| A | B |
|---|
| magma | liquid rock beneath the earth surface |
| lava | liquid rock that reaches the earth surface |
| moho | boundary between the crust and mantle |
| lithosphere | the crust and upper mantle |
| mid-ocean ridge | mountain chain running along the middle of an ocean |
| asthenosphere | region of mantle in which convection cells occur |
| P waves | fastest moving (compression) seismic waves-pass thru solids, liquids and gases |
| S waves | transverse (shear) seismic waves-can not travel thru liquids |
| earthquake | violent movement within the earth's crust |
| epicenter | point on earth's surface directly above earthquake focus |
| focus | point within the earth at which an earthquake originates |
| fault | break in earth's crust along which motion occurs |
| tectonic plates | large pieces of the earths lithosphere |
| seismograph | instrument which detects and records earthquake waves |
| outer core | a liquid zone in the Earth; S-waves do not pass thru it |
| inner core | central portion of the Earth's core-highest density and temperatures are here |
| continental crust | rock on the continents-mostly granitic and thicker than oceanic crust |
| oceanic crust | rock on ocean floor-mostly basaltic and thinner than continental crust |
| ocean trench | an ocean floor depression marking zone where crust has subducted |
| ocean floor spreading | theory that new oceanic crust is being produced at mid ocean ridges |
| subsidence | the gradual sinking of a portion of the Earth's crust |
| uplift | the rising of the Earth's crust from forces within the Earth |
| crust | the thin, outermost layer of the solid Earth |
| mantle | the portion of the Earth below the crust and above the core |
