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The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon.
Geologic time, the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins with the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day. Modern geologic time scales also include the Hadean Eon (4.6 billion to 4.0 billion years ago).
A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and is calibrated in years (Harland and others, 1982). Over the years, the development of new dating methods and the refinement of previous methods have stimulated revisions to geologic time scales.
Geologic time scale showing the geologic eons, eras, periods, epochs, and associated dates in millions of years ago (MYA).
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy).
The geologic time scale is a system used by scientists to describe Earth's history in terms of major geological or paleontological events (such as the formation of a new rock layer or the appearance or demise of certain lifeforms).
Interactive Geological Timescale. This visualisation of the International Commission on Stratigraphy 's Chronostratigraphic Chart uses the SKOS & Time Ontology in OWL representation of it as the Geological Timescale (2020) for its data.
From the smallest unit of time, the epoch, to the largest unit, the eon, each division is defined by specific events and changes that took place on Earth. Understanding the divisions of time in the Geologic Time Scale is an important step in comprehending the complex history of our planet.
Our geologic time scale was constructed to visually show the duration of each time unit. This was done by making a linear time line on the left side of the time columns. Thicker units such as the Proterozoic were longer in duration than thinner units such as the Cenozoic.
The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon. Names of units and age boundaries usually follow the Gradstein et al. (2012), Cohen et al. (2012), and Cohen et al. (2013, updated) compilations.