Answer:
Mantle convection
Explanation:
The source of the force that moves tectonic plates along plate boundaries is as a result of the mantle convection.
- Heat energy produced in the mantle especially from radioactive decay is a very important source of internal heat that drives plate motion.
- Denser and cold materials close to the over-riding lithosphere above sinks deep into the mantle.
- Hotter and lighter materials rises to the surface.
- This sets up a convection cell by which the plates above are driven.
