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A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system that is part of every ocean, making the mid-oceanic ridge system the longest mountain range in the world, the continuous mountain range is 65,000 km (40,000 miles) long, and the total length of the system is 80,000 km (50,000 miles)[1]. From NASA. This is a rendering of an ocean ridge, copied from http://earthobservatory. ...
Still from NASA movie that shows how ocean ridges are formed, lithosphere subducted at trenches; good for understanding plate tectonics. ...
Lyskamm, 4 527 m, Pennine Alps A mountain is a landform that extends above the surrounding terrain in a limited area. ...
The tectonic plates of the world were mapped in the second half of the 20th century. ...
Animated map exhibiting the worlds oceanic waters. ...
Convection in the most general terms refers to the internal movement of currents within fluids (i. ...
Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ...
The tectonic plates of the world were mapped in the second half of the 20th century. ...
In plate tectonics, a divergent boundary (divergent fault boundary or divergent plate boundary), (but also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. ...
The Himalaya as seen from the International Space Station A mountain range is a group of mountains bordered by lowlands or separated from other mountain ranges by passes or rivers. ...
Description
Mid-ocean ridges are geologically active, with new magma constantly emerging onto the ocean floor and into the crust at and near rifts along the ridge axes. The crystallized magma forms new crust of basalt and gabbro. Basalt Basalt (IPA: ) is a common gray to black volcanic rock. ...
Gabbro specimen. ...
The rocks making up the crust below the sea floor are youngest at the axis of the ridge and age with increasing distance from that axis. New magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earth's mantle. Basalt Basalt (IPA: ) is a common gray to black volcanic rock. ...
Earth cutaway from core to exosphere. ...
The oceanic crust is made up of rocks much younger than the Earth itself: most oceanic crust in the ocean basins is less than 200 million years old. The crust is in a constant state of 'renewal' at the ocean ridges. Moving away from the mid-ocean ridge, ocean depth progressively increases; the greatest depths are in ocean trenches. As the oceanic crust moves away from the ridge axis, the peridotite in the underlying mantle cools and becomes more rigid. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere. Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ...
Categories: Stub | Plate tectonics | Earth sciences | Landforms | Oceanic trenches ...
Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ...
The tectonic plates of the Lithosphere on Earth. ...
Formation processes There are two processes, ridge-push and slab-pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the weight of the ridge pushes the rest of the tectonic plate away from the ridge, often towards a subduction zone. At the subduction zone, "slab-pull" comes into effect. This is simply the weight of the tectonic plate being subducted (pulled) below the overlying plate dragging the rest of the plate along behind it. Categories: Geology stubs | Plate tectonics ...
The other process proposed to contribute to the formation of new oceanic crust at mid-ocean ridges is the "mantle conveyor" (see image). However, there have been some studies which have shown that the upper mantle (asthenosphere) is too plastic (flexible) to generate enough friction to pull the tectonic plate along. Moreover, unlike in the image above, mantle upwelling that causes magma to form beneath the ocean ridges appears to involve only the mantle above about 400 km depth, as deduced from seismic tomography and from studies of the seismic discontinuity at about 400 km. The relatively shallow depths from which the upwelling mantle rises below ridges are more consistent with the "slab-pull" process. Earth cutaway from core to exosphere. ...
Earth cutaway from core to exosphere. ...
Friction is the force that opposes the relative motion or tendency toward such motion of two surfaces in contact. ...
Seismic tomography uses digital seismographic records to image the interior of the Earth. ...
The rate at which the mid-ocean ridge creates new material is known as the spreading rate, and is generally measured in mm/yr. The common subdivisions of spreading rate are fast, medium and slow, whose values are generally >100 mm/yr, ~60 mm/yr, and <20 mm/yr respectively. The spreading rate of the north Atlantic Ocean is 10 mm/yr, while in the Pacific region, it is 40-60 mm/yr.
The mid-ocean ridge systems form new oceanic crust. As crystallized basalt extruded at a ridge axis cools below Curie points of appropriate iron-titanium oxides, magnetic field directions parallel to the Earth's magnetic field are recorded in those oxides. The orientations of the field in the oceanic crust record preserve a record of directions of the Earth's magnetic field with time. Because the field has reversed directions at irregular intervals throughout its history, the pattern of reversals in the ocean crust can be used as an indicator of age. Likewise, the pattern of reversals together with age measurements of the crust is used to help establish the history of the Earth's magnetic field. The Curie point is a term in physics and materials science, named after Pierre Curie (1859-1906), and refers to a characteristic property of a ferromagnetic material. ...
The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ...
The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ...
Discovery Because a mid-ocean ridge is submerged at very deep depths in the ocean, its existence was not even known until the 1950s, when it was discovered through surveys of the ocean floor conducted by research ships. This does not cite its references or sources. ...
