Homerium

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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 homerium in geological history is the upper chronostratigraphic level of the Wenlock series of the Silurian . The level extends geochronologically from about 430.5 to about 427.4 million years. The gorstium follows the homerium , the level is preceded by the sheinwoodium .

Naming and history

The stage is named after Homer (Shropshire) in Shropshire ( England ). The name was suggested by a group of English geologists (Bassett et al.) In 1975.

Definition and GSSP

The base of the stage is the first appearance of the graptolite species Cyrtograptus lundgreni . The upper limit lies near the base of the Neodiversograptus nilssoni graptolite zone and slightly below the base of the local Leptobrachion longhopense acritic zone . The official reference profile (GSSP = "Global Stratotype Section and Point") for the Homerium was defined as a stream profile in the Whitwell grove, 500 m north of Homer.

Breakdown

The homerium is subdivided into two conodont zones and four graptolite zones, although the upper limit probably does not exactly match the upper limit of the Colonograptus ludensis zone.

Conodonts:

Graptolites:

literature

  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2004, ISBN 978-0-521-78673-7 .
  • MG Basset, LRM Cooks, CH Holland, RB Rickards and PT Warren: The type Wenlock series. In: Report of the Institute of Geological Sciences. 75/13: 1-19, London 1975, ISSN  0073-9359
  • MG Bassett: The Wenlock Series in the Wenlock Area. In: CH Holland and MG Bassett (eds.): A global standard for the Silurian System. In: National Museum of Wales, Geological Series. 9: 51-73, Cardiff 1989 ZDB -ID & key = zdb 995874-5 .

Web links