Plate TectonicsSince the beginning of time, humans believed that the ground was solid and immobile. But that's absolutely not true. The Earth is constantly evolving and continually moving. The stability of the Earth is not at all what we think. Thinking about the Earth's axis of rotation, and possibly what the Earth might become at any given time, has a great influence on understanding all aspects of living things, whether in the past, present or the future. The theory of plate tectonics is accredited for most of the creation of mountain ranges, the theory of centennial drift, for earthquakes and volcanic activity. Plate tectonics and mountains also play an important role in the Earth and its geological features. Geophysics, the study of the physics of the Earth, has led to many important discoveries about the Earth and how it is made up. Seismological studies of planet Earth have revealed new information about the Earth's interior, which has helped open up new insights into the theory of plate tectonics. Thanks to geophysical studies, we now know that the Earth is made up of several important layers. Each of these layers has its own properties. The crust is the outermost layer of the Earth. The crust is made up of the oceans and continents. The crust has a fluctuating thickness, ranging from thirty to seventy-five kilometers thick on continents and ten to fifteen kilometers thick in ocean basins. The crust consists mainly of alumino-silicates (Fowler p472). The layer beneath the crust is the mantle, made up mainly of ferromagnesium silicates. The mantle is approximately two thousand nine hundred kilometers thick and is separated into upper and lower mantle. It is in the mantle that most mid-paper centralized plates believe the North American and South American plates are moving westward about two to three centimeters per year. Based on earthquake records, the Haitian earthquake appears to have occurred near the Enriquillo Fault. The Enriquillo Fault is a large strike-slip fault that crosses the southern border of Haiti. Scientists speculate that this is the fault that likely ruptured because it is closest to the epicenter of the rupture. Although this was a great disaster for human life on the island of Haiti, it was not really unusual given the plate tectonic activity in this region. Unfortunately for Haiti, it is one of the poorest and underdeveloped countries in the world. His government was not really able to prepare for an earthquake of this magnitude, which caused the deaths of thousands of people (Kearey 2009).