Farallon Islands, with border of Farallon Islands National Wildlife Refuge

Southeast Farallon Islands (from nautical chart of 1957)

View of research station at Marine Terrace, with Farallon Island Light above

Geology

The Farallon Islands are outcroppings of the Salinian Block, a vast geologic province of granitic continental crust sharing its origins with the core of the Sierra Nevada Mountains. The block was torn off far to the south and rifted north by the San Andreas Fault which lies to the east of the islands. Other nearby examples of the Salinian Block include the Point Reyes Peninsula and Bodega Head.

Geography

Overview

The islands string north westwards for 8 km. Their total land area is 0.42 km². The Territorial waters measure 247.5 km². The islands were initially exploited for bird eggs and fur seal skins, then used as a lighthouse station and a radio station. They have been protected in the Farallon National Wildlife and Wilderness Refuge, established in 1969, and contain the largest seabird colony in the U.S. outside of Alaska and Hawaii. The islands are part of the City and County of San Francisco, and are considered part of Supervisorial District One (Northwest), also called Richmond District.

South Farallon Islands

• Southeast Farallon Island (SEFI) is the largest island, with an area of 0.31 km² or 310,406 m²) and is the only inhabited one. The island is pyramidal in shape and 109 meters high. The peak, Tower Hill (actually a double peak consisting of Lighthouse Hill and Little Lighthouse Hill), is the location of a lighthouse, the Farallon Island Light. The large flat area in the southeast of the island is called Marine Terrace. Immediately south of it is Mussel Flat, about 30 by 120 meters, which is cut off from the main island only during high tide.
• Seal Rock (Saddle Rock), about 250 meters south of SEFI is, about 80 by 250 meters in size, and 25 meters high.
• Maintop Island (West End) is immediately to the west of SEFI, separated by a narrow impassable gorge, The Jordan (Jordan Channel), which connects Mirounga Bay in the south to Maintop Bay in the north. It is the second largest island, and 68 meters high at Main Top hill in its eastern part. The Great West Arch, a rock formation, is in the west of the island, and Indian Head in the South.

Aulon Island, Great Arch Rock and Sugarloaf, as seen from SEFI.

• The Drunk Uncle Islets are a group of small rocks just northwest off Maintop Island.
• Aulone Island and smaller Great Arch Rock (Arch Rock) are immediately north of the northern tip of SEFI, and together about 60 by 120 meters in size. They are barely separated by a narrow gorge. Great Arch Rock is not to be confused with Great West Arch, a rock formation in the west of Maintop Island.
• Sugarloaf Island (usually just referred to as Sugarloaf) is northeast of Great Arch Rock, and just slightly larger in size, with a height of 25 meters. Southwest of Aulon Island, Great Arch Rock and Sugarloaf Island, and in the northeast of SEFI, is protected Fisherman Bay.
• Sea Lion Rock is just northwest of Aulon Island, diameter approximately 40 meters.
• Hurst Shoal is located about one kilometer southeast of the southeastern corner of SEFI. It has a least depth of 6.2 meters.

Farallon Islands and banks further northwest

Middle Farallon Island

Middle Farallon Island, 3 km northwest of SEFI, is a 6 meters high guano-covered black rock about 65 meters in diameter, with an area of 3,362 m². This island is informally known as "the pimple."

North Farallon Islands

North Farallon Islands, about 7 km further northwest, consist of two clusters of bare precipitous islets and rocks 28 to 1,200 meters high, with an aggregate area of 28,270 m²

• North Farallon Island, 31 meters high, about 150 meters long north-south, 9,260 m²
• Island of St. James, 350 meters high, about 125 meters in diameter, 12,380 m²
• unnamed rock, about 85 meters in diameter, and 5,640 m² in area
• four smaller unnamed rocks, diameter 20 meters and less

Some of those unnamed rocks however have Spanish names, such as Piedra Guadalupe, Peñasco Quebrado and Farallón Vizcaíno.

Fanny Shoal

5 km WNW of the North Farallones is Fanny Shoal, a bank 3 km in extent, with depth less than 55 meters, marking the northernmost and westernmost feature of the group, albeit entirely submerged. Noonday Rock, at 5 km WNW of the North Farallones the northernmost and westernmost feature of the group, is submerged, rising abruptly from a depth of 37 meters, with a least depth of 4 meters (13 feet) over it at low tide, is the shallowest point of Fanny Shoal. There is a lighted bell buoy about 1 km west of Noonday Rock. Noonday Rock derives its name from the clipper ship that struck it on January 1 1863 and sank within one hour.^[1]

Banks northwest of Fanny Shoal

The banks northwest of Fanny Shoal are not considered part of the Farallon Islands anymore, and they are outside of U.S. territorial waters. About 25 km northwest of Fanny Shoal is Cordell Bank, a significant marine habitat (). About halfway between Fanny Shoal and Cordell Bank is Rittenburg Bank, with depths of less than 80 meters ().

History

Image of the San Francisco Bay area, showing relative position of the Farallones

In the years following their discovery, the islands were exploited by seal hunters, first from New England and later from Russia. The Russians maintained a sealing station in the Farallones from 1819 to 1838, decimating the islands' population of fur seals (it is not known whether the Northern Fur Seal or the Guadalupe Fur Seal were the islands' native fur seal, although the Northern Fur Seal is the species that has recolonized the islands after they became protected) (White, 1995).

Southeast Farallon Islands from the west,
with Maintop Island in the foreground (right)

The islands are the site of many shipwrecks, including the liberty ship SS Henry Bergh, a converted troop carrier that hit West End in 1944, pieces of which can still be seen from the island today (all hands were saved). The United States Coast Guard maintained a manned lighthouse until 1972, when it was automated. The islands are currently managed by the United States Fish and Wildlife Service, in conjunction with the Marin-based PRBO Conservation Science (formerly Point Reyes Bird Observatory - PRBO). The islands are currently the subject of long term ecological research. Today, the Farallones are closed to the public, although birders and wildlife enthusiasts can approach them on whale watching boats.

