Guyot

In marine geology, a guyot (pronounced /ɡiːˈjoʊ/), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi).[1] Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean.

Bear Seamount guyot
The Bear Seamount (left), a guyot in the northern Atlantic Ocean

History

Guyots were first recognized in 1945 by Harry Hammond Hess, who collected data using echo-sounding equipment on a ship he commanded during World War II.[2] His data showed that some undersea mountains had flat tops. Hess called these undersea mountains "guyots", because they resembled the flat-roofed biology and geology building at Princeton University, Guyot Hall, named after the 19th-century geographer Arnold Henry Guyot.[3] Hess postulated they were once volcanic islands that were beheaded by wave action, yet they are now deep under sea level. This idea was used to help bolster the theory of plate tectonics.[2]

Formation

Guyots show evidence of having once been above the surface, with gradual subsidence through stages from fringed reefed mountain, coral atoll, and finally a flat-topped submerged mountain.[1] Seamounts are made by extrusion of lavas piped upward in stages from sources within the Earth's mantle, usually hotspots, to vents on the seafloor. The volcanism invariably ceases after a time, and other processes dominate. When an undersea volcano grows high enough to be near or breach the ocean surface, wave action and/or coral reef growth tend to create a flat-topped edifice. However, all ocean crust and guyots form from hot magma and/or rock, which cools over time. As the lithosphere that the future guyot rides on slowly cools, it becomes denser and sinks lower into Earth's mantle, through the process of isostasy. In addition, the erosive effects of waves and currents are found mostly near the surface: the tops of guyots generally lie below this higher-erosion zone.

This is the same process that gives rise to higher seafloor topography at oceanic ridges, such as the Mid-Atlantic Ridge in the Atlantic Ocean, and deeper ocean at abyssal plains and oceanic trenches, such as the Mariana Trench. Thus, the island or shoal that will eventually become a guyot slowly subsides over millions of years. In the right climatic regions, coral growth can sometimes keep pace with the subsidence, resulting in coral atoll formation, but eventually the corals dip too deep to grow and the island becomes a guyot. The greater the amount of time that passes, the deeper the guyots become.[4]

Seamounts provide data on movements of tectonic plates on which they ride, and on the rheology of the underlying lithosphere. The trend of a seamount chain traces the direction of motion of the lithospheric plate over a more or less fixed heat source in the underlying asthenosphere, the part of the Earth's mantle beneath the lithosphere.[5] There are thought to be up to an estimated 50,000 seamounts in the Pacific basin.[6] The Hawaiian–Emperor seamount chain is an excellent example of an entire volcanic chain undergoing this process, from active volcanism, to coral reef growth, to atoll formation, to subsidence of the islands and becoming guyots.

Characteristics

The steepness gradient of most guyots is about 20 degrees. To technically be considered a guyot or tablemount, they must stand at least 900 m (3,000 ft) tall.[7] One guyot in particular, the Great Meteor Tablemount in the Northeast Atlantic Ocean, stands at more than 4,000 m (13,000 ft) high, with a diameter of 110 km (68 mi).[8] However, there are many undersea mounts that can range from just less than 90 m (300 ft) to around 900 m (3,000 ft).[7] Very large oceanic volcanic constructions, hundreds of kilometres across, are called oceanic plateaus.[9] Guyots are much larger in area (mean of 3,313 km2 (1,279 sq mi)) than typical seamounts (mean area of 790 km2 (310 sq mi)).[10]

There are 283 known guyots in the world's oceans, with the North Pacific having 119, the South Pacific 77, the South Atlantic 43, the Indian Ocean 28, the North Atlantic eight, the Southern Ocean six, and the Mediterranean Sea two; there are none known in the Arctic Ocean, though one is found along the Fram Strait off northeastern Greenland.[11] Guyots are also associated with specific lifeforms and varying amounts of organic matter. Local increases in chlorophyll a, enhanced carbon incorporation rates and changes in phytoplankton species composition are associated with guyots and other seamounts.[12]

