the ...

. The southeastern slopes of the Santa Susana Mountains are part of the City of

, and housing subdivisions, including

Porter Ranch Porter Ranch is a suburban neighborhood in the northwest San Fernando Valley region of the City of Los Angeles, California. History New home construction that was completed in the Porter Ranch area in the 1990s–2000s, including the Renaiss ...

, have been built on the lower slopes of the range. The city of

Simi Valley Simi Valley (; Chumash: ''Shimiyi'') is a city in the valley of the same name in the southeast region of Ventura County, California, United States. Simi Valley is from Downtown Los Angeles, making it part of the Greater Los Angeles Area. The ...

lies to the southwest. North of the range is the fast-growing city of

Santa Clarita Santa Clarita (; Spanish for "Little St. Clare") is a city in northwestern Los Angeles County in the U.S. state of California. With a 2020 census population of 228,673, it is the third-largest city by population in Los Angeles County, the 17t ...

, and several large subdivisions in unincorporated Los Angeles County, including Lyons Ranch and

Newhall Ranch Newhall may refer to: __NOTOC__ Places in England *Newhall, Cheshire *Newhall, Derbyshire * Newhall, Essex, an area within Harlow * Newhall, South Yorkshire, an area within Sheffield in the United States * Newhall, Santa Clarita, California, a ...

, have been approved for development. The Sunshine Canyon Landfill is at the mountains' eastern end, and several canyons in the northwest corner of the range have been proposed for more

landfill A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste ...

s. The Santa Susana Mountains are paralleled by

State Route 118 Route 118 or Highway 118 can refer to multiple roads: Argentina * National Route 118 (Argentina), National Route 118 Canada * British Columbia Highway 118 * New Brunswick Route 118 * Nova Scotia Highway 118 * Ontario Highway 118 * Prince ...

to the south and State Route 126 to the north.

Climate

The mountains have a mild climate, with warm, dry summers and cool, wet winters (Mediterranean climate type). Snow falls in winter in some higher areas, such as

Oat Mountain Oat Mountain is a mountain, peak of the Santa Susana Mountains overlooking the San Fernando Valley (near Los Angeles, California) to the south and southeast. Oat Mountain is the highest peak in the Santa Susana Mountains of California. The Los A ...

, but melts quickly. Annual precipitation totals vary between 18 and 25 inches, depending on exposure to the rain-bearing winds. Most of the rain falls between November and March. Because of the summer drought, wildfires sometimes occur in summer and fall before the rains start, especially during hot, dry "Santa Ana" wind events (mostly between late September to mid November).

Peaks

The highest peaks in the range are

(1,142 m; 3,747 feet), Mission Point (845 m; 2,771 feet),

Rocky Peak Rocky Peak, located in Rocky Peak Park, is the fourth-highest point in the Santa Susana Mountains, and overlooks the San Fernando Valley and Chatsworth, the Simi Hills, and the Simi Valley in Southern California. The peak, which is in elevatio ...

(827 m; 2,714 feet), and Sand Rock Peak (765 m; 2,511 feet). The summit of

lies directly atop the line separating Ventura and

counties and is indicated by a battered marker embedded into the

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

boulder summit.

History

The first discovery of

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...

in California was in Pico Canyon, on the north side of the mountains, The California Star Oil Works, later

Chevron Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock ...

, succeeded with '' Pico Well No. 4''. It became famous not only as the first well in California, but also as the longest-producing well in the world, having been capped in September, 1990 after 114 years. Well No. 4 has the distinction of being the first site in Los Angeles County to be listed on the

National Register of Historic Places The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...

, in 1966. The surrounding town,

Mentryville Mentryville was an oil drilling town in the Santa Susana Mountains in Los Angeles County, California, USA. It was started by Charles Alexander Mentry in the 1870s around the newly discovered oil reserves in that area. The first oil strike was ...

, is maintained as the oil "ghost town" Mentryville Historical Park, withi
Pico Canyon Park
Many active oil and gas fields remain in the area, with some of the larger operators including Vintage Production,

Freeport McMoRan Freeport-McMoRan Inc., often called Freeport, is an American mining company based in the Freeport-McMoRan Center, in Phoenix, Arizona. The company is the world's largest producer of molybdenum, is a major copper producer and operates the world's ...

