Middle Jurassic
The middle epoch of the Jurassic (and corresponding Middle Jurassic series), comprising Aalenian, Bajocian, Bathonian, Callovian.
Language and route: Modern English ordinal scientific term. English middle (time interval) and middle (corresponding series of rocks); not a coined Greek compound.
Literal gloss: middle / middle (position within the Jurassic)
The name and its history
Conventional stratigraphic division, not a single attributed coinage · Nineteenth–twentieth-century international stage standardisation
- What does the word literally mean?
- English ‘middle’ in sequence; stratigraphic Middle describes position in a rock succession.
- What did the original author mean?
- No individual coiner is asserted. These are conventional ordinal subdivisions within a Jurassic classification whose stage names and correlations were assembled over many decades.
- Why was the name needed?
- Geologists needed to express succession and correlation without treating one local lithology as a universal timescale. English Lias and oolite, German Black/Brown/White Jura and the international stage system are historically different classification routes.
- What evidence supported the original concept?
- Correlation of fossil zones and physical successions made it possible to distinguish middle Jurassic time from regional facies labels. The name does not imply a special biological event.
- How has geology changed the concept?
- The ICS defines the Middle Jurassic using global age/stage order. Dogger is borrowed from a Yorkshire rock term and in European practice came to denote the Middle Jurassic, but the British Dogger Formation and the Middle Jurassic epoch are different entities.
Further historical context
No individual coiner is asserted. These are conventional ordinal subdivisions within a Jurassic classification whose stage names and correlations were assembled over many decades.
Geologists needed to express succession and correlation without treating one local lithology as a universal timescale. English Lias and oolite, German Black/Brown/White Jura and the international stage system are historically different classification routes.
The ICS defines the Middle Jurassic using global age/stage order. Dogger is borrowed from a Yorkshire rock term and in European practice came to denote the Middle Jurassic, but the British Dogger Formation and the Middle Jurassic epoch are different entities.
Editorial qualification
No evidence that the common ordinal adjective was coined by one individual; distinguishing time from rocks is more important than assigning a false inventor.
Related names
Jurassic · Aalenian · Bajocian · Bathonian · Callovian · Lias · Dogger · Malm
Sources
- ICS International Chronostratigraphic Chart, 2026/06 — Official current ranks and names; ages are subject to revision
- K. N. Page, British Lower Jurassic stratigraphy: an introduction (GCR) — Authoritative history of d’Orbigny, Oppel, Renevier and fossil zonation
- P. Fauré, Le Jurassique: divisions et étages, histoire de la géologie — French historiographical account; some first-year claims conflict with other accounts