The final normal polarity chron in the Quaternary, preceded by the Matuyama, and radiometrically dated from 0.78 Ma ago to the present. The Brunhes chron contains several brief reversed polarity subchrons of which the Blake (c.110  000 years BP), Lake Mungo (c.30  000 years BP), Laschamp (c.18 000 years BP), and Gothenburg (c.13  000 years BP) are the best, but still poorly, established.