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Earth of fire

Actualité volcanique, Article de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié par Bernard Duyck
Publié dans : #Excursions et voyages

The Jarvis Island, close to the new seamount discovered in August 2014 / link, is part of the Line islands, also called equatorial Sporades, a chain of seamounts, atolls and volcanic islands extending over 4,800 km in the central Pacific basin and surrounded by seabed over 5,000 meters.
Only twelve underwater volcanoes reach the level of the sea to form low islands and atolls, now lined with narrow fringing reefs extending only 1.5 km. maximum.

Some seamounts form atolls with lagoons with a pass opening to the ocean, like Fanning, Palmyra and Caroline Islands. Others form low and flat islands, like Jarvis, Vostok, Flint ... the Christmas and Johnston Islands, the highest, have only dunes up to 12 m.

Jarvis Island - the coral island and its fringing reef - note the shallow ocean shelf on the right - photo Nasa 2005

Jarvis Island - the coral island and its fringing reef - note the shallow ocean shelf on the right - photo Nasa 2005

Position of the Line islands among the Pacific island chains. - Doc. Tulane University

Position of the Line islands among the Pacific island chains. - Doc. Tulane University

The Line Islands are part of United States Minor Outlying Islands, and the Kiribati group. Geographically, they are divided into Northern, Central and Southern Line Islands.

On ten islands and atolls, only three are currently inhabited: Christmas, Tabueran and Teraina, for a total of about 9,000 inhabitants.

Maps of Jarvis island - a clic to enlarge.Maps of Jarvis island - a clic to enlarge.

Maps of Jarvis island - a clic to enlarge.

Jarvis island - bathymétrie multibeam 3D - doc.PIBHMC / Hawaii Manoa University..

Jarvis island - bathymétrie multibeam 3D - doc.PIBHMC / Hawaii Manoa University..

Unlike most of the atolls, only exposed at low tide, Jarvis Island has a "dry" reef platform , where large deposits of guano are accumulated.

This coral island has an area of 4.5 km ², and its highest eight meters above water level issue.

The soil consists mainly of coral sand, and is home to only rare grasses and low shrubs. The outside edges of fringing reefs are bordered by steep slopes, except on the East Coast, where a shallow plateau (less than 20 meters) extends from 500 to 1000 meters. The habitat is favorable for wildlife and seabirds. The island has no fresh water point, or port.

Jarvis sign prohibiting the enter - Jarvis island Wildlife refuge.

Jarvis sign prohibiting the enter - Jarvis island Wildlife refuge.

Jarvis island - above: Coral / Jarvis Island National Wildlife Refuge - Photo credit USFWS, Jim Maragos - - below: Porites colony, massive and fingered corals, biobuilders, involved in the construction of reefs. (in the insert, rings of growtj) - doc.http: //www.lgt.lt
Jarvis island - above: Coral / Jarvis Island National Wildlife Refuge - Photo credit USFWS, Jim Maragos - - below: Porites colony, massive and fingered corals, biobuilders, involved in the construction of reefs. (in the insert, rings of growtj) - doc.http: //www.lgt.lt

Jarvis island - above: Coral / Jarvis Island National Wildlife Refuge - Photo credit USFWS, Jim Maragos - - below: Porites colony, massive and fingered corals, biobuilders, involved in the construction of reefs. (in the insert, rings of growtj) - doc.http: //www.lgt.lt

Discovered in 1821 by Captain Brown, commander of the ship Eliza Francis, owned by the Jarvis family, it was proclaimed in 1856 by the United States in the Guano Act, a federal law that allows American citizens to take possession of the uninhabited and unclaimed guano islands... but giving no obligation once the operation stopped. The guano deposits were mined from 1857 to 1879. Annexed by the British in 1889, it was claimed in 1935 by the United States. It is not permanently inhabited, and the few settlers were evacuated during the second world war. The only remnants of the occupation are a small lighthouse and the remains of the  Guano tramway. In 1974, Jarvis Island National Wildlife Refuge, including 5.15 square kilometers of land and 1,734 square kilometers of marine area, was created and integrated in 2009 in the Pacific Remote Islands Marine National Monument.

Jarvis Island: left , the lighthouse on the west coast / Joann94024 - right photo: remains of the Guano tramwayJarvis Island: left , the lighthouse on the west coast / Joann94024 - right photo: remains of the Guano tramway

Jarvis Island: left , the lighthouse on the west coast / Joann94024 - right photo: remains of the Guano tramway

White tern / Jarvis island

White tern / Jarvis island

Jarvis is home to 14 species of breeding seabirds including boobies, masked,brown or red-footed, frigates, brown and blue noddies, shearwaters, tropicbirds of  whiteTern ... not to mention the small waders, curlews, plovers and turnstones. Its colony of sooty terns is one of the largest in the world, with one million people.

 

Sources:

- Geology and geochronology of the line islands - Schlanger - 2012 - Journal of Geophysical Research  Solid Earth (1978–2012) -

- Center for coastal and ocean mapping / Joint Hydrographic center – Line islands - link

- Pacific Remote Island Area (PRIA) - link

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