Kimmeridgian
Late Jurassic age named for Kimmeridge Clay of Dorset; its global base was ratified at Skye in 2021.
Language and route: International scientific terminology from English village and rock-unit name. English village and rock-unit name place-name Kimmeridge → international scientific stage-name Kimmeridgian (English); older place-name origin not inferred.
Literal gloss: of/from Kimmeridge
The name and its history
Thurmann (early usage) and d’Orbigny (stage codification): priority disputed · 1830s–1850s (disputed)
- What does the word literally mean?
- ‘of/from Kimmeridge’, referring to Kimmeridge in Dorset, England and the Kimmeridge Clay.
- What did the original author mean?
- Black fossil-rich mudstones exposed at Kimmeridge already had a local formation name; their association with late Jurassic faunas provided a recognisable reference for a stage. Historical sources differ over the first formal scientific stage application.
- Why was the name needed?
- Strata across Britain and continental Europe varied between marine clays, limestones and other facies, so formation bounds did not form a transferable time division.
- What evidence supported the original concept?
- The evidence came from extensive fossil successions, especially ammonites; later workers disagreed over the intervening “Corallian” beds and uppermost stage limits.
- How has geology changed the concept?
- The Kimmeridgian’s basal GSSP was ratified in 2021 at Flodigarry, Isle of Skye, Scotland—not at Kimmeridge. Its modern upper boundary is adjacent to the Tithonian.
Further historical context
The name invokes Kimmeridge in Dorset, England and the Kimmeridge Clay. Black fossil-rich mudstones exposed at Kimmeridge already had a local formation name; their association with late Jurassic faunas provided a recognisable reference for a stage. Historical sources differ over the first formal scientific stage application.
Strata across Britain and continental Europe varied between marine clays, limestones and other facies, so formation bounds did not form a transferable time division. The evidence came from extensive fossil successions, especially ammonites; later workers disagreed over the intervening “Corallian” beds and uppermost stage limits.
The Kimmeridgian’s basal GSSP was ratified in 2021 at Flodigarry, Isle of Skye, Scotland—not at Kimmeridge. Its modern upper boundary is adjacent to the Tithonian.
Editorial qualification
Some general historical tables credit Thurmann (1832); specialised surveys identify d’Orbigny’s stage (mid-nineteenth century). These claims need original-publication comparison.
Related names
Jurassic · Oxfordian · Tithonian · Ammonite · Lithofacies
Sources
- ICS International Chronostratigraphic Chart, 2026/06 — Official current ranks and names; ages are subject to revision
- Oxfordian and Kimmeridgian stratigraphy, Geological Conservation Review — Reassessment of regional stages and Oxfordian/Callovian limits
- ICS Subcommission on Jurassic Stratigraphy, stage working groups — Individual stage boundary status and GSSP locations
- P. Fauré, Le Jurassique: divisions et étages, histoire de la géologie — French historiographical account; some first-year claims conflict with other accounts