Alfred Wegner, a German meteorologist, pondered these questions. Wegner theorized that if South America and Africa were once combined as one continent, there would be similar geological formations such as mountain ranges, fossils, and glacial flow patterns. Upon carrying out several expeditions, he found that his theory was true. The evidence supporting Wegner's theory include: jigsaw fit, distribution of fossilized plants and animals across continent lines, the distribution of paleoclimate zones, the fit of geological structures and lithologies across boundaries, and recent measurement of true relative motion. Geologists agreed that Wegner's theory was proven by his evidence, yet they all showed resistance toward the idea. They claimed that "it is difficult to imagine a continent moving." They also claimed that there was a lack of a mechanism.
A glimpse of this mechanism was presented during a military study of the magnetic characteristics of the ocean floor. They were trying to learn about the "arena" for submarine warfare. The study showed that a ridge wherein a valley exists occupies the center of each major ocean. On each side of this valley, parallel stripes of rock are magnetized in opposite directions. The patterns are mirror images of each other.
Another theory presented, that explained continental drift, is that the continents "float" on a series of rigid plates within the earth. The driving force that keeps these ten plates moving in different directions is the heating and cooling of the mantle. As the inner portion of the mantle heats, air bubbles are formed, they float to the top, and cause movement on the surface. This is constantly happening and thus there are constant currents keeping the "push-pull" force of these plates constant. At the boundaries of these plates, there are a few things that can happen: the manufacturing of new oceanic plates, the plates slide along each other, the continental plates collide, and an oceanic plate is subducted under a continental plate.
The continents have been in motion for 4.6 billion years, and the modern world is still in motion today. North America is found to be drifting closer to Asia. In fact, satellite measurements show that North America is moving away from Europe at a rate of about 4cm per year. The movement along the fault lines creates the volcanoes and earthquakes in the Pacific Rim countries.
