Simi Hills

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Simi Hills
Lang Ranch Oakbrook North Ranch Thousand Oaks July 2021 004.jpg
Main ridge of Simi Peak, highest summit of the Simi Hills
Highest point
PeakSimi Peak
Elevation 2,139 ft (652 m)
Geography
Relief map of California.png
Red triangle with thick white border.svg
Simi Hills
location of Simi Hills in California [1]
CountryUnited States
StateCalifornia
Districts
Range coordinates 34°13′28.015″N118°43′0.326″W / 34.22444861°N 118.71675722°W / 34.22444861; -118.71675722
Topo map USGS  Calabasas

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.

Contents

Geography

The Simi Hills are aligned east-west and run for 26 miles (42 km), and average around 7 mi (11 km) north-south. The Simi Hills are part of the central Transverse Ranges System. [2] They lie almost entirely within southeastern Ventura County, with some southern and eastern foothills within western Los Angeles County.

The Simi Hills are on the western edge of the San Fernando Valley. The Simi Valley lies to the north, and the Conejo Valley lies to the southwest. The San Fernando Valley communities of Chatsworth, West Hills, and Woodland Hills are in the eastern hills and adjacent valley floor in Los Angeles city and county. The cities of Agoura Hills and Westlake Village are also located in Los Angeles County, generally southwest of the Simi Hills. The cities of Thousand Oaks (to the west) and Simi Valley city (to the north) are in the hills and adjacent valleys within Ventura County.

The two nearby mountain ranges are: the higher Santa Susana Mountains adjacent on the northeast across Santa Susana Pass; and the Santa Monica Mountains running nearby along the south.

Watersheds

The hills provide the complete or partial watersheds for several year-round creeks and numerous seasonal streams. They include Las Virgenes Creek (tributary of Malibu Creek), Moore's Canyon Creek, Bell Creek, Dayton Creek, Woolsey Canyon Creek, Brandeis Creek, Runkle Canyon Creek, Arroyo Simi, Palo Comado Creek, Cheeseboro Creek, and Arroyo Calabasas (northern fork). Bell Creek and Arroyo Calabasas are the headwaters of the Los Angeles River, by name its beginning with their confluence in nearby Canoga Park. 90% of the Santa Susana Field Lab property drains into the Los Angeles River via tributaries.

Peaks

Peaks in this region include Simi Peak, 2,403 ft (732 m), [3] Chatsworth Peak, 2,314 ft (700 m), [4] and Escorpión Peak (aka: Castle Peak), 1,475 ft (450 m).

Lang Ranch Oakbrook North Ranch Thousand Oaks May 2019 panorama 5.jpg
View of Simi Hills looking south from Oakbrook Regional Park, with the Santa Monica Mountains in the distance.
Simi Hills.jpg
Panoramic view of the Simi Hills looking north from the Santa Monica Mountains.

Climate

Because of its low elevation, the Simi Hills typically experience rainy, mild winters. Snow is rare in the Simi Hills, even in the highest areas. Summers are warm and dry and wildfires do occur here. Cool winds from the Pacific Ocean come from the Oxnard Plain and blow into the inland areas through the Santa Clara River Valley and the Conejo Valley, though some low hills, such as Conejo Mountain, block these winds from the Conejo Valley. The Simi Hills further block these winds, which bring cool weather in both summer and winter from the San Fernando Valley.

Flora and fauna

Flora

The southern lower hills are mostly covered in grasslands and oak savanna. The northern rocky hills area is primarily chaparral shrubland and oak woodlands. The Simi Hills are part of the California chaparral and woodlands ecoregion. The oaks (Quercus spp.) include: the evergreen coastal live oak ( Quercus agrifolia ), the deciduous valley oak ( Quercus lobata ), and the scrub oak ( Quercus dumosa ). Riparian zone plants include California sycamores (Platanus racemosa) and arroyo willows (Salix lasiolepis). Spring wildflowers include the redbush monkey flower (Mimulus aurantiacus), Plummer's mariposa lily (Calochortus plummerae), and canyon sunflower (Encelia californica). poison oak (Toxicodendron diversilobum) is also an important member of the native plant habitat community here.

