The word Geology is derived from the Greek (geo=earth, logos=study) and deals with the study of the planet Earth, the materials of which it is made, the processes that affect Earth materials, the products formed in the Earth, and the history of the planet and of its inhabitants since its origin. Geologists study the composition of Earth materials and the various geological processes in order to locate and exploit Earth's mineral resources. Geologists also investigate earthquakes, volcanoes and other geological phenomena to predict and minimize the damaging effects from them. They also study geologic history in order to determine former positioning of the continents and oceans, the nature of ancient climates, and the evolution of life as revealed in fossil records.

The major branches of historical geology, like those of physical geology, overlap in a number of areas and are interdependent. The unification of physical and historical geology leads ultimately to a better understanding of the Earth.

Although geology is a relatively young science, humans have long been interested in the Earth. Prehistoric people utilized stones as tools and weapons, formed clay into pottery, and sought shelter in rocky caves. But their knowledge of the earth was restricted to the ground beneath their feet or the limited areas that they could explore on foot.

Now, with the use of technology, humans are delving further into the Earth's structure. With this advancement also comes the opportunity to be able to find and exploit more of the Earth's resources.