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why do plates move over the surface of the earth

How Do Plates Move? Plates at our planets surface move because heat in the Earths causes molten rock in the mantle layer to flow. We used to think the
just surfed on top of the moving mantle, but now scientists believe that plates help themselves to move. How can plates help themselves move instead of just surfing along? Just like convection cells, plates have warmer, thinner parts that rise, and colder, denser parts that sink. New parts of a plate rise because they are warm and thin, pushing the rest of a plate out of its way at.


Old parts of a plate sink down into the mantle at because they are colder and thicker than the warm mantle underneath them. The mechanism by which tectonic plates move is still a subject of much debate among Earth scientists. The Earth is dynamic thanks to its internal heat, which comes from deep within the mantle from the breakdown of radioactive isotopes. This causes convection in the mantle hot rocks rise and cold rocks descend.


This very slow motion in the solid state transfers stresses to the lithosphere, just as convection in a boiling pan of thick soup will cause the skin to buckle where the convection cells meet. As the theory of plate tectonics developed, mantle convection was long thought to be responsible for the movement of tectonic plates across the Earth s surface. This theory is now largely out of favour, with modern imaging techniques unable to identify convection cells in the mantle sufficiently large to drive plate movement.


Instead, it is thought to be caused by ' slab pull '. Newly formed oceanic lithosphere at mid ocean ridges is less dense than the asthenosphere, but becomes denser with age as it cools and thickens. This causes it to sink into the mantle at subduction zones, pulling slabs of lithosphere apart at divergent boundaries and resulting in sea floor spreading or rifting. How plate movement operates in detail, however, is highly controversial.

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