Fauna

The Simi Hills is the principal, and much wider, of only two terrestrial wildlife corridors linking the coastal Santa Monica Mountains with the inland Santa Susana Mountains, Topatopa Mountains, and San Gabriel Mountains, all of the transverse ranges fauna community. The Simi Hills are a critical wildlife corridor linkage for the Santa Monica Mountains to these and other Transverse Ranges further east. The undeveloped native habitat provides routes that protect larger land wildlife of the Santa Monicas from genetic isolation. [5] [6] The Wallis Annenberg Wildlife Crossing is a proposed vegetated overpass spanning the Ventura Freeway at Liberty Canyon in Agoura Hills, California.

Large sections of the Simi Hills are protected by parks and open space preserves. The Santa Susana Field Laboratory property, a crucial wildlife corridor to the Santa Susanas, has been proposed for public open space parkland after the closed site's cleanup completion.

The population of red-legged frogs is small and isolated, and was impacted by the Woolsey Fire swept through the area in November 2018. [7]

History

The Simi Hills were inhabited for over 8,000 years by Paleo-indians and Chumash-Venturaño Native Americans for settlements and hunting grounds. [8] [9] The Chumash had the established village of Hu'wam in Cañon del Escorpión (Bell Canyon). It was a multicultural 'crossroads' destination, where Chumash, Tongva, and Tataviam peoples traded and lived beside Bell Creek below Escorpión Peak, at the present day Bell Canyon Park. [10] [11] This peak in the Simi Hills (aka: Castle Peak) is one of nine alignment points in Chumash territory and is essential to maintaining the balance of the natural world. [12] Upstream were healing springs and are rock outcrop 'grinding stones.' The Burro Flats Painted Cave, an example of the Rock art of the Chumash people, is nearby.[ citation needed ]

The Juan Bautista de Anza expedition passed through the area in 1769, being the first European sighting of the Simi Hills. The U.S. National Park Service administers the Juan Bautista de Anza National Historic Trail which enters at Moore Canyon in El Escorpión Park and crosses across the southern Hills through Upper Las Virgenes Canyon Open Space Preserve and Cheeseboro/Palo Comado Canyon Park to the Conejo Valley. [13] In 1845 the land grant for Rancho El Escorpión, beside the Peak and named for it, was issued to one Chumash and two Tongva people and a rare instance of Native Americans being grantees, by Mexican Governor Pío Pico. The Rancho El Conejo was to the west, and included that end of the Simi Hills.[ citation needed ]

In the first half of the 20th century, there were four large movie ranches in the Simi Hills for filming motion pictures on location. The gated community of Bell Canyon began development of geographic Bell Canyon in the 1968. To the north of U.S. 101, east of Thousand Oaks, and west of Simi Valley the early 1960s suburban expansion of metropolitan Los Angeles brought the development of small to significantly sized parcels of land in the Simi Hills. Hillside subdivisions regraded natural contours into terraced lots, changing the Hills viewshed, drainage patterns, and habitats in those areas. The extensive planned new community projects at Jordan Ranch and Ahmanson Ranch were eventually stopped by local citizens and the Santa Monica Mountains Conservancy keeping extensive Hills acreage natural in open space parks.[ citation needed ]

The Simi Hills were home of the Rocketdyne Santa Susana Field Laboratory (SSFL) for open-air testing of rocket engines from 1947 to 1990, and the site of experimental nuclear reactor experiments with four nuclear accidents between 1959 and 1969; these projects and accidents were declassified in 1989. The first accident, in 1959, was the most serious with a full meltdown. The extent of the accident is unknown due to instrument limitations, other than that it released extensive radiation. More radiation was released in the 1959 event than in the Three Mile Island accident 20 years later. [14] The groundwater under portions of the Simi Hills, contaminated with toxins and radionuclides that were also historically used at SSFL, has been and is a key concern in new development decisions and the SSFL property's future limited to parkland use after an impending cleanup, initiating preservation of more open space in the range. [15]

The Rim of the Valley Trail Corridor [16] is in the planning stages and includes the Simi Hills open space parklands and proposed new areas. [17] [18] [19] [20]

Parks

Nearby ranges

See also

Related Research Articles

<span class="mw-page-title-main">Chatsworth, Los Angeles</span> Neighborhood of Los Angeles in California, United States

Chatsworth is a suburban neighborhood in Los Angeles, California, in the San Fernando Valley.

<span class="mw-page-title-main">Santa Monica Mountains</span> Mountain range in California, United States

The Santa Monica Mountains are a coastal mountain range in Southern California, next to the Pacific Ocean. It is part of the Transverse Ranges. The Santa Monica Mountains National Recreation Area encompasses this mountain range. Because of its proximity to densely populated regions, it is one of the most visited natural areas in California.

