Early Jurassic
The early epoch of the Jurassic (and corresponding Lower Jurassic series), comprising Hettangian, Sinemurian, Pliensbachian, Toarcian.
Language and route: Modern English ordinal scientific term. English early (time interval) and lower (corresponding series of rocks); not a coined Greek compound.
Literal gloss: early / lower (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 ‘early’ in sequence; stratigraphic Lower 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 early 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 Lower Jurassic using global age/stage order. Lias began as a British quarrymen’s rock term and became associated with the Lower Jurassic, but lithostratigraphic Lias does not equal a globally synchronous series.
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 Lower Jurassic using global age/stage order. Lias began as a British quarrymen’s rock term and became associated with the Lower Jurassic, but lithostratigraphic Lias does not equal a globally synchronous series.
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 · Hettangian · Sinemurian · Pliensbachian · Toarcian · 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