Branch of Geology

Specialized subfields within geology, each focused on one class of rock, geological process, structure or economically significant deposit rather than the whole discipline. Includes subfields organized by rock type and process (petrology, sedimentology, structural geology, stratigraphy), by dating method (geochronology), by mineral composition (mineralogy), by volcanic activity (volcanology), by cave and karst systems (speleology), and by economically valuable deposits (economic geology). Belongs here: any named subdiscipline of geology with its own defined subject matter narrower than geology as a whole. Does not belong here: geology itself, the parent discipline these subfields divide (Earth Science), or a subfield whose primary tools are geophysical measurement rather than direct study of rock (Geophysical Science).