Earth's Core Has Another Layer, Scientists Claim

LiveScience.com ^ | 12/8/10 | Charles Q. Choi

[NormsRevenge]

What may be a new outermost layer of the Earth's core has been found, geoscientists have revealed.

This discovery could help solve mysteries of the planet's magnetic field, researchers say.

The Earth's core is composed mainly of iron, divided into a solid inner center roughly 1,500 miles (2,440 kilometers) wide covered by a liquid outer layer about 1,400 miles (2,250 km) thick. Even though the bulk of the core is iron, researchers also knew it contained a small amount of lighter elements such as oxygen and sulfur. As the inner core crystallized over time, scientists think this process forced out most of these light elements, which then migrated through the liquid outer core.

Now geoscientists think they have detected all these light elements concentrated in the outermost parts of the core.

"Ever since core structure started to be studied, there were hints of structure there — that's why we looked for it," said researcher George Helffrich, a geologist and seismologist at the University of Bristol in England.

Seismic speed changes

To investigate the core, researchers monitored seismic waves that traveled through its outer layer. The waves were generated by earthquakes in South America and the southwestern Pacific Ocean, and were recorded using arrays of seismometers in Japan and northern Europe.

The speeds at which seismic waves traveled through the outer core at different depths suggest that its composition does not remain the same all the way through. Instead, the uppermost 185 miles (300 km) or so is a distinct structure, with the section nearest the boundary consisting up to 5 percent by weight of light elements.

"The seismic structure we found is hard to deny — the signal is obvious to the eye in the data that we used," Helffrich told OurAmazingPlanet.

[Wuli]

The most plausible solution, Helffrich explained, is that expulsion of light elements from the inner core liberated what is called gravitational potential energy. As this lighter liquid rose upward, it imparted energy downward that drove the flow of metal in the core, which in turn helped keep the magnetic field running. "That fits with the wave speed profile that we observe," Helffrich said.

Then a question for those scientists might be:

If that hypothesis is proven to be correct, might it also be possible that:

a. The lighter elements in the outer layer of the core, over time, also, slowly, migrate out of the core altogether, ??? and

h. Might that migration step be part of the continuing energy imparted to the "spinning" of the core, and;

c. If that were true, then might the process that set the core spinning, one day lose 100% of the lighter elements from the core, through migration from the core, and eventually cause the core to stop spinning?

[Darksheare]

That was another horrid commercial.

[starlifter]

Yeah....it's really gonna piss off Tom Cruise.

Oh.....

Never mind.

[SunkenCiv]

Keyword: jmarvinherndon

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[SunkenCiv]

Note: this topic is from December 8, 2010. Thanks NormsRevenge.

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