Final answer:
Plate motion is driven by mantle convection, gravitational forces, radioactive decay, and variations in mantle temperature, all of which contribute to the complex movement of tectonic plates that shapes the Earth's surface over geological time scales.
Step-by-step explanation:
What Causes Plate Motion:
Plate motion is primarily caused by the phenomenon of mantle convection, which is a process similar to the boiling of water. In essence, heat from the Earth's interior causes the mantle to circulate. Hotter less dense material rises while cooler, denser material sinks setting up a cycle that exerts a force on the overlying tectonic plates. Additionally, gravitational forces contribute to plate motion, where denser oceanic plates dive beneath lighter continental plates in a process known as subduction. Radioactive decay within the Earth's core also releases heat which drives mantle convection. Finally variations in the mantle temperature help to facilitate different rates and directions of the flow of rock within the mantle influencing the motion of tectonic plates. Plate tectonics involves the movement of Earth's crustal plates that cover a molten iron core.
This movement can manifest in various ways with plates pulling apart colliding, and sliding past each other, leading to seismic activity and the creation of geologic features. The slow movement rate of these plates is generally at a pace similar to the growth of human fingernails, but the impact on the Earth's crust is substantial over geological time scales. In summary, the motion of tectonic plates is a complex interplay between various physical processes, all of which are a means for Earth to dissipate heat accumulated in its interior to the space outside, acting as a planetary cooling system.