Darriwilian
The Darriwilian Age/Stage within the Middle Ordovician (ICS 2026/06); about 469.4–458.2 Ma.
Language and route: Australian geographical place-name → international English. Australian geographical place-name → international English. Name-source: Darriwil (historical Darriwill), Victoria, Australia.
Literal gloss: named after Darriwil (historical Darriwill), Victoria, Australia
The name and its history
Thomas Sergeant Hall (1899), Australian regional name; global base ratified 1997 · Thomas Sergeant Hall (1899), Australian regional name; global base ratified 1997
- What does the word literally mean?
- Named from Darriwil (historical Darriwill), Victoria, Australia.
- What did the original author mean?
- Hall’s Darriwill Series denoted a regional Australian interval recognised in graptolite-bearing strata; the modern standard inherited the term.
- Why was the name needed?
- Australian graptolite assemblages required regional stratigraphic ordering; a century later international workers needed the same interval correlatable far beyond the Victorian type area.
- What evidence supported the original concept?
- Successive graptolite zones supported correlations; global base at the Huangnitang section in China follows first appearance of Undulograptus austrodentatus.
- How has geology changed the concept?
- Name retained internationally although the Victorian exposures were not suitable to define its globally fixed lower boundary; older Australian sense and modern duration differ.
Further historical context
*Original use. Hall’s Darriwill Series* denoted a regional Australian interval recognised in graptolite-bearing strata; the modern standard inherited the term.
*Historical problem.* Australian graptolite assemblages required regional stratigraphic ordering; a century later international workers needed the same interval correlatable far beyond the Victorian type area.
*Evolution.* Name retained internationally although the Victorian exposures were not suitable to define its globally fixed lower boundary; older Australian sense and modern duration differ.
Editorial qualification
Historical Darriwill/Darriwil spelling varies; Hall’s original description is cited through scholarly reviews, not claimed as inspected here word-for-word.
Related names
Ordovician · Middle Ordovician · Dapingian · Graptolite · Stratigraphy
Sources
- ICS International Chronostratigraphic Chart, 2026/06 — Current nomenclature, rank and numerical age
- ICS official Darriwilian GSSP — International boundary stratotype and correlation evidence
- Research paper recounting Hall’s 1899 Australian usage and the China GSSP — Historical naming, original claim or scholarly review; see confidence note
- ICS Ordovician Subcommission, full sequence — Cross-check order and stage nomenclature