The quaternary period of geologic time extends from the end of the tertiary period to the present. 地质时期中的第四纪是从第三纪一直到现在。
Although magnetic reversals have occurred many times in the geologic past, it is not yet possible to predict when the next reversal will occur. 尽管在过去地质时期地磁场发生了多次倒转,但要预测下次倒转将在何时发生也还是不可能的。