The following is a brief overview of the meaning, makeup and origin of the subject of Geology.

  1. Geology comes from Greek ge (“the earth") and logos ("word", "reason").
  2. It is the science and study of the solid matter of a celestial body, its composition, structure, physical properties, history and the processes that shape it. It is one of the Earth sciences.
  3. Geologists have helped establish the age of the Earth at about 4.6 billion (4.6x109) years, and have determined that the Earth's lithosphere, which includes the crust, is fragmented into tectonic plates that move over a rheic upper mantle (asthenosphere) via processes that are collectively referred to as plate tectonics.
  4. Geologists help locate and manage the earth's natural resources, such as petroleum and coal, as well as metals such as iron, copper, and uranium.
  5. Additional economic interests include gemstones and many minerals such as asbestos, perlite, mica, phosphates, zeolites, clay, pumice, quartz, and silica, as well as elements such as sulphur, chlorine, and helium.
  6. Astrogeology refers to the application of geologic principles to other bodies of the solar system. However, specialised terms such as selenology (studies of the Moon), areology (of Mars), etc., are also in use.
  7. The word "geology" was first used by Jean-André Deluc in the year 1778 and introduced as a fixed term by Horace-Bénédict de Saussure in the year 1779. An older meaning of the word was first used by Richard de Bury. He used it to distinguish between earthly and theological jurisprudence.