This article is a nice summary of the present state of our ideas about the Earth’s interior and its magnetic engine. To be totally fair, it is complete rubbish to think in terms of swirling dynamos. The core is packed and any motion must be glacial at best. Electron flow is quite a different matter. But even that requires a meaningful potential. And we already know that the mere movement of the magnetic field itself rules out the core acting like a permanent magnet.
An actual review of the global map of magnetic strength reveals a non homogenous field that still preserves the polar orientation. Sort of.
I have come to the conclusion that there exists a thin layer of (liquid) carbon between the crustal material which is disassociating and drawing contained graphitic carbon down with it before hitting the carbon melt point and then rising. The carbon must go deepest to reach a possible melt point. Or perhaps it is all graphite. The point to remember is that all other elements are dissociated there and in liquid state.
This explains how a charge of liquid carbon is able to spear its way through the crust and even reaches the surface at around seventy miles per hour. That is also fast enough to leave a little of the carbon to remain in crystal form. The rest will be consumed by the crustal material itself. Recall the known low viscosity of graphite.
This layer may only be a hundred feet thick if the average size of a kimberlite pipe is an indicator. It is certainly everywhere and about eighty miles deep. It is the slip plane between the crust and the core itself and the reason why any crustal movement is even possible at all.
The mere existence of kimberlite pipes and diamonds is proof of the existence of this layer of pure liquid carbon.
It is also a great place for storing electrons and a natural generator of a strong magnetic field that can shift and move in reaction to modest electrical or even mechanical stimulation. It likely insulates the core itself from expressing magnetic activity.
Earth's Core, Magnetic Field Changing Fast, Study Says
for National Geographic News June 30, 2008 Rapid changes in the churning movement of Earth's liquid outer core are weakening the magnetic field in some regions of the planet's surface, a new study says.
"What is so surprising is that rapid, almost sudden, changes take place in the Earth's magnetic field," said study co-author Nils Olsen, a geophysicist at the
The findings suggest similarly quick changes are simultaneously occurring in the liquid metal, 1,900 miles (3,000 kilometers) below the surface, he said.
The swirling flow of molten iron and nickel around Earth's solid center triggers an electrical current, which generates the planet's magnetic field.
The study, published recently in Nature Geoscience, modeled Earth's magnetic field using nine years of highly accurate satellite data.
Fluctuations in the magnetic field have occurred in several far-flung regions of Earth, the researchers found.
In 2003 scientists found pronounced changes in the magnetic field in the Australasian region. In 2004, however, the changes were focused on Southern Africa.
The changes "may suggest the possibility of an upcoming reversal of the geomagnetic field," said study co-author Mioara Mandea, a scientist at the German Research Centre for Geosciences in
Earth's magnetic field has reversed hundreds of times over the past billion years and the process could take thousands of years to complete.
(Related story: "Magnetic Field Weakening in Stages, Old Ships' Logs Suggest" [May 11, 2006])
Upper Atmosphere Radiation
The decline in the magnetic field also is opening Earth's upper atmosphere to intense charged particle radiation, scientists say.
Satellite data show the geomagnetic field decreasing in the South Atlantic region, Mandea said, adding that an oval-shaped area east of
"It is in this region that the shielding effect of the magnetic field is severely reduced, thus allowing high energy particles of the hard radiation belt to penetrate deep into the upper atmosphere to altitudes below a hundred kilometers (62 miles)," Mandea said.
This radiation does not influence temperatures on Earth. The particles, however, do affect technical and radio equipment and can damage electronic equipment on satellites and airplanes, Olsen of the Danish space center said.
The study documents just how rapidly the flow in Earth's core is changing, said Peter Olson, a geophysics professor at
By using satellite imagery, researchers have a nearly continuous measurement of changes, he said.
"They provide a good rationale to continue this monitoring longer," Olson said.