the branch of science concerned with the origin, small-scale structure, and composition of rocks. Compare with lithology, petrography.
/ ˌpetrəˈläjik/ adj.
/ ˌpetrəˈläjikəl/ adj.
/ -jist/ n.
The study of rocks in general, including their occurrence, field relations, structure, origins and history (petrogenesis
), and their mineralogy
). It may usefully be qualified as ‘igneous petrology’, or ‘sedimentary petrology’.
Study of rocks, including their origin, chemical composition, and location. Formation of the three classes of rocks – igneous
(of volcanic origin); sedimentary
(deposited by water); and metamorphic
(either of the other two changed by temperature and pressure) – is studied.