440.8 ± 1.2 – 438.5 ± 1.1 Ma
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionFAD of the graptolite Monograptus austerus sequens
Lower boundary GSSPTrefawr Track Section, Llandovery, Wales, UK
52°01′48″N 3°42′00″W / 52.0300°N 3.7000°W / 52.0300; -3.7000
GSSP ratified1984[4]
Upper boundary definitionJust above LAD of the brachiopod Eocoelia intermedia, below FAD of lowest succeeding species Eocoelia curtisi
Upper boundary GSSPCefn-cerig Road Section, Llandovery, Wales, UK
51°58′12″N 3°47′24″W / 51.9700°N 3.7900°W / 51.9700; -3.7900
GSSP ratified1984[4]

In the geologic timescale, the Aeronian is an age of the Llandovery epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that began 440.8 ± 1.2 Ma and ended 438.5 ± 1.1 Ma (million years ago). The Aeronian age succeeds the Rhuddanian age and precedes the Telychian age, all in the same epoch.[5]


The GSSP is located in the Trefawr Track section, 500m north of Cwm-coed-Aeron Farm, Wales, UK.[6] The GSSP lies within the gently-dipping blocky mudstones of the Trefawr Formation, which principally yield abundant and diverse shelly faunas, but also contain enough graptolites to allow recognition of several biozones.[7]


  1. ^ Jeppsson, L.; Calner, M. (2007). "The Silurian Mulde Event and a scenario for secundo—secundo events". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 93 (02): 135–154. doi:10.1017/S0263593300000377.
  2. ^ Munnecke, A.; Samtleben, C.; Bickert, T. (2003). "The Ireviken Event in the lower Silurian of Gotland, Sweden-relation to similar Palaeozoic and Proterozoic events". Palaeogeography, Palaeoclimatology, Palaeoecology. 195 (1): 99–124. doi:10.1016/S0031-0182(03)00304-3.
  3. ^ "Chart/Time Scale". International Commission on Stratigraphy.
  4. ^ a b Holland, C. (June 1985). "Series and Stages of the Silurian System". 8 (2): 101–103. doi:10.18814/epiiugs/1985/v8i2/005. Retrieved 15 December 2020. Cite journal requires |journal= (help)
  5. ^ "GSSP Table - All Periods". International Commission on Stratigraphy. Retrieved 2018-09-15.
  6. ^ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
  7. ^ "GSSP for Aeronian Stage". International Commission on Stratigraphy. Retrieved September 15, 2018.