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7.2. Plate Tectonics and its manifestations

Plate Tectonics

With the knowledge of the ocean floor (Hess, 1962), the Theory of Plate Tectonics emerged. This theory explains, in a global way, many geological phenomena that until then were thought to be unrelated. Plate tectonics explains what the lithosphere is like, the plates into which it is divided and their movements on the Earth's mantle. It also explains how mountain ranges are formed and why earthquakes and volcanoes are concentrated in certain regions of the planet. Or why the ocean trenches are next to the continents and not in the center of the ocean.

The main postulates of the theory of Plate Tectonics are:

  • The lithosphere, which comprises the crust plus the upper part of the mantle, is fragmented into rigid blocks called lithospheric plates.
  • Lithospheric plates move over a zone of plastic behavior, a zone of low speed of seismic waves where the asthenosphere was previously said to be, although we have already seen that there were controversies about its existence.
  • The thermal energy of the interior of the Earth produces convection currents in the mantle that are capable of dragging the lithospheric plates.
  • The contact zones between lithospheric plates are called plate boundaries or edges. In them most of the internal geological activity (earthquakes and volcanoes) of the Earth takes place.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.