GWBN+1.5

Section 1.5

Vocabulary

 * plate**- separate sections of the lithosphere


 * scientific theory-** a well-tested that explains a wide range of observations


 * plate techtonic** -the geological theory that states that pieces of Earth's lithisphere are in constant slow motion, driven by convection currents in the mantle


 * transfer boundary**-a place where two plates slip past eachother, moving in opposite directions


 * divergent boundary**-the place where two plates move apart


 * rift valley**-a deep valley


 * convergent boundary**-the place where two plates come together

Outline
T=The Theory of Plate Techtonics

-Earth's lithosphere broken into pieces separated by jagged cracks -J.Tuso Wilson discovered that lithosphere is broken into separate sections called plates -plates carry continents, or parts of the ocean floor, or both
 * Summary**

-Wilson combined knowledge of sea-floor spreading, Earth's plates, and continental drift into one theory, the theory of plate tectonics -plates of lithosphere float on top of asthenosphere -convection currents rise in asthenosphere and spread beneath lithosphere, flow of currents causes movemaent of plates -as they move they collide, pull apart, grind past each other causes volcanoes, mountain ranges, and deep-sea trenches to form
 * A Theory of Plate Motion**

-edges of plates meet at lines called plate boundaries, extend deep into lithosphere -faults form along boundaries -three kinds of plate boundaries, transform boundaries, divergent boundaries, and convergent boundaries -transform boundary is where two plates slip past each other, moving in opposite directions -divergent boundaries are the place where two plates move apart, or diverge -most occur in mid-ocean ridge -when divergent boundary occurs in land rift valley forms along divergent boundary, someday rift might split apart -convergent boundary is where two plates come together, or converge -different kinds of convergent boundaries
 * Plate Boundaries**

-plates move one to ten centimeters per year -260 million years ago continents were joined together ina single land mass called Pangaea -225 million years ago Pangaea began to break apart
 * The Continents' Slow Dance**