| A | B |
|---|
| Mid-Ocean Ridge | an undersea mountain chain where new ocean floor is produced; a constructive plate boundary |
| Ocean-floor spreading | the proccess ion which old ocean floor os pushed away from a midocean ridge by the formation of new |
| Trenches | a v-shaped valley on the ocean floor where old ocean floor is subducted, a destructive plate boudary |
| Lithospere | the topmost solid part of the Earth, which is composed of the crust and some of the mantle. |
| Molten Rock | liquified by heat, being in a state of fusion |
| Pangaea | the hypothetical landmass that existed when all continents were joined |
| Fault | section of strata displaced by a earthquake |
| Mantle | portion of the Earth |
| Richter Scale | a logarithmic scale, ranging from 1-10 for indicating intesity of an earthquake |
| Seismograph | any of a various instruments for measuring and recording the vibrations and earthquakes |
