Yichang, China. It is an outcrop of the Dawan Formation. The lower boundary is defined as the first appearance of the conodont species Baltoniodus triangularis in the type section. Radiometric dating has constrained the Floian-Dapingian boundary at million years ago. The exact boundary lies 10.57 m above the base of Dawan Formation. Regional stages The Dapingian overlaps with the upper part of the Arenig, a geologic stage used in England. It is also equivalent to the lower part of the North American Whiterockian stage, most of the Baltic/Russian Volkhov stage, and the Castlemainian and Yapeenian stages which have been used in Australia and Scandinavia. References Ordovician geochronology