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27-692: The Bear Seamount is a guyot or flat-topped underwater volcano in the Atlantic Ocean . It is the oldest of the New England Seamounts , which was active more than 100 million years ago. It was formed when the North American Plate moved over the New England hotspot . It is located inside the Northeast Canyons and Seamounts Marine National Monument , which was proclaimed by President of

54-821: A mean area of 3,313 km (1,279 sq mi), which is much larger than typical seamounts, which have a mean area of 790 km (310 sq mi). 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

81-409: A time, and other processes dominate. When an undersea volcano grows high enough to be near or breach the ocean surface, wave action or coral reef growth tend to create a flat-topped edifice. However, all ocean crust and guyots form from hot magma 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

108-711: The American Philosophical Society in 1960. He was president of The Geological Society of America in 1963 and received their Penrose Medal in 1966. In 1968, he was elected to the American Academy of Arts and Sciences . Hess died from a heart attack in Woods Hole, Massachusetts , on August 25, 1969, while chairing a meeting of the Space Science Board of the National Academy of Sciences . He

135-546: 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. Seamounts provide data on movements of tectonic plates on which they ride, and on

162-588: The Marianas , Philippines , and Iwo Jima , continuously using his ship's echo sounder . This unplanned wartime scientific surveying enabled Hess to collect ocean floor profiles across the North Pacific Ocean , resulting in the discovery of flat-topped submarine volcanoes, which he termed guyots , after the 19th-century geographer Arnold Henry Guyot . After the war, he remained in the Naval Reserve , rising to

189-537: The Pleistocene . Because little was known about the biodiversity of the New England Seamount Chain, an expedition was mounted in 2000. The NOAA National Marine Fisheries Service deep water research vessel R/V Delaware II made 20 exploratory trawls in the vicinity of Bear Seamount and around 274 species were collected. These included 115 species of fish, some of which were rare or had not been recorded in

216-737: The U.S. Navy Hydrographic Office in The Navy-Princeton gravity expedition to the West Indies in 1932 . Hess joined the United States Navy during World War II, becoming captain of the USS Cape Johnson , an attack transport ship equipped with a new technology: sonar . This command would later prove to be key in Hess's development of his theory of sea floor spreading . Hess carefully tracked his travel routes to Pacific Ocean landings on

243-642: 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. There are thought to be up to an estimated 50,000 seamounts in the Pacific basin. 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

270-554: The Arctic Ocean, though one is found along the Fram Strait off northeastern Greenland . 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 . Harry Hammond Hess Harry Hammond Hess (May 24, 1906 – August 25, 1969)

297-613: The North Pacific Ocean after Marie Tharp and Bruce Heezen (1953, Lamont Group ) discovered the Great Global Rift , running along the Mid-Atlantic Ridge . Seafloor spreading , as the process was later named, helped establish Alfred Wegener 's earlier (but generally dismissed at the time) concept of continental drift as scientifically respectable. This triggered a revolution in the earth sciences. Hess's report

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324-615: The United States Barack Obama to protect the seamount's biodiversity. The Bear Seamount is the first guyot in a chain of about 30 extinct volcanoes extending in a straight line south-eastwards from the edge of the continental shelf near Woods Hole, Massachusetts to north-east of Bermuda . These seamounts resulted from the movement of a mantle plume hotspot. This hotspot is now under the Great Meteor Seamount . The chain rises about 4,000 metres (13,000 ft) above

351-533: The faculty of Princeton University in 1934. Hess remained at Princeton for the rest of his career and served as Geology Department Chairman from 1950 to 1966. He was a visiting professor at the University of Cape Town , South Africa (1949–1950), and the University of Cambridge , England (1965). Hess accompanied Dr. Felix Vening Meinesz of Utrecht University on board the US Navy submarine USS S-48 to assist with

378-786: The islands and becoming guyots. 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. 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). However, there are many undersea mounts that can range from just less than 90 m (300 ft) to around 900 m (3,000 ft). Very large oceanic volcanic constructions, hundreds of kilometres across, are called oceanic plateaus . Guyots have

