Copied from General Geology, chapter, “Continental Drift,” by Robert J. Foster. Copyright 1969, by Charles E. Merrill Publishing Company, Columbus, Ohio.
The earth’s magnetic field is believed to originate from electric currents in the core. It is a well-known law in physics that moving current creates a magnetic field, and conversely, a currents induced into a conductor moving in a magnetic field. Electrical currents in the core could start in a number of ways, such as through a weak battery action caused by compositional differences.
Once started, these currents could be amplified by a dynamo actioning the Earth’s core. A dynamo produces electric current by moving a conductor in magnetic field. In the earth the core is the conductor, and because it is fluid, it can move. The mechanism envisioned is similar to a dynamo, which produces an electric current, and this current is fed to an electric motor that drives the dynamo. Friction and electrical resistance would prevent such a perpetual motion machine from continuing to operate unless more energy is added.
In the earth this additional energy can come from movement of the fluid core. Calculation shows that very little additional energy needs to be added in the case of the earth; and the necessary energy for core motion, probably in the form of convection, could come from many sources. Thus a current is somehow started in the Earth’s core, and this current produces a magnetic field. The conducting core moves through the magnetic field, and a current is induced in this part of the core, starting the whole process over. In a stationary earth, the movements of the core would probably be more or less random and the magnetic fields produced would probably cancel each other.
The rotation of the earth tends to orient the motions of the core so that the motions and,therefore, the currents are in planes perpendicular to the rotational axis, Viewed from outside the earth, the overall current produced would be parallel to latitudes. Such currents produce a dipole magnetic field red on the rotational axis. A field produced in this way would have all of the characteristics of the Earth’s magnetic field. The main field would be a dipole field; superimposed on this would be other fields caused by variations in the core’s motion.
This can account for the variations in intensity and location of the Earth’s field. The Earth’s dipole field does not coincide with its rotational axis, however, as this theory predicts, although if averaged over a long enough period, the dipole field would perhaps appear centered on the rotational axis.The positions of the magnetic pole deduced from remnant magnetism of Pleistocene and younger rocks cluster around the rotational axis, suggesting that this is true. The present [in 1969] dipole field is 11.5 degrees from the rotational axis and lies northwest of Greenland, some distance from the magnetic north pole, north of Canada. End of copied Material.
If one side of the Earth faced the Sun for the first nine-tenths of Earth History, then we can forget about claims that the Earth’s Magnetic Fields somehow mysteriously generated inside the Earth. Scientists believed, until the Mariner 10 Spacecraft proved them wrong, that Mercury could not have magnetic field, because it revolved too slowly. They thought until about 1965 that one side of Mercury always faced the Sun. Actually, Mercury revolves around the Sun every 88 days, and rotates once every 58.6 days. It rotates three times, while orbiting twice around the Sun.
I never did believe that malarkey, about the Earth’s core being a dynamo anyway, it sounded too much like Venus, to me. I guess though, when you already have continent-eater inside the Earth, conjuring up dynamo, and the power to energize it, are small potatoes.
The following is a lame attempt to explain Mercury’ magnetic Field. The paragraph below is copied from: “The Cambridge Encyclopedia of Earth Sciences” Chapter 37, “The geology of the solar system.” Published jointly by: Crown Publishers Inc. One Park Avenue, New York N.Y. & Cambridge University Press, 32 East 57 Street, New York, N. Y.
Mercury’s magnetic field.
The Mariner 10 spacecraft revealed that Mercury has magnetic field with an intensity of only about 1/100 that of the Earth, with north and south poles closely aligned with the rotational axis. This discovery was not anticipated because it was considered that Mercury’s slow period of rotation would preclude the operation of a geomagnetic dynamo similar to the Earth’s. As suggested in the case of the Moon’s field it is possible that Mercury’s magnetic field is essentially a fossil one acquired early in its history and never subsequently lost. Since Mercury is so close to the Sun it seems almost certain that it must have been affected by the Sun’s powerful field. End of copied material.
All of the magnetic fields
that I know of, and understand, were initiated by electric energy. You can magnetize a screwdriver by simply wrapping insulated wire around it a half dozen times, and arcing [momentarily touching the positive and negative anodes with the ends of the wire] on a twelve-volt battery. Logically, we should expect that the driving forces that maintain the Earth’s Magnetic Field should be just as easily explained. Granted, the Earth's Magnetic Field is a whole lot larger than the magnetic field surrounding the end of a screwdriver. But the principle, and the "Laws Of Physics" which account for their existence, are exactly the same. The odds greatly favor the probability that the driving force behind the Earth’s Magnetic Field arrives on Earth via the Solar Wind, or at least, along with the Solar Wind. More than 99 percent off all energy in the entire Solar System, originates in/on the Sun.
Electricity does not like heat. Or rather, heat increases resistance to the flow of electricity, in any material. For example; the hotter an electrical wire is, the less amperage it will carry. Actually, the very thought of moving electricity though anything, as hot as the center of the Earth, much less generating electricity in that environment, is preposterous. Any electrical energy emitted by the Sun, and attracted to the Earth’s mass, would move through the cool upper strata, circling the Earth’s molten interior and hot core.
In all probability, the Earth’s Magnetic Field is powered by electrical energy emitted by the Sun. This atomically generated electrical energy is probably nearer akin to Static Electricity than any other known form of energy. Think of this energy being constantly, lightly sprinkled on the side of Earth facing the Sun, like some slow, steady electrical rain. But this electricity does not spread, or run around the Earth at the speed of light, like electricity in a power-line. It accumulates in receptive areas until it accrues enough charge, to motivate it moving onto an adjacent area with a lesser charge.
