GS 16 Convection

a type of heat transfer where materials that are warmed become less dense and rise, and materials that are cooler become more dense and sink

what is convection?

density decreases as materials are warmed

what happens to the density of materials that are warmed?

density increases as materials are cooled

what happens to the density of materials that are cooled?

rock rises/moves upward as it becomes less dense

what happens to rock when it becomes less dense?

rock sinks/moves downward as it becomes more dense

what happens to rock when it becomes more dense?

heat from the core powers convection currents

where does the heat come from that powers earth's convection currents?

convection primarily occurs in the mantle

in what earth layer (crust, mantle, core) does convection primarily occur?

the core's heat comes from (1) radioactive decay and (2) residual heat left over from the formation of the earth

where does the core's heat comes from?

ridge push

what is another name for seafloor spreading?

slab pull

what is another name for subduction?

rock gets older, colder, and more dense as you get further away from a MOR

how does the age, temperature and density of rock change as you get further away from a MOR?

rock gets younger, warmer, and less dense as you get closer to a MOR

how does the age, temperature and density of rock change as you get closer to a MOR?

warmer, less dense rock rises and erupts at a mid ocean ridge, and then sinks as it moves farther away from the ridge and cools

how does convection occur at a mid ocean ridge?

cooler, denser rock sinks at a subduction zone, and then rises as it becomes warmed and erupts out of a volcano

how does convection occur at a subduction zone?

the driving force behind plate tectonics is convection in the upper mantle (asthenosphere)

what is the driving force behind plate tectonics?

because the molecules they are made of begin to move faster and farther apart

why do things that are warmed become less dense?

because the molecules they are made of begin to move slower and closer together

why do things that are cooled become more dense?

oceanic crust gets thicker the farther away you get from a mid ocean ridge

how does the thickness of oceanic crust change as you get further away from a mid ocean ridge?

oceanic crust gets thinner the closer you get to a mid ocean ridge

how does the thickness of oceanic crust change as you get closer to a mid ocean ridge?

cool rock moves down and away at a convergent boundary, and rises once it is warmed again

how does convection occur at a convergent boundary?

warm rock rises and spreads outwards at a divergent boundary, and sinks once it is cooled again

how does convection occur at a divergent boundary?

the asthenosphere is a semi-solid layer, possessing characteristics of both solids and liquids

what is the asthenosphere like?