Chronostratigraphy

Chronostratigraphy classifies and correlates rock bodies according to their age and time of formation. It establishes a framework for ordering and comparing geological events across regions.

Stratigraphy: The study of layered rocks, their relationships, and the events recorded in them. Chronostratigraphy is the time-based branch of this broader study.
Global Boundary Stratotype Section and Point: An internationally designated physical reference point defining the lower boundary of a geological stage. A GSSP anchors many chronostratigraphic boundaries to a specific rock section.
International Commission on Stratigraphy: The international body that maintains global stratigraphic standards and the geologic time scale. It coordinates the formal definitions and boundaries used in global chronostratigraphy.
Lithostratigraphy: The classification of rock bodies according to observable lithologic characteristics. Lithostratigraphic boundaries follow rock properties, which may cross time boundaries.
Geologic time scale: A hierarchical system dividing Earth’s history into named units based on geological evidence. Its time intervals provide the framework that chronostratigraphic units represent.
Biostratigraphy: The use of fossil content and distribution to interpret and correlate sedimentary rock layers. Fossil succession helps correlate strata and locate boundaries in time.
Quaternary: The current geological period, beginning about 2.58 million years ago and continuing today. Its subdivisions show how chronostratigraphic units organize recent Earth history.
Biostratigraphic unit: A rock body defined by its fossil content and distribution. Its boundaries depend on fossil evidence rather than necessarily marking equal-age rock.
Chronostratigraphic unit: A body of rock formed during a specific interval of geological time. These are the rock units chronostratigraphy defines and correlates.
Magnetostratigraphy: The study of magnetic-polarity patterns preserved in rock sequences. Reversals in Earth’s magnetic field provide time markers for matching strata.

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