Plate Tectonics

Plate tectonics (from the Greek τέκτων; tektōn, meaning "builder" or "mason") describes the large scale motions of Earth's lithosphere. The theory encompasses the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, understood during the 1960s.

Plate Background Info

          Plates are continents and ocean basins, or a variety of the sorts. Plates are filled with mountains, valleys, canyons, etc.

          Tectonic is a Greek word for building, so tectonic plates are like building plates.

          There are about 50 plates, 7 larger ones. They float like slabs of ice on a lake and are about 60 miles thick. It is thought that some planets have plated, like Venus, Mars, and Titan-the largest moon of Saturn.

          There have been many theories about how the plates move. Finally, we came up with a reasonable theory. It was that earth's lithosphere-that consists of large plates that move around in response to the flow of the athenosphere beneath it. The athenoshpere consist of molten magma that constantly flows from the hedges to the center, where it moves. There is also a 'prime movement' theory that plates move because one constantly sets off movement of the other plates. Geologists understand that the continents and the ocean floors are connected and move together. Plates can move over the underlying layer, which is hotter and softer.

          There are three types of plate boundaries: divergent, convergent, and transform fault boundaries.

          Divergent boundaries are where the plates are moving apart and new crust is being created. The old crust melts down, new crust forms when magma breaks the surface.

          Convergent boundaries are where the plates are moving together and crust is being destroyed. The plates may bump; the heavier plate slides under the lighter one. The heavier plate will melt 50 or so miles below Earth's surface. The melted rock will rise slowly, since it is lighter, it melts and pushes to the surface. People think it moves because of radioactive minerals deep inside Earth.

           Transform fault boundaries are where plates slide past one another and can possibly lock.
           Plate boundary zones are areas where plate interactions are complex.

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