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Hirnantian

Geological interval

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The GSSP for the Hirnantian stage in the ICS geological timescale (uppermost Ordovician stage), located in the Wangjiawan profile (an outcrop of black shale, brownishly weathered siliceous shale and chert layers of the Wufeng Formation) along the G241 road, about 40 km north of Yichang, Hubei, China. An exact golden spike is missing in the profile (2025) but a memorial plague marks the place. The GSSP occurs at the first appearance of fossils of the graptolite species Normalograptus extraordinarius. It was ratified in 2006.

The GSSP for the Hirnantian stage in the ICS geological timescale (uppermost Ordovician stage), located in the Wangjiawan profile (an outcrop of black shale, brownishly weathered siliceous shale and chert layers of the Wufeng Formation) along the G241 road, about 40 km north of Yichang, Hubei, China. An exact golden spike is missing in the profile (2025) but a memorial plague marks the place. The GSSP occurs at the first appearance of fossils of the graptolite species Normalograptus extraordinarius. It was ratified in 2006.

China Hirnantian Ordovician fossil +1
Interpretation of the Hirnantian extinction and replacement of the Diplograptina (black) by the Neograptina (gray) (adapted from Bapst & others, 2012, fig. 1).
Intervals Hirnantian

Interpretation of the Hirnantian extinction and replacement of the Diplograptina (black) by the Neograptina (gray) (adapted from Bapst & others, 2012, fig. 1).

Hirnantian extinction