Quaternary

The Quaternaire indicates one recent geological period (which currently continues) characterized by the return of glacial cycles . In Paléontologie the Quaternary one is marked by the development of the man.

Extended and definition

The definition of Quaternary is clearly climatic. But its lower limit remains difficult to pose because several markers of cold can be used (giving a lower limit between approximately 2,4 and 1,5 million years) before the glaciations are not manifest on the continents of the northern hemisphere.

A possible Stratotype is the cut of Vrica (Italy) corresponding to the appearance of the cold first Radiolaires bathiaux in the Mediterranean and whose age is estimated at 1,5 My (million years). However, other geomorphological elements, primarily and Géodynamique S (first Glaciation S in the northern hemisphere) proposes an age up to 2,4 My.

The Quaternary one is composed of the times of the Pléistocène and the Holocène (the latter, since approximately 10  000 years corresponding to the Interglaciaire that we currently live).

The statute of Quaternary in geological stratigraphy

The period of Quaternary was initially a geological era, natural extension of a division in eras including/understanding: Primary, Secondary, Tertiary (and preceded by the Precambrian ).

With the projection of the methods of dating of the oldest rocks, and after the discovery of fossils in the Precambrian rocks, this division in eras was forsaken, but the Quaternary one had been preserved in classification, as a last geological system after the Néogène.

However, the Néogène system was wide recently until our time; also, the Quaternary one is proposed in “subsystem” and does not appear any more in the stratigraphic scales simplifées most recent, according to the choice of the International commission of stratigraphy ( International Commission one Stratigraphy ). To note that this choice does not achieve the unanimity within the community of the geologists, especially in the specialists in the Quaternary one.

See too

External bonds

  • the site of the AFEQ French Association for the study of the Quaternary
  • the site of the CNF-INQUA French National committee of the '' International Union for Quaternary '' (International union on the Quaternary )

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