, and the

Southern California Gas Company The Southern California Gas Company (trading as SoCalGas) is a utility company based in Los Angeles, California, and a subsidiary of Sempra Energy. It is the primary provider of natural gas to Los Angeles and Southern California. Overview Its ...

. The largest of SoCalGas's four underground storage natural gas facilities is within the

Aliso Canyon Oil Field The Aliso Canyon Oil Field (also Aliso Canyon Natural Gas Storage Field, Aliso Canyon Underground Storage Facility) is an oil field and natural gas storage facility in the Santa Susana Mountains in Los Angeles County, California, north of the Port ...

north of

. The mountains are within the acquisition area for the

Santa Monica Mountains Conservancy The Santa Monica Mountains Conservancy is an agency of the state of California in the United States founded in 1980 and dedicated to the acquisition of land for preservation as open space, for wildlife and California native plants habitat Natu ...

, which operates several parks, includin
Santa Clarita Woodlands Park
Rocky Peak Park
Joughin Open Space PreserveHappy Camp Canyon Regional Park
and othe
Santa Susana parks
in the Santa Susana Mountains through the Mountains Recreation and Conservation Authority. The City of Los Angeles maintains O'Melveny Park at the eastern end of the mountains. Note: the

Santa Susana Field Laboratory The Santa Susana Field Laboratory (SSFL), formerly known as Rocketdyne, is a complex of industrial research and development facilities located on a portion of Southern California in an unincorporated area of Ventura County in the Simi Hills betw ...

, once operated by and still owned by

Rocketdyne Rocketdyne was an American rocket engine design and production company headquartered in Canoga Park, California, Canoga Park, in the western San Fernando Valley of suburban Los Angeles, California, Los Angeles, in southern California. The Rocke ...

until toxics are cleaned up, is actually in the

, which are adjacent to the south of the Santa Susana Mountains.

Plants and animals

Flora

The south-facing slopes are mostly covered in

Chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It m ...

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, and

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

savanna. The north-facing slopes are home to magnificent oak woodlands and conifer (fir) woodlands, some of which have been protected in the Santa Clarita Woodlands Park and other large open space preserves. The mountains are part of the California chaparral and woodlands

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 ...

. The

s, (''Quercus spp.''), include the

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

coast live oak ''Quercus agrifolia'', the California live oak, or coast live oak, is a highly variable, often evergreen oak tree, a type of live oak, native to the California Floristic Province. It may be shrubby, depending on age and growing location, but is ...

(''Quercus agrifolia''), the

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

valley oak (''Quercus lobata''), and the coastal scrub oak (''Quercus dumosa'') all can be found in the area. Spring

wildflower A wildflower (or wild flower) is a flower that grows in the wild, meaning it was not intentionally seeded or planted. The term implies that the plant probably is neither a hybrid nor a selected cultivar that is in any way different from the ...

s include the redbush monkey flower,

Mariposa lily ''Calochortus'' is a genus of flowering plants in the lily family. The group includes herbaceous, perennial and bulbous species, all native to North America (primarily the Western United States). The genus ''Calochortus'' includes mariposa ...

, and canyon sunflower.

Poison oak Poison oak refers to two plant species in the genus ''Toxicodendron,'' both of which can cause skin irritation: *''Toxicodendron diversilobum'' or Western poison oak, found in western North America *''Toxicodendron pubescens ''Toxicodendron pub ...

is also an important member of the native plant habitat community. Various ferns are found in moister and tree-shaded areas.

Fauna

Many bird species thrive in the Santa Susana Mountains. Perhaps the most common raptors observed soaring over the brushy, boulder-strewn landscape are

turkey vulture The turkey vulture (''Cathartes aura'') is the most widespread of the New World vultures. One of three species in the genus '' Cathartes'' of the family Cathartidae, the turkey vulture ranges from southern Canada to the southernmost tip of Sout ...

red-tailed hawk The red-tailed hawk (''Buteo jamaicensis'') is a bird of prey that breeds throughout most of North America, from the interior of Alaska and northern Canada to as far south as Panama and the West Indies. It is one of the most common members with ...

s, and

American kestrel The American kestrel (''Falco sparverius''), also called the sparrow hawk, is the smallest and most common falcon in North America. It has a roughly two-to-one range in size over subspecies and sex, varying in size from about the weight of ...

