Aeronium

from Wikipedia, the free encyclopedia
system series step ≈ age ( mya )
higher higher higher younger
Silurian Pridolium 419.2

423
Ludlow Ludfordium 423

425.6
Gorstium 425.6

427.4
Wenlock Homerium 427.4

430.5
Sheinwoodium 430.5

433.4
Llandovery Telychium 433.4

438.5
Aeronium 438.5

440.8
Rhuddanium 440.8

443.4
deeper deeper deeper older

The aeronium is the second chronostratigraphic stage of the Llandovery series of the Silurian in the history of the earth . In absolute numbers ( geochronologically ), the stage is roughly in the period from about 440.8 to 438.5 million years. It follows the Rhuddanium and is overlaid by the Telychium .

Naming and history

The stage is named after the Cwm-coed Aeron Farm, near Llandovery , ( Wales ). The stage (and name) was proposed in 1971 by a British geological group under LRM Cocks.

Definition and GSSP

The beginning of the aeronium is defined by the first appearance of the graptolite species Monograptus austerus sequens . The upper limit is above the extinction horizon of the brachiopod species Eocoelia intermedia and below the first appearance of the brachiopod species Eocoelia curtisi . The boundary is also near the base of the Monograptus turriculatus graptolite zone. The official reference profile (GSSP = "Global Stratotype Section and Point") for the Aeronium is the "Transect h" on the Trefawr Forest Trail, north of the Cwm-coed-Aeron Farm, near Llandovery ( Wales ).

literature

  • Felix M. Gradstein, James G. Ogg, and Alan G. Smith (Eds.): A Geologic Time Scale 2004 . Cambridge University Press, Cambridge (UK) 2005. ISBN 0-521-78673-8
  • LRM Cocks: The Llandovery Series in the Llandovery area. In: CH Holland and MG Bassett (eds.). A global standard for the Silurian System. National Museum of Wales, Geological Series 9: 36–50, Cardiff 1989 ZDB -ID & key = zdb 995874-5 .

Web links