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 Nature Preserves, and for public recreation activities.

<span class="mw-page-title-main">Santa Susana Mountains</span> Mountain range of the Transverse Ranges in California, United States

The Santa Susana Mountains are a transverse range of mountains in Southern California, north of the city of Los Angeles, in the United States. 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 to the northeast. The Oxnard Plain is to the west of the Santa Susana Mountains.

<span class="mw-page-title-main">West Hills, Los Angeles</span> Neighborhood in Los Angeles, California, United States

West Hills is a neighborhood in the western San Fernando Valley region of the city of Los Angeles, California. It is bordered by mountain ranges to the west and the Los Angeles neighborhoods of Chatsworth to the north, Canoga Park to the east, and Woodland Hills to the south.

<span class="mw-page-title-main">Santa Susana Pass</span> Mountain pass in Los Angeles County, California, United States

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.

<span class="mw-page-title-main">El Escorpión Park</span> Park in the American state of California

El Escorpión Park is a three-acre park located in the Simi Hills of the western San Fernando Valley, in the West Hills district of Los Angeles, California. The park contains the geographic landmark known as Escorpión Peak or Castle Peak, a 1,475-foot-tall rocky peak seen from most parts of the park and the surrounding community.

<span class="mw-page-title-main">Rocky Peak</span> Mountain in southern California, United States

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 2,715 feet (828 m) in elevation, sits on the Los Angeles County–Ventura County line.

<span class="mw-page-title-main">Upper Las Virgenes Canyon Open Space Preserve</span>

The Upper Las Virgenes Canyon Open Space Preserve is a large open space nature preserve owned and operated by the Santa Monica Mountains Conservancy spanning nearly 3,000 acres (1,200 ha) in the Simi Hills of western Los Angeles County and eastern Ventura County.

<span class="mw-page-title-main">Santa Monica Mountains National Recreation Area</span> Protected area in Southern California, US

The Santa Monica Mountains National Recreation Area is a United States national recreation area containing many individual parks and open space preserves, located primarily in the Santa Monica Mountains of Southern California. The SMMNRA is in the greater Los Angeles region, with two thirds of the parklands in northwest Los Angeles County, and the remaining third, including a Simi Hills extension, in southeastern Ventura County.

<span class="mw-page-title-main">Bell Canyon, California</span> Place in California, United States

Bell Canyon is an unincorporated community in eastern Ventura County, California, United States. Bell Canyon is a gated community in the Simi Hills with the main access through the Los Angeles community of West Hills and the western San Fernando Valley. Bell Canyon sits at an elevation of 1,368 feet (417 m). The 2020 census reported Bell Canyon's population was 1,946. For statistical purposes, the Census Bureau has defined Bell Canyon as a census-designated place (CDP). According to a 2016 study, Bell Canyon is the seventh wealthiest community in the state of California with an annual median income of $230,000.

<span class="mw-page-title-main">Simi Peak</span> Mountain in the American state of California

Simi Peak is the highest peak in the Simi Hills of Southern California, at 2,405 feet (733 m).

Bell Canyon Park is a large open-space regional park located in the Simi Hills at the western end of the San Fernando Valley in West Hills, Los Angeles and Bell Canyon, California. Bell Creek, a primary tributary to the Los Angeles River, flows through the park with riparian zone vegetation along its natural banks. The geographic landmark Escorpión Peak is high above it to the south in adjacent El Escorpión Park.

<span class="mw-page-title-main">Santa Susana Pass State Historic Park</span> State historic park in Los Angeles County, California, United States

Santa Susana Pass State Historic Park is a California State Park of 670.68 acres (2.7141 km2) located in the city of Los Angeles, in Los Angeles County on the boundary between Ventura and Los Angeles counties, between the communities of Chatsworth and Simi Valley. Geologically, the park is located where the Simi Hills meet the Santa Susana Mountains. Here in the western part of the Transverse Ranges, the land is dominated by high, narrow ridges and deep canyons covered with an abundant variety of plant life. The park offers panoramic views of the rugged natural landscape as a striking contrast to the developed communities nearby. The park is also rich in archaeological, historical, and cultural significance.