s. In oak woodlands it is not uncommon to see

red-shouldered hawk The red-shouldered hawk (''Buteo lineatus'') is a medium-sized buteo. Its breeding range spans eastern North America and along the coast of California and northern to northeastern-central Mexico. It is a permanent resident throughout most of its ...

s flying from limb to limb. Through the cover of dense, trailside chaparral you might glimpse the

California towhee The California towhee (''Melozone crissalis'') is a bird of the family Passerellidae, native to the coastal regions of western Oregon and California in the United States and Baja California Sur in Mexico. The taxonomy of this species has been deb ...

or the colorful

spotted towhee The spotted towhee (''Pipilo maculatus'') is a large New World sparrow. The taxonomy of the towhees has been debated in recent decades, and until 1995 this bird and the eastern towhee were considered a single species, the rufous-sided towhee. A ...

, birds who often make their presence known by rustling up leaf litter on the ground.

California quail The California quail (''Callipepla californica''), also known as the California valley quail or Valley quail, is a small ground-dwelling bird in the New World quail family. These birds have a curving crest or '' plume'', made of six feathers, tha ...

greater roadrunner The greater roadrunner (''Geococcyx californianus'') is a long-legged bird in the cuckoo family, Cuculidae, from the Aridoamerica region in the Southwestern United States and Mexico. The scientific name means "Californian earth-cuckoo". Along wit ...

, and

common raven The common raven (''Corvus corax'') is a large all-black passerine bird. It is the most widely distributed of all corvids, found across the Northern Hemisphere. It is a raven known by many names at the subspecies level; there are at least ...

are also residents of the range. The eerie and enchanting call of the

common poorwill The common poorwill (''Phalaenoptilus nuttallii'') is a nocturnal bird of the family Caprimulgidae, the nightjars. It is found from British Columbia and southeastern Alberta, through the western United States to northern Mexico. The bird's habi ...

can often be heard after dark while quick eyes might observe the silent flight of

great horned owl The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air"), or the hoot owl, is a large owl native to the Americas. It is an extrem ...

s and phantom-like barn owls. A handful of fascinating amphibians live in the area. Streams and creeks support populations of

Pacific tree frog The Pacific tree frog (''Pseudacris regilla''), also known as the Pacific chorus frog, has a range spanning the Pacific Northwest, from Northern California, Oregon, and Washington to British Columbia in Canada and extreme southern Alaska. They l ...

, the small amphibian whose signature chorus adds an aura of mystery and inexplicable beauty to the surrounding land.

Western toad The western toad (''Anaxyrus boreas'') is a large toad species, between long, native to western North America. ''A. boreas'' is frequently encountered during the wet season on roads, or near water at other times. It can jump a considerable distan ...

s often make their appearance at nightfall, emerging from burrows in search of water and insects, while

California slender salamander The California slender salamander (''Batrachoseps attenuatus'') is a lungless salamander Stebbins, Robert C. (2003). ''A Field Guide to Western Reptiles and Amphibians'', 3rd Edition. Houghton Mifflin Company, that is found primarily in coastal ...

s are often found under the cool leaf litter and canopy of oak woodlands. Many reptiles thrive in the Santa Susana range. Lizards that are likely to be observed on any given day include the common

western fence lizard The western fence lizard (''Sceloporus occidentalis'') is a common lizard of Arizona, New Mexico, California, Idaho, Nevada, Oregon, Utah, Washington, Northern Mexico, and the surrounding area. As the ventral abdomen of an adult is characterist ...

and the equally abundant

side-blotched lizard Side-blotched lizards are lizards of the genus ''Uta''. They are some of the most abundant and commonly observed lizards in the deserts of western North America, known for cycling between three colorized breeding patternsSinervo, B.; C.M. Lively ...

. Somewhat less frequently observed but still present are the

southern alligator lizard The southern alligator lizard (''Elgaria multicarinata'') is a common species of lizard in the Family (biology), family Anguidae. The species is native to the Pacific coast of North America. It ranges from Baja California to the state of Washingt ...

western skink The western skink ''(Plestiodon skiltonianus)'' is a species of small, smooth- scaled lizard with relatively small limbs. It measures about 100 to 210 mm (about 4 to 8.25 inches) in total length (body + tail). It is one of seven species of ...

