Search results
Results from the WOW.Com Content Network
Map showing Earth's principal tectonic plates and their boundaries in detail. These plates comprise the bulk of the continents and the Pacific Ocean.For purposes of this list, a major plate is any plate with an area greater than 20 million km 2 (7.7 million sq mi)
Where the plates meet, their relative motion determines the type of plate boundary (or fault): convergent, divergent, or transform. The relative movement of the plates typically ranges from zero to 10 cm annually. [5] Faults tend to be geologically active, experiencing earthquakes, volcanic activity, mountain-building, and oceanic trench formation.
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.
Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust , or sial , generally less than 10 kilometers thick; however, it is denser, having a mean density of about 3.0 grams per cubic centimeter as opposed to continental crust which has a density of about 2.7 grams ...
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 km 2 (1.0 sq mi) of new seafloor is formed by this process. [50]
The sedimentary rocks of the Basal Complex were deposited on the ocean floor and represent the uppermost part of the oceanic crust that was uplifted and incorporated into the volcanic edifice during volcanic activity. The Mesozoic sedimentary rocks are mostly metamorphosed, and they are steeply tilted. The tilting occurred in the mid-Cretaceous ...
The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone The simplified model of mantle convection: [5] Oceanic plates are subducted creating oceanic trenches. According to the theory of plate tectonics , the Earth's lithosphere , its rigid outer shell, is broken into sixteen larger tectonic plates and several ...
In plate tectonics, the outermost part of the Earth known as the lithosphere (the crust and uppermost mantle) act as a single mechanical layer. The lithosphere is divided into separate "plates" that move relative to each other on the underlying, relatively weak asthenosphere in a process ultimately driven by the continuous loss of heat from the ...