See also

References

  1. ^ a b Guyot Encyclopædia Britannica Online, 2010. Retrieved January 14, 2010.
  2. ^ a b Bryson, Bill. "A Short History of Nearly Everything". New York: Broadway, 2003. p. 178
  3. ^ Guyot, Arnold in A Princeton Companion
  4. ^ "Guyot". www.utdallas.edu. Retrieved 15 January 2019.
  5. ^ Seamounts are made by extrusion of lavas piped upward in stages from sources within the Earth's mantle to vents on the seafloor. Seamounts provide data on movements of tectonic plates on which they ride, and on the rheology of the underlying lithosphere. The trend of a seamount chain traces the direction of motion of the lithospheric plate over a more or less fixed heat source in the underlying asthenosphere part of the Earth's mantle.
  6. ^ Hillier, J. K. (2007). "Pacific seamount volcanism in space and time". Geophysical Journal International. 168 (2): 877–889. Bibcode:2007GeoJI.168..877H. doi:10.1111/j.1365-246X.2006.03250.x.
  7. ^ a b "Seamount and guyot". Access Science. doi:10.1036/1097-8542.611100. Retrieved 2 February 2016.
  8. ^ "Great Meteor Tablemount (volcanic mountain, Atlantic Ocean) – Britannica Online Encyclopedia". britannica.com. Retrieved 15 January 2019.
  9. ^ "Answers - The Most Trusted Place for Answering Life's Questions". Answers.com. Retrieved 15 January 2019.
  10. ^ Harris, P.T.; Macmillan-Lawler, M.; Rupp, J.; Baker, E.K. (2014). "Geomorphology of the oceans". Marine Geology. 352: 4–24. Bibcode:2014MGeol.352....4H. doi:10.1016/j.margeo.2014.01.011.
  11. ^ . doi:10.1002/2015GC0059310 (inactive 2019-08-20). Cite journal requires |journal= (help); Missing or empty |title= (help)
  12. ^ Sahfos

External links

Allison Guyot

Allison Guyot (formerly known as Navoceano Guyot) is a tablemount (guyot) in the underwater Mid-Pacific Mountains of the Pacific Ocean. It is a trapezoidal flat mountain rising 1,500 metres above the seafloor to a depth of less than 1,500 m, with a summit platform 35 by 70 kilometres wide. The Mid-Pacific Mountains lie west of Hawaii and northeast of the Marshall Islands, but at the time of their formation were located in the Southern Hemisphere.

The tablemount was probably formed by a hotspot in the present-day Southern Pacific before plate tectonics moved it to its current location. Several hotspots, including the Easter, Marquesas and Society hotspots, may have been involved in the formation of the Mid-Pacific Mountains. Volcanic activity is dated to have occurred circa 111–85 million years ago and formed a volcanic island. Subsequently, carbonate deposition commenced as Allison Guyot subsided and eventually buried the island, forming an atoll-like structure and a carbonate platform. Among other animals, crocodilians lived on Allison Guyot.

The platform emerged above sea level during the Albian and Turonian ages. It drowned about 99 ± 2 million years ago for unknown reasons; possibly a phase of renewed emergence damaged the reefs, or it was located in unfavourable waters. Later, pelagic sedimentation commenced on the seamount and led to the deposition of sediments including limestone, ooze and sand, which bear traces of climatic events and ocean currents.

Arnold Henry Guyot

Arnold Henry Guyot ( GHEE-oh) (September 28, 1807 – February 8, 1884) was a Swiss-American geologist and geographer.

Charles Guyot (cyclist)

Charles Guyot (4 August 1890 – 30 April 1958) was a Swiss racing cyclist. He was the Swiss National Road Race champion in 1909 and 1910. He also rode in three editions of the Tour de France.

Daikakuji Guyot

Daikakuji Seamount is a seamount (underwater volcano) and the southwesternmost volcanic feature in the Hawaiian Emperor chain bend area.

Horizon Guyot

Horizon Guyot is a presumably Cretaceous guyot (tablemount) in the Mid-Pacific Mountains, Pacific Ocean. It is an elongated ridge, over 300 kilometres (190 mi) long and 4.3 kilometres (2.7 mi) high, that stretches in a northeast-southwest direction and has two flat tops; it rises to a minimum depth of 1,443 metres (4,730 ft). The Mid-Pacific Mountains lie west of Hawaii and northeast of the Line Islands.

It was probably formed by a hotspot, but the evidence is conflicting. Volcanic activity occurred during the Turonian-Cenomanian eras 100.5–89.8 million years ago and another stage has been dated to have occurred 88–82 million years ago. Between these volcanic episodes, carbonate deposition from lagoonal and reefal environments set in and formed limestone. Volcanic islands developed on Horizon Guyot as well and were colonised by plants.

Horizon Guyot became a seamount during the Coniacian-Campanian period. Since then, pelagic ooze has accumulated on the seamount, forming a thick layer that is further modified by ocean currents and by various organisms that live on the seamount; sediments also underwent landsliding. Ferromanganese crusts were deposited on exposed rocks.

