Drumian

The Drumium is the average chronostratigraphic stage of the third, yet unnamed series of the Cambrian in the Earth's history. The Drumium is under - and overlain by a yet unnamed stage from Guzhangium. The Drumium stage lasted from about 504.5 million years to about 500.5 million years.

Naming and history

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

Definition and GSSP

The lower limit is defined by the first appearance of trilobites atavus Type Ptychagnostus. The upper limit is the first appearance of the trilobite type Lejopyge laevigata. The GSSP (boundary stratotype profile and boundary stratotype point) specified in the Drum Mountains, Utah, USA.