Search results
Results from the WOW.Com Content Network
Tectonic plates are able to move because of the relative density of oceanic lithosphere and the relative weakness of the asthenosphere. Dissipation of heat from the mantle is the original source of the energy required to drive plate tectonics through convection or large scale upwelling and doming. As a consequence, a powerful source generating ...
Plates that are not subducting are driven by gravity sliding off the elevated mid-ocean ridges a process called ridge push. [4] At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Hydrothermal vents are common at spreading centers. Older rocks will be found farther away from the ...
In 1947, a team of scientists led by Maurice Ewing confirmed the existence of a rise in the central Atlantic Ocean, and found that the floor of the seabed beneath the sediments was chemically and physically different from continental crust. [54] [55] As oceanographers continued to bathymeter the ocean basins, a system of mid-oceanic ridges was ...
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.
With support from the maps of the sea floor, and the recently developed theory of plate tectonics and continental drift, Hess was able to prove that the Earth's mantle continuously released molten rock from the mid-ocean ridge and that the molten rock then solidified, causing the boundary between the two tectonic plates to diverge. [8]
At a seafloor spreading ridge, plates move away from the ridge, which is a topographic high, and the newly formed crust cools as it moves away, increasing its density and contributing to the motion. At a subduction zone the relatively cold, dense oceanic crust sinks down into the mantle, forming the downward convecting limb of a mantle cell ...
Scientists believe they’ve discovered an ancient ocean floor comprising a new layer between Earth’s mantle and core.
The geophysicists were right to state that the Earth is solid, and the mantle is elastic (for seismic waves) and inhomogeneous, and the ocean floor would not allow the movement of the continents. But excluding one alternative, substantiates the opposite alternative: passive continents and an active seafloor spreading and subduction , with ...