For about eleven years, from 1902 to 1913, the former U.S. Weather Bureau maintained a weather station on the southeast island; a cable connected the station with the mainland. The results of the meteorology study were later published in a book on the California climate. Temperatures during those years never exceeded 90°F or dropped to 32°F.^[2] Years later, the National Weather Service provided some weather observations from the lighthouse on its local radio station.

Nuclear waste

In the above map the approximate locations of two major nuclear waste dumping sites, according to a 1980 EPA report, are indicated.

Wildlife

Common Murre colony on the Farallones.

Seabirds

The Farallon Islands are an important reserve protecting a huge seabird colony. The islands' position in the highly productive California Current and Eastern Pacific upwelling region, as well as the absence of other large islands that would provide suitable nesting grounds, result in a seabird population of over 250,000. Twelve species of seabird and shorebird nest on the islands; Western Gull, Brandt's Cormorant, Pelagic Cormorant, Double-crested Cormorant, Pigeon Guillemot, Common Murre, Cassin's Auklet, Tufted Puffin, Black Oystercatcher, Rhinoceros Auklet, Ashy Storm-petrel, and Leach's Storm-petrel. Since the islands were protected, Common Murres, which once numbered nearly 500,000 pairs but suffered from the egg collecting, oil spills and other disturbances which had greatly reduced their numbers, recovered and climbed from 6,000 birds to 160,000. Additionally, since protection, the locally extinct Rhinoceros Auklet has begun to breed on the islands again. The island has the world's largest colonies of Western Gulls and Ashy Storm-petrels, the latter species being considered endangered and a conservation priority. The island also is the wintering ground of several species of migrants, and regularly attracts vagrant birds (about 400 species of bird have been recorded on or around the island).

Seals

Five species of pinniped come to shore on the islands, and in some cases breed. These are the Northern Elephant Seal, Harbor Seal, Steller's Sea Lion, California Sea Lion, and the Northern Fur Seal (the last of which, like the Rhinoceros Auklet, began to return to the island again after protection).

Whales

Several species of cetaceans are found near the Farallon Islands, most frequently Gray whales, Blue whales, and Humpback whales. Blue whales and Humpback whales are most frequently found near the islands in the summer and fall, when strong upwelling may support a rich pelagic food web. Grey whales are reliably found near the Farallones during their spring migration north and the fall/winter migration south. Some Grey whales may also be found during the summer, when a few whales skip the trip north to Alaska and spend the summer months off the coast of Canada and the continental U.S.

In December 2005 one Humpback was rescued from netting entanglement east of the Farallons by staff of The Marine Mammal Center. The last sighting of another famous humpback, named Humphrey, was near the Farallones in 1991. The islands are in the Gulf of the Farallones National Marine Sanctuary, which protects the feeding grounds of the wildlife of the refuge.

Sharks

The elephant seal population attracts a population of well-known Great White Sharks to the islands. In 1970 Farallon biologists witnessed their first shark attack, on a Steller?s sea lion. During the next fifteen years, more than one hundred attacks on seals and sea lions were observed at close range. By the year 2000, biologists were logging almost eighty attacks in a single season. No one had ever documented such behavior among great whites before.

While the males return annually, the females return only every other year, often with fresh, deep bites around their heads. The seasonal population at the Farallones is a wild guess: anywhere from thirty to one hundred. The Farallones are unique in the size of the Great Whites that are attracted. The average length of a full-grown great white shark is 4 to 4.8 metres (13.3 to 15.8 ft), with a weight of 680 to 1,100 kilograms (1,500 to 2,450 lbs), females generally being larger than males. Farallon Great Whites range between the "smaller" males at 13 ft. to the females which generally range between 17-19 ft. (The largest accurately measured great white shark was a female caught in August 1988 at Prince Edward Island off the North Atlantic coast and measured 20.3 ft).

Some individual sharks have been tagged and found to roam the Pacific as far as Hawaii, returning regularly to the Farallones every year in the autumn. ^[8] Orcas have been seen attacking the sharks.

See also

• Islands of San Francisco Bay
• San Francisco Bay Area

References

• White, Peter; (1995), The Farallon Islands: Sentinels of the Golden Gate, San Francisco: Scottwall Associates, ISBN 0-942087-10-0
• Casey, Susan; (2005), The Devils Teeth: A True Story of Obsession and Survival Among America's Great White Sharks, New York: Henry Holt and Co., ISBN 0-8050-7581-X

Notes

1. ↑
2. ↑ U.S. Fish & Wildlife Service
3. ↑ U.S. Environmental Protection Agency, Radioactive Waste Dumping Off the Coast of California, Fact Sheet (14 August 1980).
4. ↑ Hunters Point Shipyard Historical Radiological Assessment (August 2004), p. 6-30. Warning: PDF file is 47.9 MB in size.
5. ↑ HPS Historical Radiological Assessment, p. 6-24.
6. ↑ USGS, Farallon Island Radioactive Waste Dump.
7. ↑ EPA, "Radioactive Waste Dumping Off the Coast of California, Fact Sheet", p. 6.
8. ↑ Devil's Teeth, Holt, 2005, p.171

External links

• Farallon Islands National Wildlife Refuge USFWS
• Farallon Islands San Francisco Chronicle article.
• Farallon Islands at the Center for Land use Interpretation
• Article about nuclear waste at the Farallons
• farallones.org
• Area figures from [[Bureau of the Census]]
• The Farallon Blog Weblog of the field biologists on the Farallon Islands

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