405-444: The lower flanks of the chain. Bear Seamount rises approximately 2,000 to 3,000 metres (6,600 to 9,800 ft) above the surrounding seabed and the roughly flat summit is about 1,100 metres (3,600 ft) below the surface of the sea. The top is covered by a deep layer of sediment through which basaltic rocks and erratic boulders protrude. Much of this material has fallen from above, probably from icebergs that drifted southwards during

432-456: 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

459-481: The rank of rear admiral . In 1960, Hess made his single most important contribution, which is regarded as part of the major advance in geologic science of the 20th century. In a widely circulated report to the Office of Naval Research , he advanced the theory, now generally accepted, that the Earth's crust moved laterally away from long, volcanically active oceanic ridges . He only understood his ocean floor profiles across

486-552: The sea star Neomorphaster forcipatus , mysids and various scyphozoans . Guyot 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 . His data showed that some undersea mountains had flat tops. Hess called these undersea mountains "guyots", after the 19th-century geographer Arnold Henry Guyot . Hess postulated they were once volcanic islands that were beheaded by wave action, yet they are now deep under sea level . This idea

513-448: The seamount surface included 46 species of crustacean such as the prawns Sergestes spp. and Acanthephyra spp. , and the shrimp Pasiphaea spp . Also present was the bank-forming deepwater coral Lophelia pertusa , which supported a community of worms, hydroids and other corals. Brittle stars, especially Ophiomusium lymani , were numerous as were the sea urchin Echinus affinis ,

540-466: The second U.S. expedition to obtain gravity measurements at sea. The expedition used a gravimeter , or gravity meter, designed by Meinesz. The submarine traveled a route from Guantanamo, Cuba , to Key West, Florida , and return to Guantanamo through the Bahamas and Turks and Caicos region from 5 February through 25 March 1932. The description of operations and results of the expedition were published by

567-492: The surrounding Sohm Abyssal Plain . Over time they have been eroded and have developed flat table-like summits surrounded by slopes with an inclination of about 20°. The currents in the vicinity of the Bear Seamount include the warm water Gulf Stream flowing towards the north east, the deep boundary current flowing along the continental shelf towards the south west, and the deep, icy cold Arctic bottom water that flows past

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594-592: The western North Atlantic before. The roundnose grenadier ( Coryphaenoides rupestris ) and the onion-eye grenadier ( Macrourus berglax ) were the only fish species of potential commercial importance – they were caught in mid-water at depths of between 1,100 and 1,800 metres (3,600 and 5,900 ft) and were up to a metre in length. A common but much smaller fish was Aldrovandia phalacra . Twenty-six species of cephalopods were collected including squid such as Mastigoteuthis agassizii and Mastigoteuthis magna . Other invertebrates caught by trawls dragged along

621-510: Was an American geologist and a United States Navy officer in World War II who is considered one of the "founding fathers" of the unifying theory of plate tectonics . He published theories on sea floor spreading , specifically on relationships between island arcs , seafloor gravity anomalies , and serpentinized peridotite , suggesting that the convection in the Earth's mantle is the driving force behind this process. Harry Hammond Hess

648-593: Was born on May 24, 1906, in New York City to Julian S. Hess, a member of the New York Stock Exchange , and Elizabeth Engel Hess. He attended Asbury Park High School in Asbury Park, New Jersey . In 1923, he entered Yale University , where he intended to study electrical engineering but ended up graduating with a Bachelor of Science degree in geology. Hess failed his first time taking mineralogy at Yale and

675-534: Was formally published in his History of Ocean Basins (1962), which for a time was the single most referenced work in solid-earth geophysics . Hess was also involved in many other scientific endeavours, including the Mohole project (1957–1966), an investigation onto the feasibility and techniques of deep sea drilling . Hess was elected to the United States National Academy of Sciences in 1952 and

702-632: Was told he had no future in the field. Despite this, he continued with his degree and was teaching geology at Princeton when World War II was declared. He spent two years as an exploration geologist in Northern Rhodesia . In 1934 he married Annette Burns. Harry Hess taught for one year (1932–1933) at Rutgers University in New Jersey and spent a year as a research associate at the Geophysical Laboratory of Washington, D. C. , before joining

729-446: Was used to help bolster the theory of plate tectonics . 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. 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

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