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video on stratigraphy

November 17, 2010 2 comments

This guy might have a silly voice and video, but the video does explain well;)

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Chrono Stratigraphic

November 17, 2010 Comments off

Wikipedia definition!

Chronostratigraphy is the branch of stratigraphy that studies the age of rock strata in relation to time.

The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of the Earth.

The standard stratigraphic nomenclature is a chronostratigraphic system based on palaeontological intervals of time defined by recognised fossil assemblages (biostratigraphy). The aim of chronostratigraphy is to give a meaningful age date to these fossil assemblage intervals and interfaces.

Another explanation:)

The term chronostratigraphy refers to that aspect of the field of stratigraphy dealing with temporal (time) relations and ages of rock bodies. Chronostratigraphic classification in the field of stratigraphy organizes rocks on the basis of their age or the time of their genesis.

  • Chronostratigraphic units are defined as bodies of rock—stratified and non-stratified—that formed during a specific interval of geologic time.
  • Chronostratigraphic units are thus special rock bodies that are conceptual, as well as being material. They can be thought of as the subset of rocks formed during a specified geologic time interval.

For example, the Devonian System is the set of all rocks (sedimentary as well as igneous and metamorphic), wherever they occur on Earth, formed during the Devonian Period.

The boundaries of this conceptual set of rocks are synchronous (i.e., are the same age everywhere) and the Devonian System is isochronous (i.e., the same age and age span everywhere). When written with a proper noun, e.g., Devonian System, both parts of the name of any chronostratigraphic unit are capitalized.


  • Erathem—Corresponding geochronologic term: Eon; Example: Phanerozoic
  • Eonothem—Corresponding geochronologic term: Era; Example: Paleozoic
  • System—Corresponding geochronologic term: Period; Example: Devonian
  • Series—Corresponding geochronologic term: Epoch; Example: Late Devonian
  • Stage—Corresponding geochronologic term: Age; Example: Frasnian
  • Substage—Corresponding geochronologic term: Subage




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