| A | B |
|---|
| Theory of Continental Drift | The Earth once had a single landmass that broke up into large pieces, which have since drifted apart. |
| Alfred Wegner | Had the theory of Continental drift. |
| Pangaea | All Earth. (When all of the continents were formed as one). |
| Convection curents | A movement of material caused by differences in temperature. |
| Glossopteris | Fossils located in frocks about 250 million years old. It is an extinct plant. These fossils are found in South Africa, Australia, India, and Antarctica. |
| Ocean Floor Spreading | The process in which old ocean floor is pushed away from a midocean ridge by the formation of new ocean floor. |
| Subduction | the process in wich lithosphere plunges into the interior of the earth. |
| Trenches | deep v shaped valleys that lie along the bottom of the ocean floor.they are the deepest part of the ocean. |
| rift valley | a valley formed when a block of land between two normail faults slides downward. |
| Island arcs | Islands formed when two oceanic plates collide the older oceanic plate is subducted under the younger. the plate being subducted melts. Molten rock then rises up and breaks through the surface. As a result a string of Volcanoserupts on the ocean floor along the trench. in time, this string of undersea volcanoes may rise above the oceans surface as a string of islands. |
| midocean ridge | an undersea mountain chain where new ocean floor is produced, a constructive (divergent) plate boundary |
| Plate tectonics | Moving plates. |
