Turonian
Second Late Cretaceous age, recalling Touraine and a nineteenth-century redivision of French marine faunas.
Language and route: Scientific French from Latin regional name Turonia → French Touraine. Latin Turonia (Touraine/Tours) → French Turonien → English Turonian.
Literal gloss: ‘of/from Touraine’ (geographical; not a Greek compound)
The name and its history
Alcide d’Orbigny · 1842 (reduced in extent after Cenomanian 1847 split)
- What does the word literally mean?
- ‘of/from Touraine’ (geographical; not a Greek compound)
- What did the original author mean?
- D’Orbigny initially used Turonian for a broad part of the chalk-and-tuffeau succession from western France, with the Le Mans fossil assemblage still included.
- Why was the name needed?
- Distinguishing fossil faunas of marine beds whose sediment types changed laterally required something more precise than chalk lithology alone.
- What evidence supported the original concept?
- Molluscan and rudist assemblages in Touraine and adjacent regions formed the initial basis, later prompting the separate Cenomanian.
- How has geology changed the concept?
- The present Turonian follows the Cenomanian; the internationally recognised base is not fixed by the limits of Touraine building stone.
Further historical context
D’Orbigny initially used Turonian for a broad part of the chalk-and-tuffeau succession from western France, with the Le Mans fossil assemblage still included.
Distinguishing fossil faunas of marine beds whose sediment types changed laterally required something more precise than chalk lithology alone.
Molluscan and rudist assemblages in Touraine and adjacent regions formed the initial basis, later prompting the separate Cenomanian.
The present Turonian follows the Cenomanian; the internationally recognised base is not fixed by the limits of Touraine building stone.
Editorial qualification
The label precedes Cenomanian; later usage should not be projected unaltered back onto the original 1842 concept.
Related names
Sources
- International Commission on Stratigraphy, International Chronostratigraphic Chart v2026/06 — Controlling nomenclature, rank and sequence of internationally recognised ages; not a historical-coinage source
- Peren Revues (2025), Turonian tuffeau of the original Touraine area — Differentiates d’Orbigny’s 1842 Turonian from Cenomanian split in 1847
- British Geological Survey, Geological Conservation Review: Upper Cretaceous rocks of the British Isles — Scholarly history of d’Orbigny, Coquand, Senonian and Maastrichtian stages
- d’Orbigny (1842), Paléontologie française, Terrains crétacés, Gastéropodes (catalogued scan) — Digitised bibliographic witness; individual first-use pages not independently checked