Sandbian

The Sandbian is the first stage of the Upper Ordovician. It follows the Darriwilian and is succeeded by the Katian. Its lower boundary is defined as the first appearance datum of the graptolite species Nemagraptus gracilis around 458.2 million years ago. The Sandbian lasted for about 5.4 million years until the beginning of the Katian around 452.8 million years ago.^[7]

Sandbian
458.2 ± 0.7 – 452.8 ± 0.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Chronology
−485 — – −480 — – −475 — – −470 — – −465 — – −460 — – −455 — – −450 — – −445 — – P a l e o z o i c Ꞓ O r d o v i c i a n S F E a r l y M i d d l e L a t e L Stage 10 Tremadocian Floian Dapingian Darriwilian Sandbian Katian Hirnantian Rhuddanian       ← First land plant spores[1] ← Ordovician meteor event[2][3] Subdivision of the Ordovician according to the ICS, as of 2024.[4] Vertical axis scale: Millions of years ago
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	FAD of the Graptolite Nemagraptus gracilis
Lower boundary GSSP	Fågelsång section, Sularp Brook, Skåne, Sweden 55.7137°N 13.3255°E / 55.7137; 13.3255
Lower GSSP ratified	2002[5]
Upper boundary definition	FAD of the Graptolite Diplacanthograptus caudatus
Upper boundary GSSP	Black Knob Ridge section, Oklahoma, United States 34.4305°N 96.0746°W / 34.4305; -96.0746
Upper GSSP ratified	2006[6]

Naming

The name Sandbian is derived from the village Södra Sandby (Lund Municipality, Skåne County, Sweden). The name was proposed in 2006.^[8]

GSSP

The GSSP of the Sandbian is the Fågelsång section (55.7137°N 13.3255°E / 55.7137; 13.3255) 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 first appearance datum of graptolite species Nemagraptus gracilis in that section.^[9]