<span class="mw-page-title-main">Simi Valley, California</span> City in California, United States

Simi Valley is a city in the valley of the same name in the southeast region of Ventura County, California, United States. Simi Valley is 40 miles (65 km) from Downtown Los Angeles, making it part of the Greater Los Angeles Area. The city borders Thousand Oaks, Moorpark, and the Chatsworth neighborhood of Los Angeles. As of the 2020 U.S. Census the population was 126,356, up from 124,243 in 2010. The city of Simi Valley is surrounded by the Santa Susana Mountains and the Simi Hills, west of the San Fernando Valley, and northeast of the Conejo Valley. It grew as a bedroom community for the cities in the Los Angeles area and the San Fernando Valley when a freeway was built over the Santa Susana Pass.

<span class="mw-page-title-main">Bell Creek (Southern California)</span> River in the United States

Bell Creek is a 10-mile-long (16 km) tributary of the Los Angeles River, in the Simi Hills of Ventura County and the San Fernando Valley of Los Angeles County and City, in Southern California.

<span class="mw-page-title-main">Santa Susana, California</span> Place in California, United States

Santa Susana is a former railroad town located mostly within the City of Simi Valley. A small portion of the community, outside the Simi Valley city limits to the south of the Ventura County Metrolink rail line, is an unincorporated area and census-designated place (CDP). The community is in the eastern part of the Simi Valley.

China Flat is a plateau in the north−central Simi Hills, in Ventura County, Southern California.

<span class="mw-page-title-main">Sage Ranch Park</span> Public park and nature preserve in Ventura County, California

Sage Ranch Park is a 625-acre park (253 ha) and wildlife corridor located at a 2,000 feet (610 m) height in the northwestern Simi Hills on the northwestern plateau of the Simi Valley, bordering Los Angeles County and its San Fernando Valley. The campground area used to be a cattle ranch and later a filmset for Western movies. Sage Ranch Park is today an intermountain wildlife corridor, which links the Simi Hills with the Santa Susana- and Santa Monica Mountains. The mountainous park is mostly known for its unique sandstone rock formations, maybe particularly on its western side where the Sandstone Ridge and Turtle Rock are situated. On its northern side, there are great panoramic rural and metropolitan views of the Simi Valley, as well as surrounding Simi Hills, Santa Susana Mountains and beyond. It is home to numerous sandstone formations, caves, outcroppings, tilted rock formations, several hiking trails, a camping ground, as well as native flora and wildlife. The area is lined with coastal sage scrub and other flora includes chaparral, bush lupine, California poppy, sunflowers, Cream Cups, bracken, sword fern, prickly pear cactus, eucalyptus trees, oak woodland of ceanothus, coffee berry, California buckwheat, sycamore, Walnut Tree, ferns, orange- and avocado trees. It is a critical cross-mountain wildlife corridor and is home to fauna such as mountain lions, bobcats, eagles, vultures, owls, rattle snakes, coyotes, hawks, grey fox, king snakes, and more. Bordering Sage Ranch to the south is the Rocketdyne Santa Susana Field Laboratory, in which the nearby Burro Flats Painted Cave is located.

<span class="mw-page-title-main">Arroyo Conejo</span> Creek in the Conejo Valley, California

Arroyo Conejo carries part of the longest creek in the Conejo Valley which sprawls past the cities of Thousand Oaks and Camarillo, and the communities of Newbury Park, Casa Conejo and Santa Rosa Valley. Arroyo Conejo is the primary drainage for the City of Thousand Oaks. Its watershed covers 57 square miles (150 km2) of which 43 square miles (110 km2) are in the Conejo Valley and 14 square miles (36 km2) in the Santa Rosa Valley.

