| A | B |
|---|
| mid-ocean ridge | largest under sea mountain range where new ocean floor is produced |
| transform boundary | 2 plates move past each other in opposite directions |
| sonar | a device determining the distance of an object under water & records sound waves |
| plate | a slowly moving section of lithosphere carrying pieces of continental and oceanic crust |
| divergent boundary | 2 plates move away from each other |
| rift valley | deep valley forming where 2 plates move apart |
| fault | break in Earth's crust where slabs of rock move past each other |
| sea-floor spreading | a process where molten material adds new oceanic crust |
| deep-ocean trench | deep valley along ocean floor where oceanic crust sinks towards mantle |
| plate tectonics | a theory that pieces of lithosphere in constant motion due to convection currents in mantle |
| scientific theory | well-tested concept |
| convergent boundary | 2 plates move toward each other |
