The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic epoch, or the lowest stage of the Upper Jurassic series. It spans the time between 163.5 ± 4 Ma and 157.3 ± 4 Ma (million years ago). The Oxfordian is preceded by the Callovian and is followed by the Kimmeridgian.
|163.5 ± 1.0 – 157.3 ± 1.0 Ma|
|Regional usage||Global (ICS)|
|Time scale(s) used||ICS Time Scale|
|Time span formality||Formal|
|Lower boundary definition||FAD of ammonite species Brightia thuouxensis|
|Lower boundary definition candidates||Horizon of the Ammonite Cardioceras redcliffense.|
|Lower boundary GSSP candidate section(s)|
|Upper boundary definition||FAD of the Ammonite Pictonia baylei|
|Upper boundary GSSP||Flodigarry, Skye, Scotland, UK|
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, 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.
The base of the Oxfordian stage is defined as the point in the stratigraphic record where the ammonite species Brightia thuouxensis first appears. A global reference profile for the base (a 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.
- "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy.
- "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 25 July 2021.
- For a detailed geologic timescale see Gradstein et al. (2004)
- Oxfordian is a word meaning "from Oxford" (see wiktionary:Oxfordian).
- public domain: Howe, John Allen (1911). "Oxfordian". In Chisholm, Hugh (ed.). Encyclopædia Britannica. 20 (11th ed.). Cambridge University Press. p. 415. One or more of the preceding sentences incorporates text from a publication now in the