GS16: Convection

lithosphere

solid layer; made up of the crust and the uppermost rigid mantle

asthenosphere

plastic-like layer in Earth's upper mantle that is soft and weak because it is close to melting

convection current

heat makes a fluid (liquid or gas) less dense, so it rises; when it gets further from the heat source it cools, becomes more dense, and sinks back down; this creates a constant cycle (think of a lava lamp)

where convection currents are located in the Earth

asthenosphere (and outer core)

how convection is related to plate tectonics

because the lithosphere is on top of the asthenosphere, the convection currents in the asthenosphere cause the tectonic plates (pieces of lithosphere) to move

Arthur Holmes

proposed the idea (in the early 1930's) that convection currents in the mantle are moving the plates

warm liquids ____ because they are ____ ____

rise; less dense

cool liquids ____ because they are ____ ____

sink; more dense