According to the theory of Plate Tectonics, the surface of the Earth is comprised of several plates, some very large, and several smaller. The plates slowly move through time, changing size and shape. When the plates move against each other, they create geologic events such as earthquakes, volcanoes, mountains. The type of event depends on how the plates move relative to each other.
This movement of the Earth's surface impacts where oil and natural gas deposits can be found, which is why the study of Plate Tectonics is important to Petroleum Geologists.