Telychian
The age of the Llandovery interval (Silurian), approximately 438.6–432.9 Ma according to the ICS June 2026 chart.
Language and route: Welsh locality. Welsh locality → international English. Named after Pen-lan-Telych Farm, type Llandovery area, Wales.
Literal gloss: named for Pen-lan-Telych
The name and its history
Cocks, Toghill & Ziegler (1970); base revised and approved in 1984 · See attributed dates and cited original / standardisation works; first-use priority qualified where noted
- What does the word literally mean?
- Named for pen-lan-telych. Immediate scientific language-route: Welsh locality → international English. This is a locality-based or geographical term, not a description of a universal geological event.
- What did the original author mean?
- Originally the uppermost part of a four-stage Llandovery scheme, subsequently retained with an altered basal definition.
- Why was the name needed?
- The original Telychian provided an upper part of a proposed fourfold Llandovery succession. Later international deliberation retained the term but changed its lower boundary.
- What evidence supported the original concept?
- Graptolite zonation and renewed study of Welsh roadcuts were used to improve correlation over the earlier facies-dependent local divisions.
- How has geology changed the concept?
- The present Telychian is the youngest of three Llandovery stages. Its formal base is not exactly the 1970 proposal.
Further historical context
*Naming and context.* The original Telychian provided an upper part of a proposed fourfold Llandovery succession. Later international deliberation retained the term but changed its lower boundary.
*Evidence and later scope.* Graptolite zonation and renewed study of Welsh roadcuts were used to improve correlation over the earlier facies-dependent local divisions. The present Telychian is the youngest of three Llandovery stages. Its formal base is not exactly the 1970 proposal.
Editorial qualification
Retained name does not imply unchanged stratigraphic extent.
Related names
Silurian · Llandovery · Rhuddanian · Aeronian · Graptolite · Stratigraphy · Facies
Sources
- ICS International Chronostratigraphic Chart (June 2026) — Current formal unit, order, rank and numerical age
- Cocks, Toghill & Ziegler (1970), Stage Names within the Llandovery Series — Original four-stage proposal, later modified
- Holland (1984), Steps to a Standard Silurian — Contemporaneous committee history and Aeronian name
- ICS international GSSPs: Silurian stages and boundary issues — Modern formal references, rank, locations and correlation
- Geological Survey educational compilation of Silurian stage name origins — Locality/name origin, not original creation priority