Stratigraphy Model

The scientific study of the measurement of time

The oldest element in a set with the same parent element

An eonothem is a chronostratigraphic unit greater than an erathem. The geochronologic equivalent is an eon. Three eonothems are generally recognized, from older to younger, the Archean, Proterozoic and Phanerozoic eonothems. The combined first two are usually referred to as the Precambrian.

The eons take the same name as their corresponding eonothems.

An erathem is a chronostratigraphic unit greater than a system consisting of several systems.

The geochronologic equivalent of an erathem is an era.

The names of erathems in the Phanerozoic were chosen to reflect major changes of the history of life on Earth: Paleozoic (old life), Mesozoic (intermediate life), and Cenozoic (recent life). Eras carry the same name as their corresponding erathems.

The youngest element in a set with the same parent element

The bottom-most stratigraphic unit in a set with the same parent unit

The middle stratigraphic unit in a set with the same parent unit

The series is a chronostratigraphic unit ranking above subseries or stages and below a system. A series consists of several consecutive subseries, or (when subseries are not used) of several consecutive stages.

The geochronologic equivalent of a series is an epoch.

A stage is the lowest ranking unit in the chronostratigraphic hierarchy that can be recognized on a global scale.

A stage includes all rocks deposited between two chronostratigraphic horizons defined by GSSPs.

The scientific study of layers (strata) of rock, soil, sediment, or archaeological deposits and their arrangement through time

A subseries is a chronostratigraphic unit ranking immediately above stages and below a series. It consists of one or several consecutive stages.

The geochronologic equivalent of a subseries is a subepoch.

A system is a unit of major rank in the conventional chronostratigraphic hierarchy, above a series and below an erathem. A system is composed of several consecutive series.

The geochronologic equivalent of a system is a period. As an exception, the rank of subsystem (Mississippian, Pennsylvanian) is used for the Carboniferous System.

The highest stratigraphic unit in a set with the same parent unit

A specified position within an agreed stratigraphic section, used to calibrate the temporal position (age) of a boundary within the geologic timescale.

A position of a Chronometric element relative to another

• Early ^c
• Late ^c

A position of something relative to another

• Relative Chronometric Position ^c
• Relative Stratigraphic Position ^c

A major area or branch of scientific study

• Chronometric ^c
• Stratigraphic ^c

A position of a Stratigraphic Unit relative to another

• Lower ^c
• Middle ^c
• Upper ^c

An agreed Geologic Unit, which may a stratigraphic point that is used to calibrate the temporal position (age) of a boundary within the geologic timescale.

• Eonothem ^c
• Erathem ^c
• Series ^c
• Stage ^c
• Subseries ^c
• System ^c

GSSPs are reference points on stratigraphic sections of rock which define the lower boundaries of stages on the International Chronostratigraphic Chart