| A | B |
|---|
| Sea Floor Spreading | The process by which molten material adds new oceanic crust to the ocean floor |
| Sonar | A device that determines the distance of an object under water by recording echoes of sound waves |
| Deep Ocean Trench | A deep valley along the ocean floor through which oceanic crust slowly sinks towards the mantle |
| Mid Ocean Ridge | The undersea mountain cvhain where new ocean floor is produced, a divergent plate boundary |
| Subduction | The process by which oceanic crust sinks beneath a deep-ocean trnch and back into the matle at a convergent plate boundary |
| What happens in subduction? | The ocean floor sinks back to the mantle beneath deep ocean trenches |
| What happens in sea-floor spreading? | molten material erupts along the mid-ocean ridge and hardens to form rock. |
| Describe plate tectonics | Plates slip past each other at transform boundaries, move apart at divergent boundaries, and come together at convergent boundaries |
| What does the theory of plate tectonics explain? | How plate movement causes continental drift and sea-floor spreading |
