The Telegraph Plateau is a region of the

North Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for ...

that was supposedly relatively flat and shallow compared to the rest of the ocean away from shore. The term is archaic and no longer used by

hydrographer Hydrography is the branch of applied sciences which deals with the measurement and description of the physical features of oceans, seas, coastal areas, lakes and rivers, as well as with the prediction of their change over time, for the primary ...

s. It was so named because it seemed to be an ideal route for a

transatlantic telegraph cable Transatlantic telegraph cables were undersea cables running under the Atlantic Ocean for telegraph communications. Telegraphy is a largely obsolete form of communication, and the cables have long since been decommissioned, but telephone and dat ...

, and was actually used for the first such cable in 1858. The Victorian hydrographers surveying the route failed to notice the

Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a Divergent boundary, divergent or constructive Plate tectonics, plate boundary) located along the floor of the Atlantic Ocean, and part of the List of longest mountain chains on Earth, longest mountai ...

in the middle of the route.

Discovery and naming

The feature was discovered by

Matthew Fontaine Maury Matthew Fontaine Maury (January 14, 1806February 1, 1873) was an American oceanographer and naval officer, serving the United States and then joining the Confederacy during the American Civil War. He was nicknamed "Pathfinder of the Seas" and ...

while producing a

bathymetric chart A bathymetric chart is a type of isarithmic map that depicts the submerged bathymetry and physiographic features of ocean and sea bottoms. Their primary purpose is to provide detailed depth contours of ocean topography as well as provide the si ...

of the ocean in 1853, compiled from sounding data from multiple ships' logs. Maury so named it because he thought it would be an ideal route for a

, which at the time, was no more than a vague aspiration. His

s confirmed his assessment of the viability of the route using accurate sounders invented by

John Mercer Brooke John Mercer Brooke (December 18, 1826 – December 14, 1906) was an American sailor, engineer, scientist, and educator. He was instrumental in the creation of the Transatlantic Cable, and was a noted marine and military innovator. Early lif ...

. Brooke's sounder was designed to release the

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

immediately it contacted the bottom so that a sample of the sea bed could be recovered without the risk of the line breaking while it was being hauled back up due to the weight of the lead. Maury had discarded many of the historic readings because he thought they were inaccurate due to the inability of the sounder to tell when the

had contacted the bottom in deep ocean. This resulted in more line being run out before the reading was taken. Maury's solution to this problem was to determine the law of descent of the line for given sizes of line and weights of lead. Sounders were provided with tables of expected rates of line runout, so that once the rate was much less than that expected, they knew that the bottom had been reached. The feature occupied the shortest route between the

British Isles The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...

and the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

. The region begins at around 51° north and runs from near the south of Ireland to

Newfoundland Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the population ...

in Canada north of the

Great Banks The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting Atlantic cod, swordfis ...

for a distance of . Its average depth was measured at , and greatest depth . It was described as a table-land or

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the tropical and subtropica ...

(in comparison to the

Southern Andean Steppe The Southern Andean steppe is a montane grasslands and shrublands ecoregion occurring along the border of Chile and Argentina in the high elevations of the southern Andes mountain range. Setting This ecoregion is found from in the north to in t ...

), and sometimes called the ''Atlantic steppe''. To the south of the plateau, the

hydrography Hydrography is the branch of applied sciences which deals with the measurement and description of the physical features of oceans, seas, coastal areas, lakes and rivers, as well as with the prediction of their change over time, for the primary ...

was determined to be very uneven, with depths of between recorded, although six miles is a little beyond any depth marked on a modern chart. Maury's chart was instrumental in

Cyrus Field Cyrus West Field (November 30, 1819July 12, 1892) was an American businessman and financier who, along with other entrepreneurs, created the Atlantic Telegraph Company and laid the first telegraph cable across the Atlantic Ocean in 1858. Early ...

's decision to land the transatlantic cable in

. It showed that the region to the south of Telegraph Plateau was much too rugged to take a cable directly to the United States. The route had appeal, not only because it was flat, not too deep, and was the shortest route, but also because it had moderate currents which would help the cable to sink straight down and a soft seabed (made up of microscopic shells) for the cable to rest on. The Victorian hydrographers failed to detect the presence of the

due to the widely spaced soundings taken along the proposed cable route. The ridge is particularly narrow at this point and the hydrography on either side is relatively flat. The term ''Telegraph Plateau'' is no longer used by modern hydrographers.

Geology

Telegraph Plateau consists of

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...

plus a section of the

Reykjanes Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Am ...

(the northern branch of the Mid-Atlantic Ridge) where the plateau crosses from the Eurasian plate to the North American plate. The crossing is in the Charlie-Gibbs fracture zone between the

Minia Seamount Minia may refer to: *Munia (also called a "minia"), a bird of the genus ''Lonchura'' *Minya, Egypt, a city in Egypt *Minya Governorate Minya ( ') is one of the governorates of Upper Egypt. Its capital city, Minya, is located on the left bank o ...

Mountains to the north and the volcanic

Faraday Hills Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic inducti ...

to the south. Telegraph Plateau was once thought to be an ancient shield resembling

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

with a different

strike Strike may refer to: People *Strike (surname) * Hobart Huson, author of several drug related books Physical confrontation or removal *Strike (attack), attack with an inanimate object or a part of the human body intended to cause harm * Airstrike, ...

, and the fold belts around it suggested Caledonian folding. These features are now known to be much more recent and are a result of

plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

.Furlong ''et al.'', p. 82

References

Bibliography

* Barnes, Clifford A.; Broadus, James M.; Ericson, David Barnard; Fleming, Richard Howell; LaMourie, Matthew J.; Namias, Jerome
"Atlantic Ocean"
''Encyclopædia Britannica'' (online), Encyclopædia Britannica, Inc., retrieved 26 May 2020. * Kevin P. Furlong, Steven D. Sheaffer, Rocco Malservisi, "Thermal–rheological controls of deformation within ocean transforms", pp. 65–84 in, ''The Nature and Tectonic Significance of Fault Zone Weakening'', Geological Society of London, 2001 . * John Mullaly, ''The Laying of the Cable, or the Ocean Telegraph'', D. Appleton, 1858, . * Helen M. Rozwadowski, ''Fathoming the Ocean: The Discovery and Exploration of the Deep Sea'', Harvard University Press, 2009 . * Jacob Ward
"Oceanscapes and spacescapes in North Atlantic communications: Laying cables"
ch. 10 in, Jon Agar, Jacob Ward (eds), Robert E. Holdsworth, R. A. Strachan, J. Magloughlin, R. J. Knipe (eds), ''Histories of Technology, the Environment and Modern Britain'', UCL Press, retrieved 8 May 2020. * N. Zhirov, ''Atlantis: Atlantology: Basic Problems'', University Press of the Pacific, 2001 (1970 reprint) . {{coord missing, Atlantic Ocean Plateaus of the Atlantic Ocean Marine geology Telegraphy