Question | Answer |
Continental Drift | Alfred Wegener's hypothesis that continents have moved slowly to their current locations. |
Pangea | The giant landmass where all the continents were connected. |
Seafloor Spreading | Harry Hess's theory that was created to help explain why there are mid-ociean ridges. |
Plate Tectonics | The theory that Earth's crust and upper mantle are broken into sections. |
Plate | These sections move on the upper layer of the mantle. |
Lithosphere | The plates and the upper mantle. |
Asthenosphere | The plasticlike layer below the lithosphere. |
Convection Current | The cycle of heating, rising, cooling, and sinking of material that is thought to be the force behind plate tectonics. |
Earthquake | Sudden movements along plate boundaries or faults. |
Primary Waves | The first seismec waves caused by earthquakes, about 2 times faster than secondary waves. |
Secondary Waves | The seismec waves that come after the primary waves, much slower and weaker that primary waves. |
Surface Waves | Seismec Waves that reach to the surface. |
Epicenter | The area right above the focuse of an earthquake on the surface. |
Seismograph | A special device that measures the strength and size of earthquakes with a pendulum, drum of paper, and a pen. |
Volcano | An opening in the Earth that erupts gases, ash, and lava. |
Vent | The opening where the material can escape. |
Crater | The area around the vent that has been formed by cooling lava. |
Hot Spot | Places between the mantle and core that are unusually hot. Hot rock is forced toward the crust at these areas where it partially melts. |
Shield Volcano | A broad volcano with gently sloping sides formed by the build up of flat layeres. Has quiet eruptions. |
Cindercone Volcano | A steeply sided volcano formed by loose material such as tephra. Has violent eruptions. |
Composite Volcano | Volcano with quiet and violent eruptions. Has alternate layers of tephra and lava. |
Tephra | Bits of rock or solidified lava that is dropped from the air. |