There it charges until it has enough charge to move on again, and so on, and on, until it has circled the Earth. Before the Earth started turning once a day as it does now, electrical energy which was attracted to the Earth’s mass, moved from the Sunny Hemisphere around the Earth and was eventually emitted from that point on Earth, which was furthest from the Sun, back out into the Solar Wind. Later; when the Earth’s Magnetic Field began to materialize that point become the North Magnetic Pole. This consent movement of electricity from the vicinity of what became the South Magnetic Pole, to the North Magnetic Pole instigated, oriented and maintained the Earth’s primeval Magnetic Field.
This explains why the locations of the primeval magnetic poles, were those two points on Earth, which were the closest, and the furthest, from the Sun. Once the Earth started to spin, most of the electrical rain descended, like the Sun’s life-sustaining rays, on the equatorial regions. Very little to none reach the North or South Rotational Axis Poles. Therefore, the receptive areas in the equatorial region began to bleed off their charges to those areas that were closer to the Rotational Axis Poles. Soon energy from the equatorial regions, around the World began to migrate toward the Rotational Axis Poles.
Once said flow of energy became established, it redirected the Earth’s Magnetic Field, aligning it with the Earth’s Rotational Axis. Why the North Rotational Axis Pole, also became the North Magnetic Pole is a little harder to explain. With all things being equal, the South Rotational Axis Pole had a fifty-fifty chance of becoming the North Magnetic Pole. There are those who claim that the North and South Rotational Axis Poles divide up the honor of hosting the North Magnetic Pole.
They maintain that the positive and negative magnetic poles, switch places periodically, kind of similar to alternating current. As previously addressed, the theory of the poles switching, more than a hundred times, sounds like a vacuous deduction, to me. It was made up by the same people that deduced the continents on this Earth are floating around like so many rafts in a hurricane.
It does appear that the North Magnetic Pole could be at/near the North Rotational Axis Pole, just by chance. It is also possible that because of the larger land masses in the Northern Hemisphere, it attracted more electrical energy than the Southern Hemisphere, and therefore, became sated and began to emit energy back into the jet stream first.
Once the flow of electrical energy from the North Hemisphere started, the energy south of the Equator would have followed, and set the stage to redirect the Earth’s Magnetic Field, and align it with the Northern Axis Pole. Whether the Earth’s Magnetic Field maintained its integrity, while it rotated ninety degrees to align with the Earth’s Rotational Poles, or was extinguished when the Earth suddenly started to spin,and regenerated, and aligned with the Rotational Poles, is a real poser. Whichever scenario is true, the realignment undoubtedly took place in a month, more likely in matter of days.
On a geological timescale, that is a blink of an eye. Not nearly time enough, to expect that any appreciable evidences would ever be found under normal circumstances, to shed any light on the event. But the Dinosaur Era ended during the most catastrophic event the continents on this Earth have ever suffered, so there may be some evidence surface indicating how the Earth’s Magnetic Field reacted during these violent times. There is no doubt that erupting volcanoes, magma flows and many horrific earthquakes marked the time.
Remember: On a globe; I drew two circles,covering the Pacific Ocean, then drew a common bisector across where those circles overlapped, to find the original location of the Earth’s Equator. Finding the center of that segment of the equatorial line, gave me the point on Earth furthest from the Sun, and I then drew a perpendicular line through that point. It was a simple matter then to extend the Equator, and the perpendicular line, on around the globe. At that point where the perpendicular line re-crossed the Equator, was the center of the Sunny Hemisphere. Said perpendicular line also bisected the Earth, and the two points furthest from the Equator on that bisector, marked the sites of the original Rotational Axis Poles.
The above was reiterated to establish that the two points on Earth, which are furthest from and nearest to the Sun, the sites of the original North and South Magnetic Poles, and the sites of the North and South Rotational Axis Poles, were objectively located, by geometric calculation.
That point is important. Because if we chart the movement of the North Magnetic Pole, from the original site on the Equator in the middle of the Pacific Ocean, to the original site of the Rotational Axis Pole, and then to the present Rotational Axis Pole, it parallels the route scientists charted via paramagnetic studies.
Copied from Introduction to Geology, Copyright 1968, by Prentice-Hall Inc. Englewood Cliffs, NJ. [Cox's Statement]
Paleomagnetic measurements of rocks from North America and Europe show the paths followed by the magnetic poles of these two continents from Precambrian times to the present. [Redrawn from Cox and Doell]
End of Copied text.
Copied from “Physical Geology,”
copyright 1969, by John Wiley &
Sons Inc. New York, London, Sidney. Cox's Statement:
Curves that trace the inferred path followed by the North Magnetic Pole through time, based on paleomagnetic measurements in North America (blue curve) and Europe (black curve). After Eocene time the two curves merge.
(After Northrop and Meyerhoff, 1963 based on Cox and Doell, 1960.) End of copied text.
Please note; how the location of the North American and European paths, have been switched on these maps. The “Introduction to geology” map has the American path on the inside, as the paths converge. On this map from the: “Physical Geology,” forth edition, copyright 1971, by Prentice-Hall Inc. Englewood Cliffs, New Jersey, it is on the outside. A sceptic might wonder if they may have intentionally switched the paths so they could add the following paragraph.
Copied notation, concerning this map.
Polar wandering support’s continental drift. The most logical explanation is based on the interpretation that Earth’s magnetic field has remained an axial dipole and that only one north magnetic pole existed. The divergence in reconstructed positions of this pole could have resulted from progressive drift of the two continents away from each other. Ancient proposition's reconstructed from the two continents can be made to coincide closely if drift is assumed and if the continents are moved back to the positions they are thought to have occupied before the drift began. End of copied text.