The Sandbian is the first stage of the

Upper Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. Th ...

. It follows the

Darriwilian The Darriwilian is the upper stage of the Middle Ordovician. It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species ' ...

and is succeeded by the

Katian The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian millio ...

. Its lower boundary is defined as the

first appearance datum First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particu ...

of the

graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) through t ...

species '' Nemagraptus gracilis'' around million years ago. The Sandbian lasted for about 5.4 million years until the beginning of the

around million years ago.

Naming

The name Sandbian is derived from the village Södra Sandby ( Lund Municipality, Skåne County, Sweden). The name was proposed in 2006.

GSSP

The

GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted ...

of the Sandbian is the Fågelsång section () at Sularp Brook, east of Lund ( Skåne, Sweden). It is an outcrop of shale and mudstone. The lower boundary of the Sandbian is defined as the

species'' Nemagraptus gracilis'' in that section.

References

. Ordovician geochronology {{geology-stub