Question | Answer |
crust | The Earth's outermost layer. |
mantle | The layer directly beneath the Earth's crust. |
core | The Earth's innermost layer. |
lithosphere | The cool, solid portion of Earth that includes all of the crust and part of the upper mantle. |
asthenosphere | A zone of partially melted rock in the upper mantle of the Earth. |
plate tectonics | The theory scientists use to explain the movement of plates on the Earth's surface. |
divergent boundary | A boundary where crustal plates move away from each other. |
convergent boundary | A boundary where crustal plates collide with each other. |
transform fault boundary | A boundary where crustal plates grind past each other. |
mid-ocean ridge | The place where plates of the Earth's crust along the ocean floor are bing split apart and molten rock pushes up to form new ocean floor and a mountain range. |
rift | A deep ocean valley formed where two crustal plates move apart. |
sea-floor spreading | A process in which magma is slowly pushed up through cracks in a rift and then cools to form new sea floor. |
earthquake | The sudden movement of rock along a fault which releases energy vibrations. |
focus | The point in the Earth's crust where the first major movement of an earthquake fault occurs. |
epicenter | The point on the Earth's surface directly above the focus of an earthquake. |
P wave | A primary wave, or "push-pull" wave of released energy in the Earth's surface that causes a back-and-forth vibration in the same direction that the wave moves. |
S wave | A slower kind of energy wave released by an earthquake that causes vibrations at right angles to the waves direction of travel. |
surface wave | An energy wave from an earthquake that travels only at the surface and moves less quickly than P waves and S waves but makes the ground roll and sway. |
Richter scale | A scale that measures the amount of energy released during an earthquake. |
volcano | A mountain that may form around an opening in the Earth's surface where an eruption of molten rock occurs. |