Plate Tectonics Mrs. Chamberlain’s 7 th Grade Science

 The top layer of the Earth's surface is called the crust (it lies on top of the plates).  There is an upper mantle which includes the asthenosphere and a lower mantle.  The crust and the upper mantle are called the lithosphere.  Convection currents (in asthenosphere) drive the motion of the tectonic plates. This occurs due to heat from the core. Boundaries Convection Currents Demonstration

 The Eurasian plate, Australian-Indian plate, Philippine plate, Pacific plate, Juan de Fuca plate, Nazca plate, Cocos plate, North American plate, Caribbean plate, South American plate, African plate, Arabian plate, the Antarctic plate, and the Scotia plate. Pangaea

 In 1915, the German geologist and meteorologist Alfred Wegener ( ) first proposed the theory of continental drift  Continental drift states that parts of the Earth's crust slowly drift atop a liquid core.  The fossil record supports the theories of continental drift and plate tectonics. Layers of the Earth

 Wegener hypothesized that there was an original, gigantic supercontinent 200 million years ago, which he named Pangaea, meaning "All-earth".  Pangaea was a supercontinent consisting of all of Earth's land masses. Continental Drift Bibliography

Plate Boundaries Convergent Boundaries Divergent Boundaries Transform Boundaries (slide) (divide) (collide) Continental Drift Bibliography

 Two plates moving apart from each other  Where the plates move away from each other is called the zone of divergence  Description/Example : Sea-floor spreading (Mid-Atlantic Ridge), Rift valleys (Great Rift Valley)

 When two plates collide.  Description/Examples : cont/cont = mountains; cont/ocean – volcanoes; ocean/ocean – subduction zone (& volcanoes)  Subduction is when an oceanic plate collides with an continental plate and is forced under it.

 When two plates move sideways against each other  Can cause lots of friction and is jerky  Description/Examples : Faulting (cracks and earthquakes); force is shearing

 When two plates collide and one slides under the other the region below is called the subduction zone.  Description/Examples: Cont/ocean – ocean sinks below; ocean/ocean – one sinks; either can form volcano

Bibliography  Earth’s Continental Plates, Continents.shtml Continents.shtml  Continental Drift Picture 1,  Pangaea Picture,