Guyot
Encyclopedia
- For the French viticulturist, see Jules GuyotJules Guyotright|thumb|250 px| Le Château Savigny-lès-Beaune, where Jules Guyot died in 1872Dr. Jules Guyot was a French physician and agronomist who was born in the commune of Gyé-sur-Seine in the department of Aube...
. For the Old French name, see GuiotGuiotGuiot or Guyot is an Old French name, an augmentative of Guy, that could refer to:*Guiot de Dijon*Guiot or Guyot du Repaire*Guiot de Provins*Guyot*Jules Guyot French physician*Claude-Étienne Guyot...
.
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
), with a flat top over 200 meters (660 feet) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi).
The guyot was named after the Swiss-American geographer and geologist Arnold Henry Guyot
Arnold Henry Guyot
Arnold Henry Guyot was a Swiss-American geologist and geographer.-Biography:...
(died 1884). The term was coined by Harry Hammond Hess
Harry Hammond Hess
Harry Hammond Hess was a geologist and United States Navy officer in World War II.Considered one of the "founding fathers" of the unifying theory of plate tectonics, Rear Admiral Harry Hammond Hess was born on May 24, 1906 in New York City...
. Guyots are most commonly found in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. Guyots show evidence of having been above the surface with gradual subsidence through stages from fringed reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
ed mountain, coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
atoll
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...
, and finally a flat topped submerged mountain. Their flatness is due to erosion by waves, winds, and atmospheric processes. The steepness gradient of most guyots is about 20 degrees. To technically be considered a guyot or tablemount, they must stand at least 3000 ft (900 m) tall. However, there are many undersea mounts that can range from just less than 300 ft to around 3000 ft. Very large oceanic volcanic constructions, hundreds of kilometers across, are called oceanic plateau
Oceanic plateau
An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope, some plateaus are undersea remnants of large igneous...
s. 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
Rheology
Rheology is the study of the flow of matter, primarily in the liquid state, but also as 'soft solids' or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force....
of the underlying lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's 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
Asthenosphere
The asthenosphere is the highly viscous, mechanically weak and ductilely-deforming region of the upper mantle of the Earth...
part of the Earth's mantle. There are thought to be an estimated 2,000 seamounts in the Pacific basin. The Emperor Seamounts are an excellent example of an entire volcanic chain undergoing this process and contain many guyots among their other examples.
Another factor contributing to the guyots being underwater has to do with the oceanic ridges, such as the Mid-Atlantic Ridge in the Atlantic Ocean. Mid-ocean ridges gradually spread apart over time, due to molten lava being pushed up under the surface of the earth and creating new rock. As the mid-ocean ridges spread apart, the guyots move with them, thus continually sinking deeper into the depths of the ocean. Thus, the greater amount of time that passes, the deeper the guyots become. Although guyots can be hundreds of millions of years old, there have been some recently discovered guyots that were only formed within the last 1 million years, including Bowie Seamount
Bowie Seamount
Bowie Seamount is a large submarine volcano in the northeastern Pacific Ocean, located west of Haida Gwaii, British Columbia, Canada.The seamount is named after William Bowie of the Coast & Geodetic Survey....
on the coast of British Columbia
British Columbia Coast
The British Columbia Coast or BC Coast is Canada's western continental coastline on the Pacific Ocean. The usage is synonymous with the term West Coast of Canada....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
One guyot in particular, the Great Meteor Tablemount
Great Meteor Seamount
The Great Meteor Seamount is a large guyot located south of the Azores in the Atlantic Ocean. It is the New England hotspot's most recent eruptive center and is one of the most completely investigated seamounts in the world. This guyot rises up from a depth of almost 4,800 meters to about 270...
in the Northeast Atlantic Ocean, stands at more than 4000 m (13,120 ft). The guyot's diameter is 110 km (68.4 mi). 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 were associated with the seamount.
Guyots were first recognized by Harry Hammond Hess
Harry Hammond Hess
Harry Hammond Hess was a geologist and United States Navy officer in World War II.Considered one of the "founding fathers" of the unifying theory of plate tectonics, Rear Admiral Harry Hammond Hess was born on May 24, 1906 in New York City...
in 1965 who collected data using echo-sounding equipment on a ship he commanded during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. The data showed the configuration of the seafloor where he saw that some undersea mountains had flat tops.
Hess called these undersea mountains 'guyots' because they resembled Guyot Hall, the flat roofed geology building at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
which was itself named after the 18th century geographer Arnold Henry Guyot
Arnold Henry Guyot
Arnold Henry Guyot was a Swiss-American geologist and geographer.-Biography:...
.
Hess postulated they were once volcanic islands that were beheaded by wave action yet they are now deep under sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
. This idea was used to help bolster the theory of plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
.
See also
- Hawaiian-Emperor seamount chainHawaiian-Emperor seamount chainThe Hawaiian–Emperor seamount chain is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts, a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending...
- New England Seamount chainNew England Seamount chainThe New England Seamount chain is an underwater chain of seamounts in the Atlantic Ocean stretching over 1,000 kilometers from the edge of the Georges Bank off the coast of Massachusetts. The chain consists of over twenty extinct volcanic peaks, many rising over 4,000 meters from the seabed...
- Kodiak-Bowie Seamount chainKodiak-Bowie Seamount chainThe Kodiak–Bowie Seamount chain, also called the Pratt–Welker Seamount chain, is a seamount chain in southeastern Gulf of Alaska stretching from the Aleutian Trench in the north to Bowie Seamount, the youngest volcano in the chain, which lies west of the Queen Charlotte Islands,...
- Evolution of Hawaiian volcanoesEvolution of Hawaiian volcanoesThe fifteen volcanoes that make up the eight principal islands of Hawaii are the youngest in a chain of more than 129 volcanoes that stretch across the North Pacific Ocean, called the Hawaiian-Emperor seamount chain....
- Hotspot (geology)Hotspot (geology)The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...
- AtollAtollAn atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...
- SeamountSeamountA seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...