| A | B |
|---|
| plate tectonics theory | sections of lithosphere move across a semi-solid asthenosphere |
| continental drift | the earth's land masses have moved from their original locations millions of years ago |
| sea-floor spreading | new molten lava comes out tof the earth at the mid-ocean ridges, expanding the ocean crust |
| inner core | made of solid iron and nickel |
| mantle | thickest , solid rock part of the earth with a plastic-like upper layer |
| crust | found under oceans and continents, thinnest and outermost layer of the earth |
| outer core | composed of liquid iron and nickel |
| asthenosphere | it's taffy-like consistency has allowed plates to slide across it |
| convection currrents | hot air rising and cool air sinking gives the plates the energy to move; happens in this layer of the earth |
| magnetic field | the area around a magnet where the magnetism is felt the strongest |
| attract | when opposite poles of a magnet are near one another they will do this |
| repel | the north pole of a magnet near another north pole of a magnet will do this |
| magnetosphere | the name of the arth's magnetic field |
| compass needle | a bar magnet with a north pointing needle which is really the south pole of a bar magnet |
| plate | one of about 13 large sections of lithosphere which move across the asthenosphere |
| convergent boundaries | where earthquakes occur frequently as plates collide |
| divergent boundaties | where plates are pulling apart, at the mid-ocean ridges |
| seismic waves | energy released in the form of P,Sor L |
| compression waves | p-waves, push/pull along, very fast, move through all substances |
| transverse waves | S-waves or L-waves, slower, side to side |
