| A | B |
|---|
| Hydrosphere | Earth's water environments; lakes, rivers and oceans |
| Atmosphere | The layer of gases that surround Earth. |
| Biosphere | All of the living things found on Earth |
| Lithosphere | The layer of solid rock that forms Earth's outer surface |
| Continents | A great landmass surrounded by oceans |
| Pangaea | The name of the single landmass that broke apart 200 million years ago and gave rise to today's continents |
| Continental Drift | The hypothesis that the continents slowly move across Earth's surface |
| Mid-Ocean Ridge | The undersea mountain chain where new ocean floor is produced; a divergent plate boundary |
| Sea-Floor Spreading | The process by which molten material adds new oceanic crust to the ocean floor |
| Deep-Ocean Trenches | A deep valley along the ocean floor through which oceanic crust slowly sinks toward the mantly |
| Subduction | The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary |
| Plate Tectonics | The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle |
| Faults | A break in Earth's crust where slabs of rock slip past each other |
| Transform Boundary | A plate boundary where two plates move past each other in opposite direction |
| Divergent Boundary | A plate boundary where two plates move away from each other |
| Convergent Boundary | A plate boundary where two plates move toward each other |
