Asselian
The age of the Cisuralian interval (Permian), approximately 298.9–293.52 Ma according to the ICS June 2026 chart.
Language and route: Russian river-name. Russian river-name → international English. Named after Assel River, southern Urals.
Literal gloss: from the Assel River
The name and its history
V. E. Ruzhentsev (mid-twentieth-century formal subdivision; 1954 frequently cited) · See attributed dates and cited original / standardisation works; first-use priority qualified where noted
- What does the word literally mean?
- From the assel river. Immediate scientific language-route: Russian river-name → international English. This is a locality-based or geographical term, not a description of a universal geological event.
- What did the original author mean?
- A basal Uralian Permian fossil-faunal interval distinguished from what had earlier been grouped under the Artinskian.
- Why was the name needed?
- Finer study of the oldest Permian ammonoid and fusulinid succession showed that the former large Artinskian interval required a separately identified basal stage.
- What evidence supported the original concept?
- Fossil ammonoids and fusulinids were primary historical tools; the present basal Permian boundary is fixed at Aidaralash Creek in Kazakhstan using conodont correlation.
- How has geology changed the concept?
- The Asselian is now the first global Permian stage; the historic lower Permian boundary was once placed much higher, near deposits now assigned to the Kungurian.
Further historical context
*Naming and context.* Finer study of the oldest Permian ammonoid and fusulinid succession showed that the former large Artinskian interval required a separately identified basal stage.
*Evidence and later scope.* Fossil ammonoids and fusulinids were primary historical tools; the present basal Permian boundary is fixed at Aidaralash Creek in Kazakhstan using conodont correlation. The Asselian is now the first global Permian stage; the historic lower Permian boundary was once placed much higher, near deposits now assigned to the Kungurian.
Editorial qualification
Chronological priority of the term is not fully settled: some secondary tables mention 1937 while accounts of the modern independent stage favour 1954.
Related names
Permian · Cisuralian · Sakmarian · Artinskian · Kungurian · Gzhelian · Fossil · Conodont · Ammonoid
Sources
- ICS International Chronostratigraphic Chart (June 2026) — Current formal unit, order, rank and numerical age
- ICS Subcommission on Permian Stratigraphy, Asselian stage — History of downward Permian boundary revision and Russian fossil succession
- Jin et al. (1997), Permian chronostratigraphic subdivisions, Episodes — International decision to adopt Urals, Texas and South China tripartition