More specifically, the Vema, a ship of the Lamont-Doherty Geological Observatory of Columbia University, traversed the Atlantic Ocean, recorded data about the ocean floor from the ocean surface. A team lead by Marie Tharp and Bruce Heezen analyzed the data and concluded that there was an enormous mountain chain running along the middle of the Atlantic. The mountain range was named the Mid-Atlantic Ridge; it remains the most famous part of the mid-ocean ridge. Columbia University is a private research university in the United States. ...
Marie Tharp (July 30, 1920 - ) is a geologist and oceanographic cartographer who, along with her colleague Bruce Heezen, co-discovered the Mid-Oceanic Ridge, a line of undersea mountains that runs through Earths oceans, and mapped the features of the entire ocean floor. ...
Bruce C. Heezen (1924 - June 21, 1977) was a geologist. ...
Courtesy USGS The ridge was central in the breakup of Pangaea that began some 180 million years ago. ...
At first, it was thought to be a phenomenon specific to the Atlantic Ocean, because nothing like such a massively-long undersea mountain chain had ever been discovered before. However, as surveys of the ocean floor continued to be conducted around the world, it was discovered that every ocean contained parts of the mid-ocean ridge.
Impact Alfred Wegener had proposed the theory of continental drift in 1912. However, the theory had been dismissed by geologists because there was no mechanism to explain how continents could plow through ocean crust, and the theory became largely forgotten. Image File history File links Plates_tect2_en. ...
Image File history File links Plates_tect2_en. ...
The tectonic plates of the world were mapped in the second half of the 20th century. ...
Alfred Wegeners theory of continental drift was widely ridiculed in his day Alfred Lothar Wegener (Berlin, November 1, 1880 – Greenland, November 2 or 3, 1930) was a German interdisciplinary scientist and meteorologist, who became famous for his theory of continental drift. ...
Plates in the crust of the earth, according to the plate tectonics theory Continental drift refers to the movement of the Earths continents relative to each other. ...
1912 (MCMXII) was a leap year starting on Monday in the Gregorian calendar (or a leap year starting on Tuesday in the 13-day-slower Julian calendar). ...
the are cool The Geologist by Carl Spitzweg A geologist is a contributor to the science of geology, studying the physical structure and processes of the Earth and planets of the solar system (see planetary geology). ...
Animated, colour-coded map showing the various continents. ...
Earth cutaway from core to exosphere. ...
Following the discovery of the mid-ocean ridge in the 1950s, geologists faced a new task: explaining how such an enormous geological structure could have formed. In the 1960s, geologists began to propose mechanisms of sea floor spreading. Plate tectonics was a direct consequence of sea floor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a major paradigm shift in geological thinking. The 1960s decade refers to the years from January 1, 1960 to December 31, 1969, inclusive. ...
Seafloor spreading is a part of the theory of plate tectonics. ...
The tectonic plates of the world were mapped in the second half of the 20th century. ...
Paradigm shift is the term first used by Thomas Kuhn in his 1962 book The Structure of Scientific Revolutions to describe a change in basic assumptions within the ruling theory of science. ...
List of oceanic ridges The East Pacific Rise is a long north-south welt of seafloor spreading under the eastern Pacific Ocean from near Antarctica in the south northward to its termination at the northern end of the Gulf of California in the Salton Sea basin in southern Pennsylvania California. ...
The Emperor Seamounts are a chain of seamounts (submerged volcanic mountains) extending from the northwestern Hawaiian Islands (see Kure and Midway atolls) in a northwesterly direction until approximately 170º east longitude where they trend abruptly northward towards the tip of the Aleutian Islands and the Kamchatka Peninsula. ...
Category: ...
The Gakkel Ridge is a mid-oceanic ridge located in the Arctic Ocean between Greenland and Siberia with a length of about 1800 kilometers. ...
The Gorda Ridge is a tectonic spreading center located off the coast of Oregon and northern California north of Cape Mendocino. ...
The Juan de Fuca Ridge is a tectonic spreading center located off the coasts of the state of Washington in the United States and the province of British Columbia in Canada. ...
The Kerguelen Plateau is an underwater volcanic ridge—the largest in the Indian Ocean, and one of the largest in the world. ...
Lomonosov Ridge (Хребет ЛомоноÑова in Russian) is an underwater oceanic ridge in the Arctic Ocean. ...
Courtesy USGS The ridge was central in the breakup of Pangaea that began some 180 million years ago. ...
The Pacific-Antarctic Ridge is the southern extension of the East Pacific Rise The Pacific-Antarctic Ridge is an oceanic ridge at the boundary between the Pacific and Antarctic Plates. ...
List of ancient oceanic ridges The Phoenix Ridge (also called the Aluk Ridge) was an ancient mid-ocean ridge that existed between the Phoenix Plate and the Pacific Plate. ...
The Kula Ridge was an ancient mid-oceanic ridge in the Pacific Ocean during the Jurassic period. ...
See also The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. ...
The tectonic plates of the world were mapped in the second half of the 20th century. ...
A landform comprises a geomorphological unit. ...
Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ...
Notes - ^ Cambridge Encyclopedia 2005
External link - An explanation of relevant tectonic forces
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