Drumium

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system series step ≈ age ( mya )
higher higher higher younger
Cambrian Furongium 10th stage 485.4
⬍
489.5
Jiangshanium 489.5
⬍
494
Paibium 494
⬍
497
Miaolingium Guzhangium 497
⬍
500.5
Drumium 500.5
⬍
504.5
Wuliuum 504.5
⬍
509
2nd series 4th stage 509
⬍
514
3rd stage 514
⬍
521
Terreneuvium 2nd stage 521
⬍
529
Fortunium 529
⬍
541
deeper

The drumium is the middle chronostratigraphic stage of the Miaolingium , the third chronostratigraphic series of the Cambrian . The drumium follows the wuliuum and precedes the guzhangium . The drumium stage lasted from 504.5 million years ago to 500.5 million years ago.

Naming and history

The stage is named after the Drum Mountains ( Juab County , Utah , USA). The name was proposed by a group of authors around Loren E. Babcock in 2007.

Definition and GSSP

The lower limit is defined by the first appearance of the trilobite species Ptychagnostus atavus . The upper limit is the first appearance of the trilobite species Lejopyge laevigata . The GSSP (Borderline Stratotype Profile and Borderline Stratotype Point) was established in the Drum Mountains, Utah , USA .

literature

  • Loren E. Babcock, Richard A. Robison, Margaret N. Rees, Shanchi Peng and Matthew R. Saltzman: The Global boundary Stratotype Section and Point (GSSP) of the Drumian stage (Cambrian) in the Drum Mountains, Utah, USA. Episodes. 30 (2): 102-109, Beijing 2007 ISSN  0705-3797 .
  • Felix Gradstein, Jim Ogg and Alan Smith: A Geologic timescale. Cambridge University Press 2004 ISBN 978-0-521-78673-7 .

Web links