Jingū Seamount

Jingū Seamount, also called Jingū Guyot, is a guyot of the Hawaiian-Emperor seamount chain in the Pacific Ocean. It erupted 55 million years ago. The seamount is elongated in structure, running north–south, and has an oval shaped crater in the center, which is evidence of collapse when above sea level.The seamount was named in 1954 by Robert S. Dietz, after Japanese Empress Jingū.

Koko Guyot

Koko Guyot (also sometimes known as Kinmei and Koko Seamount) is a 48.1-million-year-old guyot, a type of underwater volcano with a flat top, which lies near the southern end of the Emperor seamounts, about 200 km (124 mi) north of the "bend" in the volcanic Hawaiian-Emperor seamount chain. Pillow lava has been sampled on the north west flank of Koko Seamount, and the oldest dated lava is 40 million years old. Seismic studies indicate that it is built on a 9 km (6 mi) thick portion of the Pacific Plate. The oldest rock from the north side of Koko Seamount is dated at 52.6 and the south side of Koko at 50.4 million years ago. To the southeast of the bend is Kimmei Seamount at 47.9 million years ago and southeast of it, Daikakuji at 46.7.

Laurent Guyot

Laurent Guyot (born 17 December 1969) is a French former footballer and football manager, currently managing Boulogne in the French Championnat National.

Lawrence Guyot

Lawrence Guyot Jr. (July 17, 1939 – November 23, 2012) was an American civil rights activist who was the director of the Mississippi Freedom Democratic Party in 1964.

Guyot, a native of Pass Christian, Mississippi joined the Freedom Movement in Mississippi in 1961, when he was a student at Tougaloo College in Mississippi. He graduated with a bachelor's degree in biology and chemistry in 1963. Guyot also directed the Congress of Racial Equality (CORE) project in Hattiesburg, Mississippi, and later became director of the Mississippi Freedom Democratic Party via the 1963 Freedom Ballot of 80,000 participants and the Summer Project of 1964. The major accomplishment of SNCC/MFDP was to establish a close bond with the United States Department of Justice. In 1966, Guyot ran for Congress as an anti-war candidate. Guyot was severely beaten many times, including while at the Mississippi State Penitentiary known as Parchman Farm, in the early 1960s stating of his testicles being burned with sticks by police officers. Guyot helped lay the groundwork for the Voting Rights Act of 1965. He received a degree in law in 1971 from Rutgers University, and then moved to Washington, D.C., where he worked for the election of Marion Barry as mayor in 1978.

Muhammad Ali, the world boxing champion, was a good friend of Lawrence Guyot.

He has appeared in many documentaries such as Eyes on the Prize in 1987. From the 1990s until the mid-2000s, Guyot often appeared as a commentator on Fox News, defending the legacy of the civil rights movement in heated discussions with hosts Bill O'Reilly and Sean Hannity. He continued speaking out on voting rights issues and encouraged people to vote for President Barack Obama. Until his retirement in 2004, Guyot was a program monitor for the D.C. Department of Human Services’ Office of Early Childhood Development.

His daughter Dr Julie Guyot-Diangone announced on November 24, 2012, that her father died at home in Mount Rainier, Maryland. She said he had heart problems and suffered from diabetes. In addition to his daughter, Guyot is survived by his wife of 47 years, Monica Klein Guyot, a son, Lawrence Guyot III of La Paz, Bolivia, and four grandchildren.

Mount Chapman

Mount Chapman is a mountain in the Great Smoky Mountains, located in the Southeastern United States. It has an elevation of 6,417 feet (1,956 m) above sea level.[1] While the mountain is located deep within the Great Smokies, the Appalachian Trail crosses its eastern slope, coming to within 200 feet (61 m) of the summit. Mount Chapman is among the 10 highest mountains in the Appalachian range, if subpeaks are not included.[2]

Mount Chapman is situated along the Tennessee-North Carolina border, with Sevier County to the north and Swain County to the south. Like its neighbor Mount Guyot, Chapman is a double peak, with the southern peak being the true summit. A 1,500-foot (460 m) gap divides Chapman from Dashoga Ridge (i.e., Mount Hardison and Marks Knob), just two miles (3 km) to the east.[3] Mount Chapman's western slope, known as Chapman Lead, is more gradual, descending roughly 4,000 feet (1,200 m) over 5 miles (8.0 km) to its base along the headwaters of the Little Pigeon River.[4] Chapman Lead parallels Guyot Spur to the north, with Buck Fork slicing between the two giant ridges. The mountain's summit is coated in a dense stand of Southern Appalachian spruce-fir forest.

