Scientific study of the Earth, including its composition, structure, physical properties, and history. The term geology is broadly inclusive and is often regarded as embracing all of the geologic sciences. Geology is commonly divided into a number of subdisciplines: (1) mineralogy and petrology, (2) structural geology and volcanology, (3) geomorphology and glacial geology, (4) paleontology, stratigraphy and astrogeology, and (5) economic geology and its various branches.