Oxfordian (stage)

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Oxfordian
161.5 ± 1.0 – 154.8 ± 0.8 Ma
.
Lower boundary GSSP candidate section(s)
Upper boundary definition
Skye, Scotland, UK
57°39′40″N 6°14′44″W / 57.6610°N 6.2455°W / 57.6610; -6.2455
Upper GSSP ratified2021[2]

The Oxfordian is, in the

Ma and 154.8 ± 0.8 Ma (million years ago).[3] The Oxfordian is preceded by the Callovian and is followed by the Kimmeridgian
.

Stratigraphic definitions

The Oxfordian Stage was called "Clunch Clay and Shale" by William Smith (1815–1816); in 1818 W. Buckland described them under the unwieldy title "Oxford, Forest or Fen Clay". The term Oxfordian was introduced by Alcide d'Orbigny in 1844. The name is derived from the English city of Oxford,[4] where the beds are well developed, but they crop out almost continuously from Dorset to the coast of Yorkshire, generally forming low, broad valleys. They are well exposed at Weymouth, Oxford, Bedford, Peterborough, and in the cliffs at Scarborough, Red Cliff and Gristhorpe Bay. Rocks of this age are found also in Uig and Skye.[5]

The base of the Oxfordian Stage is defined as the point in the stratigraphic record where the

GSSP) had in 2009 not yet been assigned. The top of the Oxfordian Stage (the base of the Kimmeridgian) is at the first appearance of ammonite species Pictonia baylei
.

In the Tethys domain, the Oxfordian contains six ammonite biozones:

References

Notes

  1. ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy.
  2. ^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 25 July 2021.
  3. ^ "Stratigraphic Chart 2022" (PDF). International Commission on Stratigraphy. February 2022. Retrieved 22 April 2022.
  4. ^ Oxfordian is a word meaning "from Oxford" (see wiktionary:Oxfordian).
  5. ^  One or more of the preceding sentences incorporates text from a publication now in the public domainHowe, John Allen (1911). "Oxfordian". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 20 (11th ed.). Cambridge University Press. p. 415.

Literature

  • Brongniart, A.; 1829: Tableau théorique de la succession et de la disposition la plus générale on Europa, des terrains et roches, qui composent l'écorce de la terre, Paris.(in French)
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.

External links