It plays a number of roles. First, the tectonic plates essentially float on the asthenosphere because they are less dense. Second, since oceanic crust is denser than continental crust, it can subduct into the mantle while continental crust cannot. Plate tectonics is driven in part by mantle convection, which results from variations in density due to temperature differences.
they both have density
plate tectonics=D
Volcanoes don't help plate tectonics; volcanoes are the result of plate tectonics.
the crust cracks and magma fills in the space
Nope plate tectonics do not exist on Venus.
they both have density
plate tectonics=D
Volcanoes don't help plate tectonics; volcanoes are the result of plate tectonics.
Plate tectonics
I'd say plate tectonics.
the crust cracks and magma fills in the space
yes plate tectonics are flat
plate tectonics
No plate tectonics on Mars
plate tectonics
Nope plate tectonics do not exist on Venus.
Yes, earthquakes are an affect of plate tectonics.