kb/data/en.wikipedia.org/wiki/Mid-ocean_ridge-2.md

title	chunk	source	category	tags	date_saved	instance
Mid-ocean ridge	3/3	https://en.wikipedia.org/wiki/Mid-ocean_ridge	reference	science, encyclopedia	2026-05-05T07:35:39.450676+00:00	kb-cron

The first indications that a ridge bisects the Atlantic Ocean basin came from the results of the British Challenger expedition in the nineteenth century. Soundings from lines dropped to the seafloor were analyzed by oceanographers Matthew Fontaine Maury and Charles Wyville Thomson and revealed a prominent rise in the seafloor that ran down the Atlantic basin from north to south. Sonar echo sounders confirmed this in the early twentieth century. It was not until after World War II, when the ocean floor was surveyed in more detail, that the full extent of mid-ocean ridges became known. The Vema, a ship of the Lamont–Doherty Earth Observatory of Columbia University, traversed the Atlantic Ocean, recording echo sounder data on the depth of the ocean floor. A team led by Marie Tharp and Bruce Heezen concluded that there was an enormous mountain chain with a rift valley at its crest, running up the middle of the Atlantic Ocean. Scientists named it the 'Mid-Atlantic Ridge'. Other research showed that the ridge crest was seismically active and fresh lavas were found in the rift valley. Also, crustal heat flow was higher here than elsewhere in the Atlantic Ocean basin. At first, the ridge was thought to be a feature specific to the Atlantic Ocean. However, as surveys of the ocean floor continued around the world, it was discovered that every ocean contains parts of the mid-ocean ridge system. The German Meteor expedition traced the mid-ocean ridge from the South Atlantic into the Indian Ocean early in the twentieth century. Although the first-discovered section of the ridge system runs down the middle of the Atlantic Ocean, it was found that most mid-ocean ridges are located away from the center of other ocean basins.

=== Impact of discovery: seafloor spreading === Alfred Wegener proposed the theory of continental drift in 1912. He stated: "the Mid-Atlantic Ridge ... zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth". However, Wegener did not pursue this observation in his later works and his theory was dismissed by geologists because there was no mechanism to explain how continents could plow through ocean crust, and the theory became largely forgotten. Following the discovery of the worldwide extent 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 discovered and began to propose mechanisms for seafloor spreading. The discovery of mid-ocean ridges and the process of seafloor spreading allowed for Wegener's theory to be expanded so that it included the movement of oceanic crust as well as the continents. Plate tectonics was a suitable explanation for seafloor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a major paradigm shift in geological thinking. It is estimated that along Earth's mid-ocean ridges every year 2.7 km2 (1.0 mi2) of new seafloor is formed by this process. With a crustal thickness of 7 km (4.3 mi), this amounts to about 19 km3 (4.6 mi3) of new ocean crust formed every year.

== List of mid-ocean ridges ==

Aden Ridge – Rift portion in Gulf of Aden Cocos Ridge – Aseismic ridge within the Cocos plate Explorer Ridge – Mid-ocean ridge west of British Columbia, Canada Cocos–Nazca spreading centre – Spreading centre under central eastern Pacific Ocean Galápagos spreading centre – Western part of the Cocos–Nazca spreading centre Gorda Ridge – Tectonic spreading center off the northern coast of California and southern Oregon Juan de Fuca Ridge – Divergent plate boundary off the coast of the Pacific Northwest region of North America South American–Antarctic Ridge – Mid-ocean ridge in the South Atlantic Chile Rise – Submarine oceanic ridge in the Pacific OceanPages displaying short descriptions of redirect targets East Pacific Rise – Ridge on the floor of the Pacific Ocean Gakkel Ridge – Mid-oceanic ridge under the Arctic Ocean (Mid-Arctic Ridge) Pacific-Antarctic Ridge – Tectonic plate boundary in the South Pacific OceanPages displaying short descriptions of redirect targets Central Indian Ridge – North-south-trending mid-ocean ridge in the western Indian Ocean Carlsberg Ridge – Tectonic plate ridge Southeast Indian Ridge – Mid-ocean ridge in the southern Indian Ocean Southwest Indian Ridge – Mid-ocean ridge in the Indian and Atlantic Oceans Mid-Atlantic Ridge – Atlantic Ocean tectonic plate boundary Kolbeinsey Ridge – Segment of the Mid-Atlantic Ridge north of Iceland in the Arctic Ocean Mohns Ridge – Geographical region in the Atlantic basin Knipovich – Russian zoologistPages displaying short descriptions of redirect targets Ridge (between Greenland and Spitsbergen) Reykjanes Ridge – Atlantic Ocean tectonic plate boundaryPages displaying short descriptions of redirect targets (south of Iceland)

=== List of ancient oceanic ridges === Aegir Ridge – Extinct mid-ocean ridge in the far-northern Atlantic Ocean Alpha Ridge – Major volcanic ridge under the Arctic Ocean Galápagos Rise – Fossil divergent boundary Kula-Farallon Ridge – Ancient mid-ocean ridgePages displaying short descriptions of redirect targets Mid-Labrador Ridge – Mid-ocean ridge in the Labrador Sea Pacific-Farallon Ridge – Spreading ridge during the Late CretaceousPages displaying short descriptions of redirect targets Pacific-Kula Ridge – Former mid-ocean ridgePages displaying short descriptions of redirect targets Phoenix Ridge – Ancient mid-ocean ridge between the Phoenix and Pacific platesPages displaying short descriptions of redirect targets

== See also ==

Afar Triangle – Geological depression caused by the Afar triple junction Aseismic ridge – Geologic feature below some oceans Geography of Iceland List of oceanic landforms Ocean chemistry Oceanic crust Petrological Database of the Ocean Floor Project FAMOUS – first crewed submersible study of the rift valley of the Mid-Atlantic Ridge RISE project – discovery of black smokers hydrothermal systems on the East Pacific Rise Slab window – Type of gap in a subducted oceanic plate Submarine volcano – Underwater vents or fissures in the Earth's surface from which magma can erupt Vine-Matthews-Morely hypothesis; explains relation of marine magnetic anomalies to seafloor spreading.

== References ==

== External links ==

An explanation of relevant tectonic forces Mid-Oceanic ridge, like baseball seam (The Dynamic Earth, USGS) Ridge2000, Studying Mid-Ocean Ridges from Mantle to Microbe