| A | B |
|---|
| fossil | preserved remains or evidence of a living thing |
| Pangaea | single giant landmass that existed more than 200 million years ago and gave rise to the present day continents |
| theory of continental Drift | theory propsed by Alfred Wegener that the continents were once joined together and have since drifted apart |
| midocean ridge | undersea mountain chain where new ocean floor is produced; a constructive plate boundary |
| ocean-floor spreading | process in which old ocean floor is pushed away from a midocean ridge by the formation of new ocean floor |
| transform fault | fault that runs across a midocean ridge |
| trench | V-shpaed valley on the ocean floor where old ocean floor is subducted; a desstrucive plate boundary |
| subduction | process in which crust plunges back into the interior of the Earth |
| theory of plate tectonics | theory that links together the ideas of contitnental drift and ocean floor spreading and explains how the earth has changed over time |
| plate | in plate tectonics, one of the moving irregularly shaped slabs that make up the Earth's lithosphere |
| tectonics | branch of geology that deals with the movements that shape the earth's crust |
| lithosphere | topmost solid part of the Earth, which is composed of the crust and some of the mantle |
| divergent boundary | plate boundary at which plates move apart |
| convergent boundary | plate boundary at which plates come together |
| strike-slip boundary | plate boundary at which two plates slip past each other horizontally |
| convection current | movement of air (or water) caused by cool, dense air (or water) sinking and warm, less dense air (or water) rising; movement of material caused by differences in temperature |
| Wegener's theory is based on... | evidence from fossils and rock formations |
| the ___ of the Earth's landmasses affects their climate | location |
| ocean floor spreading occurs as.... New ocean floor forms as... | parts of the ocean floor move away from a rift valley in the center of a midocean ridge. molten rock rises through the rift and hardens |
| ocean floor is destroyed when... | it is subducted into trenches and melted inside the mantle |
| the ocean floor is made of pieces the move from __ to __ Many of these moving pieces have __ on top of them | rifts, trenches, continents |
| Both the ages of the ocean floor rocks and the magnetic stripes on the ocean floor are evidence of... | ocean floor spreading |
| the theory of plate tectonics, which links together the ideas of..... , explains how the earth evolved over time. it helps to explain the formation and destruction of ___ and it's movements and collisions | continental dift and ocean-floor spreading, Earth's crust |
| the lithosphere, which consists of....., is made of a number of plates | the crust and a thick layer of relatively cool, rigid mantle rock |
| plates usually contain both..... | oceanic and continental crust |
| divergent plate boundaries are formed by... | the trenches |
| strike slip boundaries are formed by.... | lateral faults at which two plates slide horizontally past each other |
| some scientists hypothesize that plate movements is caused by.... | convection currents within the mantle |
| understanding how the plates have moved in the past makes it posssible to.... | predict their future movement |
