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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 |