Short answers, pulled from the story.
Alfred Wegener proposed the theory of continental drift in the winter of 1912. He presented his ideas while standing in the Greenland ice and observing the fit between the eastern coast of South America and the western coast of Africa. His theory suggested that landmasses were once joined in a single supercontinent called Pangaea and had drifted apart over millions of years.
Harry Hammond Hess used evidence from the ocean floor discovered by a team led by Maurice Ewing aboard the research vessel Atlantis in 1947. He observed that the ocean floor was a rugged landscape dominated by mid-ocean ridges where new oceanic crust was being created. This observation led him to propose that the ocean floor acted like a conveyor belt carrying old crust away from the ridges until it sank back into the mantle at deep ocean trenches.
Fred Vine and Drummond Matthews proved that the ocean floor was spreading by analyzing magnetic stripes recorded in the basalt of the ocean floor during the 1950s. They found that the ocean floor displayed a zebra-like pattern of alternating bands of normal and reversed polarity that were symmetrical on either side of the mid-ocean ridges. This pattern provided irrefutable proof that new magma erupted at the ridges recorded the Earth's magnetic field at that time and that the seafloor was spreading.
The primary driving force behind plate motion is slab pull, which occurs when cold, dense oceanic lithosphere sinks into the mantle at subduction zones. As oceanic lithosphere ages and moves away from mid-ocean ridges, it cools, thickens, and becomes denser than the underlying asthenosphere. This process pulls the rest of the plate along with it, making plates attached to subducting slabs move much faster than plates that are not being subducted.
The most violent and active regions on the planet are located at the boundaries where plates meet, specifically at convergent boundaries where plates collide. The Pacific Ocean is ringed by these destructive boundaries known as the Ring of Fire, which hosts the majority of the world's active volcanoes and earthquakes. These interactions are also responsible for the formation of mountain ranges such as the Himalayas and the Andes.