The Bermuda Pedestal is an oval geological feature in the northern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

containing the topographic highs of the Bermuda Platform, the Plantagenet (Argus) Bank, and the Challenger Bank. The pedestal is long and wide at the 100 fathom line (-185 m), while the base measures 130 km by 80 km at -4200 m. Surrounding the pedestal is a much larger mid-basin swell known as the Bermuda Rise, measuring 900 km by 600 km at the 5000 m depth contour. The islands of

Bermuda Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest. Bermuda is an ...

are located on the southeastern margin of the Bermuda Pedestal. The

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 ...

surrounding the Bermuda has an age of about 120 Ma, while the initial uplift of the Bermuda Rise occurred in the Middle to

Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

Erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

continued from that time until the

Early Oligocene The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

Volcaniclastic Volcaniclastics are geologic materials composed of broken fragments (clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it ...

deposition and erosion ended with

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...

below sea level in the

Late Oligocene The Chattian is, in the geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the pro ...

. Volcanic basement is at a depth of 75 m across the platform, and 50 m on the island, except for a highpoint near Castle Harbour, at a depth of 15 m. These volcanics consist of tholeiitic lavas and intrusive lamprophyric sheets. Scientists have long considered the Bermuda Pedestal to be the remains of a large extinct

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 ...

that formed between 45 and 35 million years ago. A number of theories have been established to explain the origin of the Bermuda Pedestal. According to one of these theories, it was formed by the volcanic activity of the Bermuda hotspot. In contrast, Peter R. Vogt and Woo-Yeol Jung propose instead that the Bermuda Pedestal possibly formed as a result of a worldwide reorganization of the Earth's tectonic plates due to the closing of the

Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...

when the

Indian subcontinent The Indian subcontinent is a physiographic region of Asia below the Himalayas which projects into the Indian Ocean between the Bay of Bengal to the east and the Arabian Sea to the west. It is now divided between Bangladesh, India, and Pakista ...

collided with

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

. The size of the Bermuda Pedestal combined with knowledge of other mid-ocean volcanoes (immediately north-eastward of the Bermuda Pedestal is the

Bowditch Seamount Bowditch may refer to: Books *''Bowditch's American Practical Navigator'', an encyclopedia of navigation People *Ben Bowditch (born 1984), English footballer * Brian Bowditch (born 1961), British mathematician * Charles Pickering Bowditch (1842 � ...

and a scattering of other seamounts, including Nashville Seamount at the eastern end of the

New England Seamounts The New England Seamounts is a chain of over twenty underwater extinct volcanic mountains known as seamounts. This chain is located off the coast of Massachusetts in the Atlantic Ocean and extends over from the edge of Georges Bank. Many of th ...

, together forming the Bermuda-New England Seamount Arc) tells us that the Bermuda volcano originally reached above sea level and that it took three to ten million years to reduce it to sea level.

References

{{Coord, 32, 20, N, 64, 45, W, display=title Volcanoes of Bermuda Polygenetic shield volcanoes Eocene volcanoes Eocene North America

See also

References