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 tange ...

range of mountains in

Southern California Southern California (commonly shortened to SoCal) is a geographic and 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 populous urban ...

, 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 Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. The range runs east-west, separating the San Fernando and Simi valleys on its south from the Santa Clara River Valley 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 unincorpo ...

is to the west of the Santa Susana Mountains.

Description

Geography

The Newhall Pass 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 and western San Bernardino County, California, United States. The mountain range is part of the Transverse Ranges and lies betw ...

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 Californi ...

and a railroad line share Newhall Pass. The Santa Susana Pass (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 aro ...

to the south. Santa Susana Pass State Historic Park 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 (United States), county in Southern California, the southern part of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 843,843. The largest city is Oxnard, California ...

, 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 List of the most populous counties in the United States, most populous county in the United States and in the U.S. state of California, ...

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

, and housing subdivisions, including Porter Ranch, have been built on the lower slopes of the range. The city of Simi Valley lies to the southwest. North of the range is the fast-growing city of Santa Clarita, and several large subdivisions in unincorporated Los Angeles County, including Lyons Ranch and Newhall Ranch, 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 wast ...

s. The Santa Susana Mountains are paralleled by State Route 118 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, 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 Oat Mountain (1,142 m; 3,747 feet), Mission Point (845 m; 2,771 feet), Rocky Peak (827 m; 2,714 feet), and Sand Rock Peak (765 m; 2,511 feet). The summit of Rocky Peak 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 silicat ...

boulder summit.

History

The first discovery of oil 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 la ...

, 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 ...

, 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, 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 north of Porter Ranch. 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 Natur ...

, 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 O'Melveny Park is a public park located in the Santa Susana Mountains, in the Granada Hills community of the northern San Fernando Valley, in the northernmost portion of the City of Los Angeles, California. History The park is named after Henry ...

at the eastern end of the mountains. Note: the Santa Susana Field Laboratory, once operated by and still owned by

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

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 Mediterranea ...

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 ...

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 na ...

s, and oak 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 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 ...

. The oaks, (''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, whic ...

coast live oak (''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, ...

valley oak ''Quercus lobata'', commonly called the valley oak or roble, grows into the largest of California oaks. It is endemic to California, growing in interior valleys and foothills from Siskiyou County to San Diego County. Mature specimens may attain ...

(''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 mariposas ...

, 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 So ...

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 wit ...

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 or the colorful spotted towhee, birds who often make their presence known by rustling up leaf litter on the ground. California quail, greater roadrunner, 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 extre ...

s and phantom-like

barn owl The barn owl (''Tyto alba'') is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for the polar and desert regions, Asia north of the Himala ...

s. A handful of fascinating amphibians live in the area. Streams and creeks support populations of Pacific tree frog, 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,

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, Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a division of Corn ...

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 ''Diadophis punctatus'', commonly known as the ring-necked snake or ringneck snake, is a harmless species of colubrid snake found throughout much of the United States, central Mexico, and south-eastern Canada. Ring-necked snakes are secretive, no ...

. Mammals that may be regularly observed in the mountains include smaller animals such as the

California ground squirrel The California ground squirrel (''Otospermophilus beecheyi''), also known as the Beechey ground squirrel, is a common and easily observed ground squirrel of the western United States and the Baja California Peninsula; it is common in Oregon and ...

and

brush rabbit The brush rabbit (''Sylvilagus bachmani''), or western brush rabbit, or Californian brush rabbit, is a species of cottontail rabbit found in western coastal regions of North America, from the Columbia River in Oregon to the southern tip of the ...

. Small mammals that are less often seen include the dusky-footed woodrat and the

agile kangaroo rat The agile kangaroo rat (''Dipodomys agilis'') is a species of rodent in the family Heteromyidae. It is endemic to southern California in the United States. Relatively little information has been published on the natural history, life histor ...

. 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 whit ...

or a

coyote The coyote (''Canis latrans'') is a species of 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 ecological nich ...

. 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 ...

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-ce ...

, and the mountain lion. 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

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 properti ...

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