Roadian

The Roadium is the lower stratigraphic level (or age in geochronology ) of Mittelperm or Guadalupium series. In absolute terms, the level ranges from about 272.3 million years to about 268.8 million years. The Roadium following the Kungurian and is superimposed on Wordium.

Naming and history

Walter William Nassichuk presented in 1964 found that between the Wordium and the Russian Artinskian a further step can be eliminated. William Madison Furnish and Brian F. Glenister then led 1968 Roadium as basal stratigraphic sub- stage of their, at that time regional stage of Guadalupiums one. It is named after the basal unit of the Word Formation, the Road Canyon Member. 2001 Roadium was ratified as a global chronostratigraphic stage of the IUGS ​​.

Definition and GSSP

The base of Roadiums is defined by the first appearance of the conodont species Jinogondolella nanginkensis. The stage ends with the first appearance of the conodont species Jinogondolella aserrata. The reference profile ( GSSP ) of the Roadiums is in the Stratotype Canyon in the southern Guadalupe Mountains in Texas, USA (31 ° 52 ' 36.1 "N, 104 ° 52' 36.5 " W).