n.
Scientific discipline concerned with describing rock successions and interpreting them in terms of a general time scale.
It provides a basis for historical geology, and its principles and methods are applied in such fields as petroleum geology and archaeology. Stratigraphic studies deal primarily with sedimentary rocks but may also encompass layered igneous rocks (e.g., those resulting from successive lava flows) or metamorphic rocks formed either from such extrusive igneous material or from sedimentary rocks.