Abstract
Variations of the past geomagnetic field in the Brunhes epoch as well as during the Matuyama-Brunhes polarity transition are investigated in detail using thin sections of a deep-sea sediment core. It is revealed that the geomagnetic field oscillates with a marked decrease in intensity for an interval of about 8, 000 years during the Matuyama-Brunhes transition. A short event with reversed polarity is found in the Brunhes epoch and is presumably correlated with the earliest Biwa event occurring at an age about 0.33 m. y. BP.