, whiptail, and the seemingly rare

coast horned lizard The coast horned lizard (''Phrynosoma coronatum'') is a species of phrynosomatid lizard endemic to Baja California Sur in Mexico. As a defense the lizard can shoot high pressure streams of blood out of its eyes if threatened. Taxonomy It was ...

Southern Pacific rattlesnake ''Crotalus helleri'', known as the Southern Pacific rattlesnake, black diamond rattlesnake,Albert Hazen WWright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a div ...

s and

gopher snake ''Pituophis'' is a genus of non venomous colubrid snakes, commonly referred to as gopher snakes, pine snakes, and bullsnakes, which are endemic to North America. Geographic range Species and subspecies within the genus ''Pituophis'' are found t ...

s are perhaps the most commonly observed snakes, but a lucky hiker might also encounter other species including the striped racer,

California kingsnake The California kingsnake (''Lampropeltis californiae'') is a nonvenomous colubrid snake endemic to the western United States and northern Mexico, and is found in a variety of habitats. Due to ease of care and a wide range of color variations, the ...

, and ring-necked snake. Mammals that may be regularly observed in the mountains include smaller animals such as the California ground squirrel and brush rabbit. Small mammals that are less often seen include the

dusky-footed woodrat The dusky-footed woodrat (''Neotoma fuscipes'') is a species of nocturnal rodent in the family Cricetidae. They are commonly called "packrats" or "trade rats" and build large, domed dens that can reach several feet in height. Coyotes and other ...

and the agile kangaroo rat. As for larger mammals, the well-trained eye might spot

California mule deer The California mule deer (''Odocoileus hemionus californicus'') is a subspecies of mule deer whose range covers much of the state of California. Anatomy One of the principal means of distinguishing the closely related black-tailed deer and whi ...

or a

coyote The coyote (''Canis latrans'') is a species of canis, canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecologica ...

. Larger mammals that are considerably more secretive and therefore less often encountered include the

gray fox The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (''Urocyon littor ...

bobcat The bobcat (''Lynx rufus''), also known as the red lynx, is a medium-sized cat native to North America. It ranges from southern Canada through most of the contiguous United States to Oaxaca in Mexico. It is listed as Least Concern on the IUC ...

ring-tailed cat The ringtail (''Bassariscus astutus'') is a mammal of the raccoon family native to arid regions of North America. It is widely distributed and well adapted to disturbed areas. It has been legally trapped for its fur. It is listed as Least Co ...

American badger The American badger (''Taxidea taxus'') is a North American badger similar in appearance to the European badger, although not closely related. It is found in the western, central, and northeastern United States, northern Mexico, and south-cent ...

, and the

mountain lion The cougar (''Puma concolor'') is a large cat native to the Americas. Its range spans from the Canadian Yukon to the southern Andes in South America and is the most widespread of any large wild terrestrial mammal in the Western Hemisphere. ...

. A population of

American black bear The American black bear (''Ursus americanus''), also called simply a black bear or sometimes a baribal, is a medium-sized bear endemic to North America. It is the continent's smallest and most widely distributed bear species. American black bear ...

s occupy various niches in the backcountry; showing up in communities below the mountains every few years. The mountains are part of the Southern California coastal

wildlife corridor A wildlife corridor, habitat corridor, or green corridor is an area of habitat connecting wildlife populations separated by human activities or structures (such as roads, development, or logging). This allows an exchange of individuals between ...

the connects Los Padres National Forest with the Santa Monica Mountains.

Rim of the Valley Trail

Th
Rim of the Valley Trail
is a plan in progress for connecting the parkland and recreational areas of the San Fernando, Simi, and La Crescenta Valleys via the Santa Susana Mountains. Rocky Peak Park and O'Melveny Park have trail sections already.

References

External links

SMMC: Parks in the Santa Susana Mountains
- ''with park links, by

.''
Santa Susana Mountain Park AssociationOfficial Santa Susana Pass State Park websiteRim of the Valley TrailNPS: Rim of the Valley Corridor Study
- ''

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propertie ...

project'' {{Santa Clara River Transverse Ranges Mountain ranges of Los Angeles County, California Mountain ranges of Ventura County, California Geography of the San Fernando Valley Geography of Simi Valley, California Chatsworth, Los Angeles Granada Hills, Los Angeles Moorpark, California Porter Ranch, Los Angeles Mountain ranges of Southern California