他们声称地球的自转和地球的磁极的关系不稳定，预示着平均每40万年就有一次的磁极颠倒。
They claim a relationship between the rotation and the magnetic polarity of Earth, which does change irregularly, with a magnetic reversal taking place every 400,000 years on average.
这种磁极颠倒在418万年前曾发生过一次，CAC地区的沉积物中就留下了这次颠倒发生过的痕迹。
One of these polarity flip-flops, known to have occurred 4.18 million years ago, left its mark in sediments in the CAC.
到底什么时候磁极将会颠倒从目前已知的证据中去预测还不能做到，但对此最适宜的猜测便是那一天的到来是好几个世纪以后的事情了。
Just when the magnetic field will flip is impossible to predict from what is known at the moment; the best guess is that there are still several centuries to go.
到底什么时候磁极将会颠倒从目前已知的证据中去预测还不能做到，但对此最适宜的猜测便是那一天的到来是好几个世纪以后的事情了。
Just when the magnetic field will flip is impossible to predict from what is known at the moment; the best guess is that there are still several centuries to go.
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