Chronozone

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A chronozone or chron is a slice of time that begins at a given event and ends at another. It is non-hierarchical[1] in that chronozones do not need to correspond across geographic or geologic boundaries, nor be equal in length. A chronozone is usually defined in geologic terms for a geographical area by fossil names (biozone or biochronozone) or in world-wide terms by geomagnetic reversal identifiers (polarity chronozone).

Chronozones can be members of each other, for example the chronozone known as the Reign of Tiberius (14 to 37 AD) is a subset of the chronozone Imperial Rome. Similarly the chronozone Pleistocene is a subset of the chronozone Neogene.

According to the International Commission on Stratigraphy, chronozone is the term used to refer to the rocks formed during the period of time in question, while the word chron refers to that time period.[2]

[edit] Notes

  1. ^ An early use in Harland, W.B., Armstrong, R.L., Cox, A.V., Craig, L.E., Smith, A.G., and Smith, D.G. (1989) A Geologic Time Scale Cambridge Univ. Press, Cambridge, was hierarchical in that chronozone was used for the slice of time smaller than a stage. This usage has been superseded by the ICS.
  2. ^ [http://www.stratigraphy.org/magn.htm "Magnetostratigraphic polarity units " International Commission on Stratigraphy]
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