Answer:
Areas where the rocks have a reversed polarity
Explanation:
The rocks are an excellent natural indicator about the past of the magnetic field of the Earth and its changes. This is due to the direction of the metallic crystals, which always point toward the strongest pole. While in the present, the North Pole is the one that has the stronger magnetic field, it has not been like that always in the past, but there has been periods when the South Pole has been the stronger one. This can be seen by some rock samples found in the oceans, as their crystals are pointing toward what is now the South Pole, not as the newer rocks that point toward the stronger North Pole, meaning that the South Pole had the stronger magnetic field in certain periods of the past, which can be determined by the age of the rocks.
