After the end of World War II, people's marine exploration technology has been greatly improved, and high-sensitivity magnetic detectors have been developed and applied to marine surveys. Lamont Institute of Geology and Scripps Institute of Oceanography of Columbia University took the lead in this research. Geologists from these two institutes cooperated with each other, and spent nearly 10 years from10, using towed magnetometers, sailing back and forth for nearly 20 voyages on the sea surface of the mid-Atlantic ridge to conduct paleomagnetic investigation. After that, another American marine survey ship, Pioneer, with the support of the American government, used all-magnetic magnetometers to conduct paleomagnetic surveys of specific Pacific waters with dense survey lines and stations. These two investigations have enabled people to obtain more systematic magnetic data of large-area oceanic crustal rocks. Scientists will compare and analyze the obtained paleomagnetic data, and then draw the seabed rocks with the same magnetic strength on the map with isolines. So, people are surprised to find that most of these equipotential lines are parallel to both sides of the mid-ocean ridge in the north-south direction, and their magnetism is positive and negative. Each one is about hundreds of kilometers long and dozens of kilometers wide. The submarine magnets with high magnetization form a positive magnetic stripe, and the adjacent submarine magnets with weak magnetization form a negative magnetic stripe. The magnetic strips distributed at the bottom of the ocean are like magnetized submarine rocks. The discovery of submarine magnetic belt became a great miracle of geoscience research at that time, and its genetic mechanism was also a topic of discussion.

The discovery of submarine magnetic belt has aroused great interest of geologists all over the world. People have put forward various hypotheses about the formation mechanism of submarine magnetic stripe. Among many hypotheses, the most representative are two scholars from Cambridge University in England, one is vanity and the other is Matthews. The hypothesis of submarine magnetic tape origin put forward by these two scholars is still accepted and recognized by most geologists.

Since 1963, Vain and Matthews have studied a lot of data of submarine magnetic belt, trying to find out the genetic mechanism and geological significance of submarine magnetic belt. Before they engaged in this research, the theory of submarine expansion had been initially formed in the field of geoscience research, especially the theory of "Geott" (flat-topped seamount) put forward by the famous geologist Hess, which provided strong evidence for the theory of submarine expansion. Wei Gena's continental plate theory, which was put forward earlier, resurfaced after being neglected for a period of time. In this context, two British scholars linked their research with the theory of submarine expansion, trying to explain the theory of submarine expansion from the perspective of paleomagnetism. Vain and Matthews believe that the appearance of submarine magnetic stripe is not caused by uneven magnetization, but is formed under the background that the geomagnetic field turns for some reason. When new submarine rocks are formed in the mid-ocean ridge, if the geomagnetic field is in the positive direction at that time, then a positive lithologic magnetic stripe can be obtained; Otherwise, the opposite lithologic magnetic stripe is obtained. That is to say, due to the expansion of the seabed, the seabed rocks with positive direction will be pushed to both sides by the new rocks formed later; If we are in the geological period of anti-geomagnetic field at this time, the rocks formed will of course have anti-magnetism. During the geological evolution of the earth, the geomagnetic field has turned many times, with the formation and expansion of new oceanic crust along the mid-ridge. This has left a series of magnetic strips with opposite magnetization directions on today's ocean crust. Judging from the distribution of submarine magnetic strips, every time the geomagnetic field turns, it will leave magnetic marks on the newly formed seabed at that time. In other words, the submarine magnetic tape can actually be regarded as a historical record of the continuous rotation of the earth's magnetic field.

On the other hand, if the continents in the world have not moved since ancient times, then only one magnetic pole migration line can be left on the earth. But geological data tell people that there are many magnetic migration lines with different polarities. Through technical means, people have measured the migration line of the north magnetic pole in North America and Europe respectively. Although North America and Europe are far apart, the migration lines of magnetic poles are very similar and almost parallel. If we want to merge them into a line, we only need to move the North American continent eastward for 3000 kilometers, so that the two continents can be connected to form a complete continental plate. This continent lies right in the Atlantic Ocean today.