Point Bonita Light
Encyclopedia
Point Bonita Light is a lighthouse
located at Point Bonita at the San Francisco Bay
entrance in the Marin Headlands
near Sausalito, California
. Point Bonita was the last manned lighthouse on the California coast.
has dense high fog
, which leaves lower elevations clear. The original light was 306 feet (93.3 m) above sea level so the second order Fresnel lens
was often cloaked in fog
and could not be seen from the sea. In 1877, the lighthouse was moved to its current location at 124 feet (37.8 m) above sea level. The United States Coast Guard
currently maintains the light and fog signal. It is accessible to the public during limited hours (12:30 PM–3:30 PM) on Saturdays, Sundays, and Mondays. Up until 1940 the lighthouse could be reached without a bridge, but erosion
caused a trail leading to the lighthouse to crumble into the sea. A wooden walkway was installed, but when that became treacherous the suspension bridge was built in 1954. The bridge was intended to mirror the design of the nearby Golden Gate Bridge
.
As of January 6, 2010, the suspension bridge
to the light house has been closed to public access. According to the Federal Highway Administration
, the bridge, which is 56 years, has started to rust
. It underwent repairs in 1979 and again in 1991, but the metal components are not able to stand up to the sea spray
. The new span is set to open in March 2012. The new bridge construction is expected to cost between $850,000 and $1.3 million. The bridge will be made from tropical hardwood
and steel suspension cables and attachments.
Historical Information from USCG web site:
More than 300 boats ran aground near the Golden Gate during the Gold Rush years. One shipwreck
, the SS City of Rio de Janeiro
, is just a few hundred feet offshore from the light.
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....
located at Point Bonita at the San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
entrance in the Marin Headlands
Marin Headlands
The Marin Headlands is a hilly area at the southernmost end of Marin County, California, just north of the Golden Gate Bridge. The Headlands are located just north of San Francisco, immediately across the Golden Gate Bridge. The entire area is part of the Golden Gate National Recreation Area...
near Sausalito, California
Sausalito, California
Sausalito is a San Francisco Bay Area city, in Marin County, California, United States. Sausalito is south-southeast of San Rafael, at an elevation of 13 feet . The population was 7,061 as of the 2010 census. The community is situated near the northern end of the Golden Gate Bridge, and prior to...
. Point Bonita was the last manned lighthouse on the California coast.
History
The original Point Bonita Lighthouse, a 56 feet (17.1 m) brick tower, was located too high. Unlike the East Coast of the United States, the West CoastWest Coast of the United States
West Coast or Pacific Coast are terms for the westernmost coastal states of the United States. The term most often refers to the states of California, Oregon, and Washington. Although not part of the contiguous United States, Alaska and Hawaii do border the Pacific Ocean but can't be included in...
has dense high fog
Fog
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...
, which leaves lower elevations clear. The original light was 306 feet (93.3 m) above sea level so the second order Fresnel lens
Fresnel lens
A Fresnel lens is a type of lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses.The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design...
was often cloaked in fog
Fog
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...
and could not be seen from the sea. In 1877, the lighthouse was moved to its current location at 124 feet (37.8 m) above sea level. The United States Coast Guard
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...
currently maintains the light and fog signal. It is accessible to the public during limited hours (12:30 PM–3:30 PM) on Saturdays, Sundays, and Mondays. Up until 1940 the lighthouse could be reached without a bridge, but erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
caused a trail leading to the lighthouse to crumble into the sea. A wooden walkway was installed, but when that became treacherous the suspension bridge was built in 1954. The bridge was intended to mirror the design of the nearby Golden Gate Bridge
Golden Gate Bridge
The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening of the San Francisco Bay into the Pacific Ocean. As part of both U.S. Route 101 and California State Route 1, the structure links the city of San Francisco, on the northern tip of the San Francisco Peninsula, to...
.
As of January 6, 2010, the suspension bridge
Suspension bridge
A suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. Outside Tibet and Bhutan, where the first examples of this type of bridge were built in the 15th century, this type of bridge dates from the early 19th century...
to the light house has been closed to public access. According to the Federal Highway Administration
Federal Highway Administration
The Federal Highway Administration is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two "programs," the Federal-aid Highway Program and the Federal Lands Highway Program...
, the bridge, which is 56 years, has started to rust
Rust
Rust is a general term for a series of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture...
. It underwent repairs in 1979 and again in 1991, but the metal components are not able to stand up to the sea spray
Sea spray
Sea spray is a spray of water that forms when ocean waves crash.-Make up:As a result, salt spray contains a high concentration of mineral salts, particularly chloride anions.-Effects:...
. The new span is set to open in March 2012. The new bridge construction is expected to cost between $850,000 and $1.3 million. The bridge will be made from tropical hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
and steel suspension cables and attachments.
Historical Information from USCG web site:
- Point Bonita Light Station had the first fog signal on the West Coast. It was an Army surplus 24-pounder siege gun.
- This light is the only one in America that can be reached only by crossing a suspension bridge.
- In 1877 the lighthouse was moved to its current location because the original location was often too obscured by fog for the light to be visible from the bay. This location required the builders to overcome many challenges, including the need for a hand carved, 118 feet (36 m) long hard rock tunnel.
More than 300 boats ran aground near the Golden Gate during the Gold Rush years. One shipwreck
Shipwreck
A shipwreck is what remains of a ship that has wrecked, either sunk or beached. Whatever the cause, a sunken ship or a wrecked ship is a physical example of the event: this explains why the two concepts are often overlapping in English....
, the SS City of Rio de Janeiro
SS City of Rio De Janeiro
The SS City of Rio de Janeiro was an iron hulled steam powered passenger ship, launched in 1878, which sailed between San Francisco and various Asian Pacific ports. On 21 February 1901, the vessel sank after striking a submerged reef at the entry to San Francisco Bay while inward bound from Hong...
, is just a few hundred feet offshore from the light.