Devil's Slide is a coastal

promontory A promontory is a raised mass of land that projects into a lowland or a body of water (in which case it is a peninsula). Most promontories either are formed from a hard ridge of rock that has resisted the erosive forces that have removed the so ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, United States. It lies on the

San Mateo County San Mateo County ( ), officially the County of San Mateo, is a county located in the U.S. state of California. As of the 2020 census, the population was 764,442. Redwood City is the county seat, and the third most populated city following Daly ...

coast between Pacifica and Montara. Its name comes from the rocky edges prone to accident.

Natural setting

Devil's Slide is a name given to a steep, rocky coastal

located about midway between Montara and the Linda Mar District of Pacifica. The terrain is characterized by steep, eroded slopes with natural gradients ranging between 30 and 50%. There are small coastal valleys throughout along the major drainages within the

Montara Mountain Montara Mountain, positioned between the unincorporated community of Montara, California, to the southwest and the city of Pacifica, California, to the north, forms the northern spur of the Santa Cruz Mountains, a narrow mountain range running the ...

watershed. The soils in these valleys are deep and moderately well-drained and have developed along the low terraces and alluvial fans of the stream channels. The climate of the area is

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

with a strong maritime influence. The temperature range is narrow both seasonally and diurnally, while air moisture is relatively high. Extremely dense

northern coastal scrub Northern coastal scrub is a scrubland plant community of California and Oregon. It occurs along the Pacific Coast from Point Sur on the Central California coast in Monterey County, California, to southern Oregon. It frequently forms a landscape mo ...

covers most of the locale, especially over San Pedro Mountain and along the steeper foot slopes of Montara Mountain. Small grassy openings and barren rocky areas are scattered throughout the scrub areas. The inland area holds other types of vegetation including aquatic and coastal freshwater marshes/seeps, willow riparian scrub, coastal grassland, non-native forest, and pasture/ranch uses/non-native brushland. The

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

Hickman's potentilla ''Potentilla hickmanii'' (called Hickman's potentilla or Hickman's cinquefoil) is an endangered perennial herb of the rose family. This rare plant species is found in a narrowly restricted range in two locations in coastal northern California, ...

occurs on the slopes above

Martini Creek Martini Creek is a coastal stream whose watershed lies entirely within San Mateo County, California, United States on the western exposures of the Montara mountain block, discharging to the Pacific Ocean. It flows about from its source on Montara ...

at up to elevation.

Former State Route 1

Immediately east of Devil's Slide is a former stretch of

California State Route 1 State Route 1 (SR 1) is a major north–south state highway that runs along most of the Pacific coastline of the U.S. state of California. At , it is the longest state route in California, and the second-longest in the US after Monta ...

, famous for closures and

landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

s, which also was called "Devil's Slide". Construction of the road began in 1935 and was completed in 1936, replacing the steep, narrow, and winding

Pedro Mountain Road Pedro Mountain Road describes a series of historical road crossings of Pedro Mountain, a promontory ridge located between Montara Mountain and the coastal cliffs of Devil's Slide in San Mateo County, California. This Pedro Mountain headland block ...

. It was known for landslides and

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

that often occur during winter storms, sometimes making the road impassable. Devil's Slide was originally part of

Ocean Shore Railroad The Ocean Shore Railroad was a railroad built between San Francisco and Tunitas Glen, and Swanton and Santa Cruz that operated along the Pacific coastline from 1905 until 1921. The route was originally conceived to be a continuous line betwee ...

that was proposed between San Francisco to Santa Cruz. The first major landslide destroyed much of the road in 1940. Another large slide in 1995 forced the road's closure for almost two years. In April 2006, the road began to develop large longitudinal cracks in the roadbed, indicating an imminent slide and forcing the highway's closure for five months as

CalTrans The California Department of Transportation (Caltrans) is an Executive (government), executive department of the U.S. state of California. The department is part of the Government of California#State agencies, cabinet-level California State Tran ...

worked to stabilize the slide. On March 25, 2013, Caltrans shut down the landslide-prone coastal road, replacing it with the

Tom Lantos Tunnels The Tom Lantos Tunnels are two tunnels located within the coastal promontory of Montara Mountain, on the San Francisco Peninsula in California, United States, created to allow rerouting California State Route 1, State Route 1 to avoid a portion of ...

