1. Andrew Lisbon April 4/29/2014 Mr. Mendiola’s class

2.  The very large area of land that existed as the only land on Earth about 300-225 million years ago, before it broke apart to form two large land masses, called Laragia and Gondwanaland.

3.  The gradual movement of the continents across the earth's surface through geological time.

4.  A theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates that move slowly over the underlying mantle.

5.  A large section of Earth’s oceanic or continental crust and rigid upper mantle that moves around on he asthenosphere.

6.  Hess’s theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge.

7.  This rigid layer is about 100km thick and general is less dense than material underneath the plastic like layer below the lithosphere called asthenosphere.

8.  The rigid plates of the lithosphere float and move around on the asthenosphere.

9.  When continental plates pull apart, they can form rift valley. The African continent is separating now along the East African Rift Valley.

10.  Where oceanic and continental plates collide, the oceanic plate plunges beneath the less dense continental plate. As the plate descends, molten rock (yellow) forms and rise toward the surface, creating volcanoes.

11.  A mid-ocean ridge, like the Mid-Atlantic Ridge, forms where oceanic plates continue to separates. As rising magma (yellow) cools, it forms new oceanic crust.

12.  Where two continental plates collide, they push up the crust to form mountain ranges such as the Himalaya.

13.  A version of this same process, occurring, in the mantle, is thought to be the force behind plate tectonics.