References

  1. ↑ "Simi Hills". Geographic Names Information System . United States Geological Survey, United States Department of the Interior . Retrieved 2009-05-03.
  2. ↑ Cilona, Antonino; Aydin, Atilla; Johnson, Nicholas M. (March 2015). "Permeability of a fault zone crosscutting a sequence of sandstones and shales and its influence on hydraulic head distribution in the Chatsworth Formation, California, USA". Hydrogeology Journal. 23 (2): 406. Bibcode:2015HydJ...23..405C. doi: 10.1007/s10040-014-1206-1 . S2CID   129607293.
  3. ↑ "Simi Peak". Geographic Names Information System . United States Geological Survey, United States Department of the Interior . Retrieved 2009-05-03.
  4. ↑ "Chatsworth Peak". Geographic Names Information System . United States Geological Survey, United States Department of the Interior . Retrieved 2009-05-03.
  5. ↑ Myers, Amanda Lee (June 19, 2018). "4 new mountain lion kittens found in California mountains". The Associated Press . Retrieved 21 June 2018.
  6. ↑ Roth, Annie (June 21, 2018). "Den of Mountain Lion Kittens Found in Unlikely Place". National Geographic . Archived from the original on June 22, 2018. Retrieved 21 June 2018.
  7. ↑ PD-icon.svg This article incorporates public domain material from California Red-Legged Frogs: Santa Monica Mountains National Recreation Area. National Park Service . Retrieved 2021-07-12.
  8. ↑ USA Today article USA Today Accessed 2/22/2008
  9. ↑ "Mercury News article". mercurynews.com. Retrieved 9 April 2018.
  10. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2010-03-14. Retrieved 2010-03-23.{{cite web}}: CS1 maint: archived copy as title (link) SSPSHP Ethnohistory Accessed 2/28/2010
  11. ↑ " "Wishtoyo - Projects - Cultural - Ahmanson Ranch". Archived from the original on 2009-03-13. Retrieved 2010-03-24. Ahmanson Ranch Becomes Private Preserve," [Wishtoyo Foundation website. Accessed 10/23/2007
  12. ↑ Wishtoyo on Ahmanson Ranch accessed 10-23-2007 Archived 2009-03-13 at the Wayback Machine
  13. ↑ http://www.nps.gov/juba/ National Park Service: official Juan Bautista de Anza National Historic Trail website. accessed 4/06/2010
  14. ↑ http://www.dtsc-ssfl.com/default.asp?V_DOC_ID=959 State DTSC-SSFL_Area IV Nuclear Research section. accessed 4/06/2010
  15. ↑ http://www.dtsc-ssfl.com/default.asp?V_DOC_ID=942 State DTSC-SSFL Groundwater Interactive Database. accessed 4/06/2010
  16. ↑ Rim of the Valley Trail Corridor
  17. ↑ http://smmc.ca.gov/ROV%20Master%20Plan.pdf access date: 6/6/2010
  18. ↑ http://www.glendalenewspress.com/news/gnp-valley060510,0,1520788.story access date: 6/6/2010
  19. ↑ http://www.modernhiker.com/2010/06/03/rim-of-the-valley-corridor-study-begins/comment-page-1/ access date: 6/6/2010
  20. ↑ Kamal, Sameea (March 4, 2015). "Three lawmakers urge Park Service action on Rim of the Valley study". Los Angeles Times.
  21. ↑ http://www.recreationparks.net/CA/los-angeles/bell-canyon-park-los-angeles Bell Canyon Park. accessed 11/22/2009.
  22. ↑ http://www.nps.gov/samo/planyourvisit/cheeseboropalocomado.htm Cheeseboro/Palo Comado Canyon Park. accessed 6/6/2010.
  23. ↑ http://www.lamountains.com/parks.asp?parkid=83 Cheeseboro Park. accessed 11/22/2009.
  24. ↑ Cheeseboro/Palo Comado Canyon Park
  25. ↑ http://www.recreationparks.net/CA/los-angeles/el-escorpion-park-los-angeles El Escorpión Park. accessed 11/22/2009.
  26. ↑ http://venturacountytrails.org/RecentPhotos/2010-02-13CastlePeak/_Page.html venturacountytrails.org-Escorpion Peak. accessed 4/04/2010
  27. ↑ http://www.lamountains.com/parks.asp?parkid=51 www.lamountains. Rocky Peak Park. access date: 6/6/2010
  28. ↑ http://www.lamountains.com/parks.asp?parkid=53 SMMC-Sage Ranch Park Info. accessed 6/6/2010
  29. ↑ http://www.lamountains.com/maps/sageRanch.pdf SMMC-Sage Ranch Park Map. accessed 2/28/2010
  30. ↑ "Parks - LAMountains.com". www.lamountains.com. Retrieved 9 April 2018.
  31. ↑ http://www.parks.ca.gov/default.asp?page_id=611 official Santa Susana Pass State Historic Park website. accessed 1/25/2010.
  32. ↑ http://www.lamountains.com/parks.asp?parkid=123 Archived 2010-02-07 at the Wayback Machine Santa Susana Pass State Historic Park info. accessed 11/22/2009.
  33. ↑ "Parks - LAMountains.com". www.lamountains.com. Retrieved 9 April 2018.
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