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The Pacific Plate slides north-northwestward past the North American Plate along the San Andreas Transform Plate Boundary. The San Andreas Fault is responsible for most of the movement in western California, causing a sliver of the state to slide past the rest of the continent.
- Plate Tectonics and Our National Parks
Shaded relief map of the U.S. highlighting different...
- Plate Tectonics and Our National Parks
oceanic crust, the outermost layer of Earth’s lithosphere that is found under the oceans and formed at spreading centres on oceanic ridges, which occur at divergent plate boundaries. Oceanic crust is about 6 km (4 miles) thick. It is composed of several layers, not including the overlying sediment.
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust , composed of troctolite , gabbro and ultramafic cumulates .
24 Απρ 2024 · The age of the oceanic crust has been determined by systematic mapping variations in the strength of the Earth’s magnetic field across the sea floor and comparing the results with our understanding of the record of Earth’s magnetic field reversal chronology for the past few hundred million years.
Divergent boundaries are spreading boundaries, where new oceanic crust is created to fill in the space as the plates move apart. Most divergent boundaries are located along mid-ocean oceanic ridges (although some are on land).
When a continental plate meets an oceanic plate, the thinner, denser, and more flexible oceanic plate sinks beneath the thicker, more rigid continental plate. This is called subduction. Subduction causes deep ocean trenches to form, such as the one along the west coast of South America.
The crust thinned and "collapsed," forming an immense geologic "bowl." Sand, silt and clay from the sea and ancient rivers poured into the bowl. Microorganisms also poured into this hole, piling high in huge layers. These layers would eventually become the oilfields of Los Angeles.