The Theory of Plate Tectonics

In the 1960’s evidence supporting the hypotheses of continental drift or seafloor spreading led to the formulation of a theory of plate tectonics moving or pushing up against each other. This causes mountains, terrain change and ocean water to heat up. The earth’s crust consist of two types-oceanic crust and continental crust.

The characteristics of geologic activities are divergent boundaries are when two plates move apart form each other. As the plate moves apart, the asthenosphere flows upward to fill the open space.The decreased pressure causes the asthenosphere to partiallly melt. As it melts it separates form the solid rock and rises to the surface to form new oceanic lithosphere.Most divergent boundaries are found on the ocean floor.

Convergent boundaries The direct collision of one plate with another makes another type of plate boundary a convergent boundary.Three types of of collisions can occur,the oceanic crust at its leading edge. Collides with a plate with continental crust.Oceanic crust denser and it is subducted witch means being forced under less dense continental crust. When one plate moves under another plate it is referred to as subduction zone. A second type of collision occurs when two plates with continental crust at their leading edges come together.The colliding edges are are crumpled and uplifted, causing mountains.

Transform boundaries-A plate boundary called a transform boundary forms where two plates are grinding past each other. They move in sudden spurts and then little or no motion.

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