Geology is the study of the earth's landmasses. The earth is constantly changing. Often changes are to slow to be able to see them in a human lifetime. Forces cause different things to happen on the surface of the earth (Such as Mountains growing and eroding). Scientists believe that the earth was formed by very dense elements such as iron and nickel which are in the core of the earth. The earth's crust covers the mantle. The crust is made up of over two thousand different compounds called minerals. The crust is the outer most and thinnest layer. It ranges between four and seven kilometers. The mantel is sits right below the crust and is about two thousand nine hundred kilometers thick. As you go deeper into the mantel is becomes hotter and more pressurized.
             The upper part of the mantel and the crust make up the lithosphere. The lithosphere is the dense, solid layer that surrounds the earth; we call it the ground. There are giant plates that sit on top of the earth's mantle. These plates are very large rigid slabs of crustal rock that float on top of the mantel. The lighter plates carry the most landmass and the more dense plates carry less landmass. These plates are like large sheets of ice siting on top of a pond and like the ice they do not sit still. Scientist believe that the plates are driven by convection currents in the mantle. There are nine major plates. These plates have boundaries. There are different types of boundaries. A divergent boundary is when two plates move apart from one another. A convergent boundary is when two plates move towards each other. A transform boundary is when two plates slide horizontally past each other these boundaries are also called faults.
             Most earthquakes are caused by the sudden slip along geologic faults. The faults slip because of movement of the earth's tectonic plates. This concept is called the elastic rebound theory. The rocky tectonic plates move very slowly, floating on top of a w...