, which take the highway through the promontory behind the precarious cliffs. On , the -long Devil's Slide Trail was opened to pedestrians and bicyclists, taking over the section of roadway formerly used by State Route 1 and now bypassed by the new tunnels. The total cost to convert the highway into a trail was .

In popular culture

Devil's Slide was used in a key scene of the 1960 thriller ''

Portrait in Black ''Portrait in Black'' is a 1960 American neo-noir melodrama film directed by Michael Gordon, and starring Lana Turner and Anthony Quinn. Produced by Ross Hunter, the film was based on the play of the same by name by Ivan Goff and Ben Roberts, w ...

'' with

Lana Turner Lana Turner ( ; born Julia Jean Turner; February 8, 1921June 29, 1995) was an American actress. Over the course of her nearly 50-year career, she achieved fame as both a pin-up model and a film actress, as well as for her highly publicized per ...

and

Anthony Quinn Manuel Antonio Rodolfo Quinn Oaxaca (April 21, 1915 – June 3, 2001), known professionally as Anthony Quinn, was a Mexican-American actor. He was known for his portrayal of earthy, passionate characters "marked by a brutal and elemental v ...

. Turner and Quinn portrayed doomed lovers who deliberately pushed a car, containing the body of a murdered man, over the edge of the cliff. The

Universal Universal is the adjective for universe. Universal may also refer to: Companies * NBCUniversal, a media and entertainment company ** Universal Animation Studios, an American Animation studio, and a subsidiary of NBCUniversal ** Universal TV, a t ...

crew obtained permission from the State of California to stage the scene, which involved retrieving the car from the bottom of the cliff once the scene had been successfully filmed. The ''San Mateo Times'' printed a photograph of the filming of this sequence.

Military history

Devil's Slide was the location of a military triangulation station and observation site used during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

as part of the harbor defense of

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

. Prior to the advent of radar, military personnel used binoculars and compasses to search for ships at sea and relay their coordinates to a central post. By combining information from multiple observation posts, a ship's precise location could be determined by

triangulation In trigonometry and geometry, triangulation is the process of determining the location of a point by forming triangles to the point from known points. Applications In surveying Specifically in surveying, triangulation involves only angle me ...

. There were six military structures at the Devil's Slide: three concrete and steel observation pill-boxes, two concrete-and-earth bunkers, and a reinforced steel observation tower. The pill-boxes were used as hardened observation posts, and one of the bunkers was used as a communications and command post. The southernmost bunker site was sold to a private owner in 1983, but some of the exposed structure remains.

Bibliography

* ''Biological Assessment, Species of Concern, Proposed Route 1 Devil's Slide Tunnel Bypass Project, San Mateo County, California'' Prepared by Caltrans, Office of Environmental Planning, South. July, 1998. * Michael Hogan and Ballard George, ''Air Quality and Noise Analyses for the Bypass Alternative, Devil's Slide Improvement Project'', Caltrans District 4, prepared by Earth Metrics Inc., Burlingame, CA (1984) * ''Devil's Slide Improvement Project, San Mateo County, California, Draft Second Supplemental Environmental Impact Statement'', Caltrans District 4 (1999) * Hovland, John H., Ph.D., P.E., ''A Study of the Feasibility of Stabilizing the Landslide Area Along Highway One, San Mateo County, California, by Dewatering'', April, 1998 * Woodward-Clyde Consultants, ''Devil’s Slide Tunnel Study - Feasibility Report'', October, 1996.

Footnotes

External links

California Coastal Commission

KQED QUEST photo montage and article on tunnel
{{coord, 37.574383, N, 122.520255, W, source:gnis-222326_region:US-CA_type:landmark, display=title Buildings and structures in San Mateo County, California Landforms of San Mateo County, California Roads in San Mateo County, California Coastal erosion in the United States California State Route 1 Landslides in the United States