The remoteness of Mount Chapman has left it largely untouched by human history. The mountain is named after Colonel David C. Chapman (1876-1944), a Knoxville business leader who led efforts to establish a national park in the Great Smokies. As head of the Tennessee Great Smoky Mountains Park Commission from 1927-1937, Chapman raised funds and negotiated hundreds of land purchases that would make the park possible. Arnold Guyot crossed Mount Chapman in the late 1850s, measuring the mountain's summit at 6,447 feet (Guyot called it "Mount Alexander" after a Princeton colleague). The leg of the Appalachian Trail crossing Chapman's eastern slope was constructed in 1935.

Mount Chapman is approximately 11 miles (18 km) from the nearest parking lot at the Cosby Campground and 14.5 miles (23.3 km) from Newfound Gap. From the Cosby Campground (specifically behind Campsite B51), the Snake Den Ridge Trail winds for 5.3 miles (8.5 km) to its junction with the Appalachian Trail at Inadu Knob. Following the AT from Inadu, Chapman's main peak is approximately 5.2 miles (8.4 km) to the south, with the trail first crossing the slopes of Old Black, Mount Guyot, and Tricorner Knob. A short bushwhack is required to reach the summit.

The Tricorner Knob Shelter is approximately 1.5 miles (2.4 km) to the northeast of Mount Chapman.

Mount Guyot (Colorado)

Mount Guyot is a high mountain summit in the Front Range of the Rocky Mountains of North America. The 13,376-foot (4,077 m) thirteener is located 6.3 miles (10.2 km) east-southeast (bearing 117°) of the Town of Breckenridge, Colorado, United States, on the Continental Divide separating Pike National Forest and Park County from Arapaho National Forest and Summit County. The mountain was named in honor of Arnold Henry Guyot, a Swiss-American geologist.

Mount Guyot (Great Smoky Mountains)

Mount Guyot is a mountain in the eastern Great Smoky Mountains, located in the southeastern United States. At 6,621 feet (2,018 m) in elevation, Guyot is the fourth-highest summit in the eastern U.S., and the second-highest in the Great Smoky Mountains National Park. While the mountain is remote, the Appalachian Trail crosses its south slope, passing to within 1,000 feet (300 m) of the summit.

Mount Guyot lies on the Tennessee-North Carolina border, between Sevier County and

Haywood County. There are two peaks atop the mountain, appx. one-half mile apart,

with the southwestern peak being the true summit. The mountain rises 3,600 feet (1,100 m) above its

eastern base near Walnut Bottom and 4,000 feet (1,200 m) above its western base near Greenbrier Cove. Ramsey Cascades, one of the park's most spectacular waterfalls, spills down a sandstone cliff near the bottom of Guyot's western

slope.

A dense stand of Southern Appalachian spruce-fir forest coats the summit and upper slopes of Guyot. Human settlement never expanded deep into the eastern Smokies, so the area around Guyot and adjacent peaks suffered substantially less disturbance than the mountains in the western or central parts of the range. A long hike and a challenging bushwhack are required to reach the summit, the highest in the East without a trail.

Mount Guyot (New Hampshire)

Mount Guyot is a mountain located in Grafton County, New Hampshire. The mountain is named after Professor Arnold H. Guyot (1807–1884) of Princeton University, and is part of the Twin Range of the White Mountains.

Mount Guyot is flanked to the northwest by South Twin Mountain, to the northeast by Mount Zealand, and to the south by Mount Bond. Guyot is on the northern boundary of the Pemigewasset Wilderness. The immediate area around the summit consists of high-altitude spruce-fir forest or krummholz.

The north face of Mount Guyot drains into the Little River, thence into the Ammonoosuc and Connecticut rivers, and into Long Island Sound in Connecticut. The southeast face of Guyot drains into Jumping Brook, thence into the North Fork of the East Branch of the Pemigewasset River, thence into the Pemigewasset and Merrimack rivers, and into the Gulf of Maine in Massachusetts. The southwest face of Guyot drains into the Franconia Branch of the East Branch of the Pemigewasset River.

