subject: Plate Tectonics And Sea-floor Spreading [print this page] The concept of plate tectonics describes the motions from the lithosphere, the comparatively rigid external layer from the Earth that consists of every one of the crust.
and element from the underlying mantle. The lithosphere is divided in to a amount of dozen plates of different sizes and shapes, in common the plates are in movement with respect to one another. A mid-ocean ridge could possibly be considered a boundary between plates in which new lithosphere substance is injected from bellows. since the plates diverge from the mid-ocean ridge they slide on the even more yielding.
layer on the bottom from the lithosphere. Since the sizing from the Earth is essentially constant, new lithosphere could possibly be made on the mid-ocean ridges only if an identical amount of lithosphere substance is consumed elsewhere. The website of the destruction can be an even more type of plate boundary: a seduction zone. There one plate dives below the borders of an even more and is also reincorporated to the mantle. equally sorts of plate boundary are associated to fault systems, earthquakes and volcanism, however the sorts of geologic activity observed on the two limitations are relatively different.
The believed of sea-floor spreading in reality preceded the concept of plate tectonics. In its genuine version, within your earlier 1960's, it described the development and destruction from the ocean floor, however it do not specify rigid lithosphere plates. The hypothesis was substantiated shortly afterward over the discovery that periodic reversals from the Earth's magnetic area are recorded within your oceanic crust. As magma rises below the mid-ocean ridge, ferromagnetic mineral deposits within your magma turn into magnetized within your path from the geomagnetic field. Once the magma cools and solidifies, the path as well as the polarity from the area is preserved within your magnetized volcanic rock. Reversals from the area give increase to some sequence of magnetic.
stripes operating parallel toward the axis from the rift. The oceanic crust so serves like a magnetic tape documenting from the backdrop from the geomagnetic area that could possibly be dated independently; the width from the stripes shows the price from the sea-floor spreading.
