geology

Scientific study of the Earth, including its composition, structure, physical properties, and history. Geology is commonly divided into subdisciplines concerned with the chemical makeup of the Earth, including the study of minerals (mineralogy) and rocks (petrology); the structure of the Earth (structural geology) and volcanic phenomena (volcanology); landforms and the processes that produce them (geomorphology and glaciology); geologic history, including the study of fossils (paleontology), the development of sedimentary strata (stratigraphy), and the evolution of planetary bodies and their satellites (astrogeology); and economic geology and its various branches, such as mining geology and petroleum geology. Some major fields closely allied to geology are geodesy, geophysics, and geochemistry. See also environmental geology.