The Appalachian Trail, a 2,170-mile (3,500-km) National Scenic Trail from Georgia to Maine, runs along the ridges from South Twin to Zealand, crossing the summit of Guyot. Although well over 4,000 feet (1,200 m) in height, the Appalachian Mountain Club doesn't consider Mount Guyot a "four-thousand footer" because it stands less than 200 ft (61 m) above the col separating it from South Twin Mountain.

Ojin Seamount

Ōjin Seamount, also called Ōjin Guyot, named after Emperor Ōjin, 15th Emperor of Japan, is a guyot of the Hawaiian-Emperor seamount chain in the Pacific Ocean. It erupted 55 million years ago.

Suiko Seamount

Suiko Seamount, also called Suiko Guyot, is a guyot of the Hawaiian-Emperor seamount chain in the Pacific Ocean.

Vine training

The use of vine training systems in viticulture is aimed primarily to assist in canopy management with finding the balance in enough foliage to facilitate photosynthesis without excessive shading that could impede grape ripening or promote grape diseases. Additional benefits of utilizing particular training systems could be to control potential yields and to facilitate mechanization of certain vineyard tasks such as pruning, irrigation, applying pesticide or fertilizing sprays as well as harvesting the grapes.In deciding on what type of vine training system to use, growers will also consider the climate conditions of the vineyard where the amount of sunlight, humidity and wind could have a large impact on the exact benefits the training system offers. For instance, while having a large spread out canopy (such as what the Geneva Double Curtain offers) can promote a favorable leaf to fruit ratio for photosynthesis, it offers very little wind protection. In places such as the Châteauneuf-du-Pape, strong prevailing winds such as le mistral can take the fruit right off the vine so a more condensed, protective vine training system is desirable for vineyards there.While closely related, the terms trellising, pruning and vine training are often used interchangeably even though they refer to different things. Technically speaking, the trellis refers to the actual stakes, posts, wires or other structures that the grapevine is attached to. Some vines are allowed to grow free standing without any attachment to a trellising structure. Part of the confusion between trellising and vine training systems stems from the fact that vine training systems will often take on the name of the particular type of trellising involved. Pruning refers to the cutting and shaping of the cordon or "arms" of the grapevine in winter which will determine the number of buds that are allowed to become grape clusters. In some wine regions, such as France, the exact number of buds is outlined by Appellation d'origine contrôlée (AOC) regulations. During the summer growing season, pruning can involve removing young plant shoots or excess bunches of grapes with green harvesting. Vine training systems utilize the practice of trellising and pruning in order to dictate and control a grape vine's canopy which will influence not only the potential yield of that year's crop but also the quality of the grapes due to the access of air and sunlight needed for the grapes to ripen fully and for preventing various grape diseases.

Winnipeg

Winnipeg ( (listen)) is the capital and largest city of the province of Manitoba in Canada. Centred on the confluence of the Red and Assiniboine rivers, it is near the longitudinal centre of North America, approximately 110 kilometres (70 mi) north of the Canada–United States border.

The city is named after the nearby Lake Winnipeg; the name comes from the Western Cree words for muddy water. The region was a trading centre for Indigenous peoples long before the arrival of Europeans. French traders built the first fort on the site in 1738. A settlement was later founded by the Selkirk settlers of the Red River Colony in 1812, the nucleus of which was incorporated as the City of Winnipeg in 1873. As of 2011, Winnipeg is the seventh most populated municipality in Canada. Being far inland, the local climate is extremely seasonal even by Canadian standards with average January lows of around −21 °C (−6 °F) and average July highs of 26 °C (79 °F).Known as the "Gateway to the West", Winnipeg is a railway and transportation hub with a diversified economy. This multicultural city hosts numerous annual festivals, including the Festival du Voyageur, the Winnipeg Folk Festival, the Jazz Winnipeg Festival, the Winnipeg Fringe Theatre Festival, and Folklorama. Winnipeg was the first Canadian host of the Pan American Games. It is home to several professional sports franchises, including the Winnipeg Blue Bombers (Canadian football), the Winnipeg Jets (ice hockey), Manitoba Moose (ice hockey), Valour FC (soccer), and the Winnipeg Goldeyes (baseball).

Yuryaku Seamount

Yuryaku Seamount (also called Yuryaku Guyot) is a seamount (underwater volcano) and guyot (flat-topped) located northwest of Hawaii. It is located a little southwest of the V-shaped bend separating the Emperor Seamounts from the older Hawaiian islands, all of the Hawaiian-Emperor seamount chain in the North Pacific Ocean.

Yves Guyot

Yves Guyot (6 September 1843 – 22 February 1928) was a French politician and economist.

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