众所周知，地球的磁场周期性地向相反的方向改变自己的方向。由于岩石中含有磁性矿物，这种转变可以测定。例如，在海洋的线性磁异常中反映了岩浆岩的喷发序次：在形成年轻地壳区段的凝固熔岩中，所含的金属保存了熔岩喷发时期的地球磁场方向。测定了海底交替磁条带的年龄后， It is well known that the Earth’s magnetic field periodically changes its direction in the opposite direction. Since rocks contain magnetic minerals, this shift can be measured. For example, the linear magnetic anomalies of the ocean reflect the eruption sequence of magmatic rocks: the metal contained in the solidified lava forming the young crustal section retains the direction of the earth’s magnetic field during lava eruptions. After determining the age of the alternating magnetic stripes on the sea floor,