Gardner Pinnacles
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The Gardner Pinnacles () are two barren rock outcrops surrounded by a reef and located in the Northwestern Hawaiian Islands. The Pūhāhonu volcano responsible for the pinnacles is northwest of
Honolulu Honolulu ( ; ) is the List of capitals in the United States, capital and most populous city of the U.S. state of Hawaii, located in the Pacific Ocean. It is the county seat of the Consolidated city-county, consolidated City and County of Honol ...
and from
French Frigate Shoals The French Frigate Shoals (Hawaiian language, Hawaiian: Kānemilohai) is the largest atoll in the Northwestern Hawaiian Islands, located about northwest of Honolulu, Hawaii, Honolulu. Its name commemorates France, French explorer Jean-Fran ...
. The total area of the two small islets, remnants of an ancient
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
, the world's largest, is . The highest peak is . The surrounding reef has an area in excess of .Gardner Pinnacles - Hawaiian Islands National Wildlife Refuge
U.S Fish and Wildlife Service. December 14, 2016
The Gardner Pinnacles were discovered and named in 1820 by the whaling ship ''Maro''. The island may be the last remnant of one of the largest volcanoes on Earth. It holds the record for the largest and hottest
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
.


History

The Gardner Pinnacles were first discovered on June 2, 1820, by the American
whaler A whaler or whaling ship is a specialized vessel, designed or adapted for whaling: the catching or processing of whales. Terminology The term ''whaler'' is mostly historic. A handful of nations continue with industrial whaling, and one, Jap ...
''Maro,'' commanded by Captain Joseph Allen. In 1859, the position of the Gardner Pinnacles was determined by the survey schooner USS ''Fenimore Cooper''. The Gardner Pinnacles are home to the giant opihi ('' Cellana talcosa''), a limpet known in Hawaiian as the , which is not found anywhere else in the world outside the Hawaiian Islands. Numerous insects live on the island. In 1903 the Gardner Pinnacles became a part of the Hawaiian Islands Bird Reservation. In 1940 it became a part of the Hawaiian Islands National Wildlife Refuge. In the 21st century it is part of
Papahānaumokuākea Marine National Monument The Papahānaumokuākea Marine National Monument (PMNM) (roughly ) is a World Heritage Site, World Heritage listed National monument (United States), U.S. national monument encompassing of ocean waters, including ten islands and atolls of th ...
wildlife refuge. The Gardner Pinnacles were used as an emergency helicopter landing spot for the Hawaiian HIRAN project, an effort to determine the locations of area islands with great precision for navigational purposes. In the Hawaiian Archipelago, adjacent islands/reefs are
French Frigate Shoals The French Frigate Shoals (Hawaiian language, Hawaiian: Kānemilohai) is the largest atoll in the Northwestern Hawaiian Islands, located about northwest of Honolulu, Hawaii, Honolulu. Its name commemorates France, French explorer Jean-Fran ...
to the southeast, and Maro Reef to the northwest.


Geology

The island is made up of
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
rock, which comes from lava erupted between 14 and 12 million years ago. The rock is dark grey and dense, and has a high
forsterite Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich Endmember, end-member of the olivine solid solution series. It is Isomorphism (crystallography), isomorphous with the iron-rich end-member, fayalit ...
content implying the
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
source was at . According to a 2020 report in ''
Earth and Planetary Science Letters ''Earth and Planetary Science Letters'' (EPSL) is a bimonthly peer-reviewed scientific journal covering research on physical, chemical and mechanical processes of the Earth and other planets, including extrasolar ones. Topics covered range from de ...
'', Pūhāhonu contains approximately of rock, based on a 2014 sonar survey. This would make it Earth's largest single volcano. Only about one-third of that volume is exposed above the sea floor while the rest is buried beneath a ring of debris, broken coral, and other material that has eroded from the peak. By comparison, from sea floor to peak,
Mauna Kea Mauna Kea (, ; abbreviation for ''Mauna a Wākea''); is a dormant Shield volcano, shield volcano on the Hawaii (island), island of Hawaii. Its peak is above sea level, making it the List of U.S. states by elevation, highest point in Hawaii a ...
, on Hawaii's Big Island, is the tallest
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
on Earth, but it is nowhere near as massive as Pūhāhonu. Another volcano on the Big Island is Mauna Loa; a 2013 study estimates Mauna Loa's volume at which is believed to be an overestimate. Pūhāhonu is so heavy, researchers note, that it has caused Earth's crust nearby—and thus the volcano itself—to sink hundreds of meters over millions of years. The Puhahonu volcano (Gardner) would be twice as big as Mauna Loa's based on that research. The Pūhāhonu and West Pūhāhonu volcanoes result from the Hawaii hotspot which is fed by the Hawaiian plume which had a major magmatic flux pulse at the time. A longer magmatic flux pulse produced the Hawaiian Islands. The five seamounts of the Naifeh Chain to the north of Pūhāhonu have a completely different tectonic origin, and are older (
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...
). At one time they were hypothesised to be related to the Pūhāhonu volcano because of arch volcanism, which can not be the case, given the newly determined age difference.


Ecology

The island has one plant known to grow on it, the succulent sea purslane. However, there are over a dozen species of bird observed here, many nesting. There is also a variety of insect species on the island. In the surrounding waters there is a variety of sealife, which is noted as habitat for a limpet, the giant ophi which lives in tidal areas of the rocky island. There are many species of fish and coral life in the nearby waters. The large numbers of birds have coated many surfaces of the island in
guano Guano (Spanish from ) is the accumulated excrement of seabirds or bats. Guano is a highly effective fertiliser due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a le ...
, giving it a whitish appearance. Some of the fish species in the nearby waters include red lip parrotfish, doublebar
goatfish The goatfishes are ray-finned fish of the family Mullidae, the only family in the suborder Mulloidei of the order Syngnathiformes. The family is also sometimes referred to as the red mullets, which also refers more narrowly to the genus '' Mul ...
, and reef triggerfish.


Name

The name Gardner comes from its discovery in 1820, when the Captain Joseph Allen of the ship ''Maro'' named it Gardner's Island. They also discovered Maro Reef, which is named for that sailing ship. It has sometimes been called Gardner Rock or Gardner Island, besides the Gardner Pinnacles. The Hawaiian name, ''Pūhāhonu'', means 'turtle surfacing for air', from ''pūhā'' 'to breathe at the surface' and ''honu'' 'turtle'.


See also

* List of volcanoes in the Hawaiian – Emperor seamount chain * Nikumaroro (aka Gardner Island)


Notes


References


External links


Gardner Pinnacles
Islands of the Hawaiian Chain

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Bishop Museum The Bernice Pauahi Bishop Museum, designated the Hawaii State Museum of Natural and Cultural History, is a museum of history and science in the historic Kalihi district of Honolulu, Hawaii, Honolulu on the Hawaiian island of Oʻahu. Founded in 1 ...

Quick Facts on the Gardner Pinnacles
– from the PBS Ocean Adventures
Papahānaumokuākea Marine National Monument Information Management System
{{authority control Northwestern Hawaiian Islands Hawaiian–Emperor seamount chain Rock formations of Hawaii Miocene volcanoes Paleogene Oceania Cenozoic Hawaii Stacks of the United States Important Bird Areas of Hawaii