The Theory of Plate Tectonics Ch. 1.5 Plate Tectonics Rap http://www.youtube.com/watch?v=dkELENdZukI

Introduction Plates = large sections of the Earth’s lithosphere Scientific theory = A well tested concept that explains a wide range of observations  

I. How Plates Move A. Plate tectonics = pieces of Earth’s lithosphere are in slow, constant motion, driven by convection currents in the mantle B. The theory of plate tectonics explains the _formation_, _movement_and _subduction_ of Earth’s plates.

C. Geologists think that movement of _convection__ _currents__ in the mantle is the major force that causes plate motion. D. As plates move they collide_, Pull apart or slip__ past each other to cause changes in Earth’s surface.

II. Plate Boundaries A. Faults = breaks in Earth’s crust where rocks slip past each other   B. 3 types of boundaries = _divergent__, __convergent_ and _transform_. Plate Tectonics Video http://www.youtube.com/watch?v=48byqqhviqg

Plate Movement C. Plates move from _1_ to 24_ cm per year. D. N America and Eurasian plates are moving apart _2.5_ cm per year.

E. Divergent Boundaries 1. divergent = the place where two plates move apart 2. most occur along _mid_-_ocean_ _ridges_ 3. rift valley = a deep valley forms along a divergent boundary Brain Pop Plate Tectonics

Great Rift Valley

F. Convergent Boundaries 1. convergent = place where 2 plates come together 2. Where two plates carrying _oceanic_crust meet at a trench, the plate that is more _dense_ sinks_ _under the other plate. 3. Subduction occurs as the oceanic plate _sinks__ _beneath_the continental plate. 4. The collision between two continental crust plates squeezes the crust into mighty _mountain_ _ranges_. Brain Pop Mountains

The Andes mountains, which span the entire western coast of South America, formed when the Nazca plate subducted under the South American plate.

G. Transform Boundaries 1. transform = 2 plates slip past each other in opposite directions 2. Earthquakes often occur along transform boundaries, but crust is neither __created__ nor _destroyed_.

San Andres Fault (California)

III. Plate Motion Over Time A. . The movement of the _Earth’s plates___ has greatly changed _Earth’s __ _surface_. B. _Continental__ _drift_ has taken the continents about 225 million years since the breakup of Pangaea to get to their present location. Earth Boundaries 100 Million Years from Now http://www.youtube.com/watch?v=uGcDed4xVD4