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chapter 17 es vocab
Term | Definition |
---|---|
continental drift | proposed that Earth's continents had once been joined as a single landmass that broke apart and sent the continents adrift. |
pangaea | a greek word that means all the earth. |
magnetometer | a device that can detect small changes in magnetic fields. |
magnetica reversal | happens when the flow in the outer core changes, and Earth's magnetic field changes direction. |
Paleomagnetism | the study of the history of earth's magnetic field. |
isochron | an imaginary line on a map that shows points that have the same age |
seafloor spreading | the theory that explains how new ocean crust is formed at ocean ridges and destroyed at deep-sea trenches |
tectonic plates | huge pieces of crust and rigid upper mantle that fit together at their edges to cover Earth's surface |
divergent boundaries | regions where two tectonic plates are moving apart |
rift valley | when continental crust begins to separate the stretched crust forms a long narrow depression |
convergent boundaries | two tectonic plates are moving toward each other |
subduction | when two plates collide, the denser plate eventually descends below the other, less- dense plate |
transform boundary | a region where two plates slide horizontally past each other |
ridge push | as the older portion of the seafloor sinks, the weight of the uplifted ridge is thought to push the oceanic plate toward the trench formed at the subduction zone |
slab pull | the weight of a subduction plate pulls the trailing slab into the subduction zone much like a tablecloth slipping off the can pull articles off with it. |