Neocomian
A historical, variably delimited lower-Cretaceous division; not a current international epoch or stage.
Language and route: Scientific French Néocomien from Latinised Swiss locality. Latin Neocomum (Neuchâtel, ‘new castle’) → French Néocomien → English Neocomian.
Literal gloss: ‘of Neocomum’, a Latinised name of Neuchâtel
The name and its history
Jules Thurmann · 1835 (1836 also quoted in historical literature)
- What does the word literally mean?
- ‘of Neocomum’, a Latinised name of Neuchâtel
- What did the original author mean?
- Thurmann gathered fossil-bearing lower Cretaceous strata around Neuchâtel under the name Neocomian, before local workers recognised Valanginian and Hauterivian separately.
- Why was the name needed?
- Its geographical rock association became too broad and inconsistent to map a globally coherent time interval, and later authors included different additional intervals.
- What evidence supported the original concept?
- De Montmollin’s Neuchâtel descriptions, chalk/greensand correlations and subsequent local fossil work underlay the changing scheme.
- How has geology changed the concept?
- It persists in older books and informal regional discussions, but is excluded from the modern ICS stage nomenclature; it is not an exact time-equivalent of any single modern stage.
Further historical context
Thurmann gathered fossil-bearing lower Cretaceous strata around Neuchâtel under the name Neocomian, before local workers recognised Valanginian and Hauterivian separately.
Its geographical rock association became too broad and inconsistent to map a globally coherent time interval, and later authors included different additional intervals.
De Montmollin’s Neuchâtel descriptions, chalk/greensand correlations and subsequent local fossil work underlay the changing scheme.
It persists in older books and informal regional discussions, but is excluded from the modern ICS stage nomenclature; it is not an exact time-equivalent of any single modern stage.
Editorial qualification
Publication-year variation between 1835 and 1836 must not be treated as settled without inspecting dated editions.
Related names
Cretaceous · Berriasian · Valanginian · Hauterivian · Barremian
Sources
- International Commission on Stratigraphy, International Chronostratigraphic Chart v2026/06 — Controlling nomenclature, rank and sequence of internationally recognised ages; not a historical-coinage source
- Reboulet et al. (2013), stratigraphy of historic Neocomian around Neuchâtel, Carnets de Géologie — Historical reassessment of Thurmann, Desor, Renevier and the original Swiss successions
- Wimbledon et al. (2020), proposal for the Berriasian base, historical discussion — Discusses competing Neocomian interpretations, publication dates and boundary disagreement
- British Geological Survey, Geological Conservation Review: Upper Cretaceous rocks of the British Isles — Scholarly history of d’Orbigny, Coquand, Senonian and Maastrichtian stages