Stratifografi

Stratifografi, commonly known as stratigraphy, is the branch of geology that studies the arrangement and characteristics of rock layers (strata). It seeks to describe, classify, map, and interpret the sequence, distribution, and relative ages of sediments and other layered rocks to understand the geological history of an area.

The analysis rests on fundamental principles such as the law of superposition, which states that younger rocks lie above older ones; original horizontality, suggesting beds were deposited largely parallel to the Earth's surface; lateral continuity, indicating beds extend laterally; and the recognition of unconformities, which record gaps in the stratigraphic record. By applying these, researchers can correlate beds across distances and reconstruct depositional environments.

Stratigraphy encompasses several subdisciplines: lithostratigraphy (correlation by rock type and formation boundaries); biostratigraphy (using fossil assemblages to align sections); chronostratigraphy (defining and dating time-based units in the geologic timescale); sequence stratigraphy (analysis of deposition in defined sequences related to sea-level changes); and magnetostratigraphy (record of Earth's magnetic reversals).

Dating in stratigraphy combines relative methods with absolute dating, where radiometric ages or tied-event dates from volcanic ash beds place strata on the geologic time scale. Stratigraphic information underpins resource exploration, groundwater studies, civil engineering, paleoenvironmental reconstructions, and archaeological context.

The development of stratigraphy progressed from early observations by Nicolaus Steno to later refinements by geologists such as James Hutton and Charles Lyell, leading to a formal geologic time scale and standardized stratigraphic methods used in field mapping and research today.