| A | B |
|---|
| Plate Tectonics | The theory that explains how large pieces of the lithosphere, called plates, move and change shape |
| Scientific Theory | A system of ideas that EXPLAINS many related observations and is supported by a large body of evidence acquired through scientific investigation |
| Continental Drift | The hypothesis that a single large landmass broke up into smaller landmasses to form the continents, which |
| Pangaea | The supercontinent that formed 300 million years ago and that began to break up 200 million years ago |
| Continental Crust | This crust is thicker and less dense than oceanic. |
| Oceanic Crust | Earths crust located under the ocean that is usually thinner but more dense than continental crust |
| Subduction Zone | Boundaries where one plate sinks beneath another plate |
| Volcanoes | A vent or fissure in Earth's surface through which magma and gases are expelled |
| Convection Currents | Any movement of matter that results from differences in density; may be vertical, circular, or cyclical |
| Magma | The molten or partially molten rock material containing trapped gases produced under the Earth's surface |
| Lava | Magma that flows onto Earth's surface; the rock that forms when lava cools and solidifies |
| Convergent Boundary | The boundary between tectonic plates that are colliding |
| Divergent Boundary | The boundary between two tectonic plates that are moving away from each other |
| Transform Boundary | The boundary between tectonic plates that are sliding past each other horizontally |
| Fault | A break in a body of rock along which one block moves relative to another |
| Earthquakes | A movement or trembling of the ground that is caused by a sudden release of energy when rocks along a fault move |
| Mid-ocean Ridges | A long, undersea mountain chain that forms along the floor of the major oceans |
| tectonic plates | Sections of the Earth's crust that move due to convection currents. |
| Density | mass/volume |
| Lithosphere | A rigid layer made up of the uppermost part of the mantle and the crust. Consists of the moving earth plates. |
| ocean trench | A steep, long depression in the deep-sea floor that runs parallel to a chain of volcanic islands or a continental margin |
| rift valley | A deep valley that forms where two plates move apart, new crust is made here |
| Asthenosphere | The soft layer of the mantle on which the tectonic plates move |
| Heat Flow in the Earth | Heat is convected out of the core then conducted through the mantle then convected to the plates (lithosphere) |
| Alfred Wegener | German meteorologist who developed the idea of continental drift |
