Search results
Results from the WOW.Com Content Network
Continental drift is the scientific theory, originating in the early 20th century, that Earth's continents move or drift relative to each other over geologic time. [1] The theory of continental drift has since been validated and incorporated into the science of plate tectonics, which studies the movement of the continents as they ride on plates of the Earth's lithosphere.
From 1912, Wegener publicly advocated the existence of "continental drift", arguing that all the continents were once joined in a single landmass and had since drifted apart. He supposed that the mechanisms causing the drift might be the centrifugal force of the Earth's rotation ("Polflucht") or the astronomical precession.
Alfred Wegener, being a meteorologist, had proposed tidal forces and centrifugal forces as the main driving mechanisms behind continental drift; however, these forces were considered far too small to cause continental motion as the concept was of continents plowing through oceanic crust. [33]
Polflucht (from German, flight from the poles) is a geophysical concept invoked in 1922 by Alfred Wegener to explain his ideas of continental drift.. The pole-flight force is that component of the centrifugal force during the rotation of the Earth that acts tangentially to the Earth's surface.
The continental crust on the downgoing plate is deeply subducted as part of the downgoing plate during collision, defined as buoyant crust entering a subduction zone. An unknown proportion of subducted continental crust returns to the surface as ultra-high pressure (UHP) metamorphic terranes, which contain metamorphic coesite and/or diamond plus or minus unusual silicon-rich garnets and/or ...
Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere.This type of tectonics is found at divergent plate boundaries, in continental rifts, during and after a period of continental collision caused by the lateral spreading of the thickened crust formed, at releasing bends in strike-slip faults, in back-arc basins, and on the continental end of ...
Earlier theories by Alfred Wegener and Alexander du Toit of continental drift postulated that continents in motion "plowed" through the fixed and immovable seafloor. The idea that the seafloor itself moves and also carries the continents with it as it spreads from a central rift axis was proposed by Harold Hammond Hess from Princeton University and Robert Dietz of the U.S. Naval Electronics ...
The Vine–Matthews–Morley hypothesis, also known as the Morley–Vine–Matthews hypothesis, was the first key scientific test of the seafloor spreading theory of continental drift and plate tectonics. Its key impact was that it allowed the rates of plate motions at mid-ocean ridges to be computed.