| A | B |
|---|
| Pangaea | super continent that existed 200 million years ago |
| continental drift | the continents had once been joined as a single landmass that broke apart |
| Alfred Wegener | scientist who thought that the continents were once one super continent |
| ocean ridge | large underwater mountain range |
| seafloor spreading | the theory that explains how new ocean crust is being formed at ocean ridges and destroyed at deep-sea trenches |
| Isochron | imaginary line on a map that shows points that have the same age |
| lithosphere | crust and upper mantle |
| oceanic crust | densest crust |
| magnetometer | device that can detect small changes in magnetic fields |
| sonar | uses sound waves to measure distance |
| near ocean ridges | youngest rock found here |
| far from ocean ridges | oldest rocks found here |
| paleomagnetism | study of Earth;s magnetic field |
| continental-continental boundary | when two continental plates collide |
| continental drift | theory that the continents move |
| divergent boundary | boundary between two plates that are moving apart |
| convergent boundary | boundary where two plates are moving toward each other |
| transform fault boundary | boundary where two plates are moving past each other horizontally |
| convection current | cycle of heating, rising, cooling and sinking |
| subduction zone | area where a dense plate sinks under a less dense plate |
| San Andreas Fault | example of a transform boundary |
| Mid-Atlantic Ridge | example of a divergent boundary in ocean crust |
| oceanic-continental boundary | a dense oceanic plate meets with a continental plate, the denser oceanic plate is subducted |
| Marianas trench | deepest spot in any ocean, an example of converging oceanic plates |
| oceanic-oceanic boundary | a dense oceanic plate descends below another oceanic plate creating an ocean trench. |
