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PLHS Science 9 Unit2
Unit 2 Plate Tectonics
| Term | Definition |
|---|---|
| convergent boundary | when two plates collide with each other |
| divergent boundary | when two plates separate from each other |
| transform boundary | when two plates slide past each other |
| density | how much mass there is in a certain amount of space (D=m/v) |
| trench | a steep sided depression in an ocean floor |
| Island Arc | caused from two oceanic plates colliding, subducting and errupting magma |
| Volcano | a vent in the earth's crust where magma and gas escape |
| earthquake | a sudden, violent shaking of the ground caused by movement of rock within the earth |
| seismic waves | an elastic wave in the earth produced by an earthquake |
| subduction zone | the area where one plate is pulled under another |
| radioactive isotope | an atom with an unstable nucleus, usually from having too many neutrons or protons |
| pangea | a supercontinent comprised of all of today's continents |
| continental drift | theory that continents once formed pangea and are now drifting furter apart |
| radiation | transfer of energy in the form of particles or waves |
| conduction | point by point transfer of energy through a medium |
| convection | movement of gas or liquid where hotter, less dense materials rise and cooler, more dense materials sink |
| Convection current | a current in a fluid caused by convection. hotter things rise and cooler things sink |
| asthenosphere | a hot, semi-liquid zone on which tectonic plates float |
| lithosphere | rigid outer layer of the earth broken up into tectonic plates |
| mid-ocean ridge | a ridge in the ocean formed by divergent plates spreading apart and magma pushing through the rift |
| sonar | a system for detecting objects under water by sending a pulse and waiting for it to come back |
| sea floor spreading | new layers of oceanic crust formed by divergent plates when magma erupts through the ridges |