Sandbian

EtymologyName formalityFormalUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitAgeStratigraphic unitStageTime span formalityFormalLower boundary definitionFAD of the GraptoliteLower boundary GSSPFågelsång section, Sularp Brook, Skåne, Sweden
55°42′49″N13°19′32″E / 55.7137°N 13.3255°E / 55.7137; 13.3255Lower GSSP ratified2002Upper boundary definitionFAD of the Graptolite Upper boundary GSSPBlack Knob Ridge section, Oklahoma, United States
34°25′50″N96°04′29″W / 34.4305°N 96.0746°W / 34.4305; -96.0746Upper GSSP ratified2006

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 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.