Systems in The Geological Timescale
The systems of the Phanerozoic Eonothem were defined during the 19th century, beginning with the Cretaceous (by Belgian geologist Jean d'Omalius d'Halloy in the Paris Basin) and the Carboniferous (by British geologists William Conybeare and William Phillips) in 1822. The Paleozoic and Mesozoic erathems were divided into the currently used systems before the second half of the 19th century, except for a minor revision when the Ordovician system was added in 1879.
The Cenozoic Era has seen more recent revisions by the International Commission on Stratigraphy. It has been divided into three systems with the Paleogene and Neogene replacing the former Tertiary System though the succeeding Quaternary remains. The one-time system names of Paleocene, Eocene, Oligocene, Miocene and Pliocene are now series within the Paleogene and Neogene.
Another recent development is the official division of the Proterozoic Eonothem into systems, which was decided in 2004.
Read more about this topic: System (stratigraphy)
Famous quotes containing the words systems and/or geological:
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