We have recently
discovered that the core is actually rotating at a slightly different
speed than the crust. This is very good news for my crustal shift
conjecture that was involved with the Pleistocene Nonconformity. I
had no difficulty in explaining how it could move at the contact
horizon with molten elemental carbon providing a thin slip layer some
hundred meters thick and demonstrated in the geological record by the
genesis of diamonds. I still had no demonstration that it did move.
Now we know that it is moving continuously anyway removing that
objection.
Thus impacting a comet
on the north Polar Region becomes precisely predictable in terms of
its effect of crustal momentum. This is very good news as it makes
such an attempt more than simply realistic, it even makes it
practical if it addresses a need such as ending the great northern
Ice Age.
Recall that the Ice
Age was ended by rotating the crust through thirty degrees along an
arc from the North Pole to the center of Hudson Bay. This had the
immediate effect of moving the Gulf of Mexico south thirty degrees
and placing a huge body of water into the tropics. This then powered
up the Gulf Stream to pump warm water north into the Arctic. The
impact really had to be precise.
In the event, we now
know that the two layers are not directly attached to each other and
are in fact in motion relative to each other.
The Enigma 1,800
Miles Below Us
DEEP THOUGHTS Jules
Verne's classic "A Journey to the Center of the Earth" has
inspired several film versions, including one in 2008.
By NATALIE ANGIER
Published: May 28,
2012
As if the inside story
of our planet weren’t already the ultimate potboiler, a host of new
findings has just turned the heat up past Stygian.
Geologists have long
known that Earth’s core, some 1,800 miles beneath our feet, is a
dense, chemically doped ball of iron roughly the size of Mars and
every bit as alien. It’s a place where pressures bear down with the
weight of 3.5 million atmospheres, like 3.5 million skies falling at
once on your head, and where temperatures reach 10,000 degrees
Fahrenheit — as hot as the surface of the Sun. It’s a place where
the term “ironclad agreement” has no meaning, since iron can’t
even agree with itself on what form to take. It’s a fluid, it’s a
solid, it’s twisting and spiraling like liquid confetti.
Researchers have also
known that Earth’s inner Martian makes its outer portions look and
feel like home. The core’s heat helps animate the giant jigsaw
puzzle of tectonic plates floating far above it, to build up
mountains and gouge out seabeds. At the same time, the jostling of
core iron generates Earth’ magnetic field, which blocks dangerous
cosmic radiation, guides terrestrial wanderers and brightens northern
skies with scarves of auroral lights.
Now it turns out that
existing models of the core, for all their drama, may not be dramatic
enough. Reporting recently in the journal Nature, Dario Alfè of
University College London and his colleagues presented evidence
that iron in the outer layers of the core is frittering away heat
through the wasteful process called conduction at two to three times
the rate of previous estimates.
The theoretical
consequences of this discrepancy are far-reaching. The scientists say
something else must be going on in Earth’s depths to account for
the missing thermal energy in their calculations.
They and others offer
these possibilities:
¶ The core holds a
much bigger stash of radioactive material than anyone had suspected,
and its decay is giving off heat.
¶ The iron of the
innermost core is solidifying at a startlingly fast clip and
releasing the latent heat of crystallization in the process.
¶ The chemical
interactions among the iron alloys of the core and the rocky
silicates of the overlying mantle are much fiercer and more energetic
than previously believed.
¶ Or something novel
and bizarre is going on, as yet undetermined.
“From what I can
tell, people are excited” by the report, Dr. Alfè said. “They
see there might be a new mechanism going on they didn’t think about
before.”
Researchers elsewhere
have discovered a host of other anomalies and surprises. They’ve
found indications that the inner core is rotating slightly faster
than the rest of the planet, although geologists disagree on the size
of that rotational difference and on how, exactly, the core manages
to resist being gravitationally locked to the surrounding mantle.
Miaki Ishii and her
colleagues at Harvard have proposed that the core is more of a
Matryoshka doll than standard two-part renderings would have it. Not
only is there an outer core of liquid iron encircling a Moon-size
inner core of solidified iron, Dr. Ishii said, but seismic data
indicate that nested within the inner core is another distinct layer
they call the innermost core: a structure some 375 miles in diameter
that may well be almost pure iron, with other elements squeezed out.
Against this giant jewel even Jules Verne’s middle-Earth mastodons
and ichthyosaurs would be pretty thin gruel.
Core researchers
acknowledge that their elusive subject can be challenging, and they
might be tempted to throw tantrums save for the fact that the Earth
does it for them. Most of what is known about the core comes from
studying seismic waves generated by earthquakes.
As John Vidale of the
University of Washington explained, most earthquakes originate in the
upper 30 miles of the globe (as do many volcanoes), and no seismic
source has been detected below 500 miles. But the quakes’ energy
waves radiate across the planet, detectably passing through the core.
Granted, some temblors
are more revealing than others. “I prefer deep earthquakes when I’m
doing a study,” Dr. Ishii said. “The waves from deep earthquakes
are typically sharper and cleaner.”
Dr.
Ishii and other researchers have also combed through seismic data
from the human equivalent of earthquakes — the underground testing
of nuclear weapons carried out in the mid- to late 20th century. The
Russian explosions in particular, she said, “are a remarkably
telling data set,” adding that with bombs, unlike earthquakes, the
precise epicenter is known.
Some researchers seek
to simulate core conditions on a small, fleeting scale: balancing a
sample of iron alloy on a diamond tip, for example, and then
subjecting it to intense pressure by shooting it with a bullet.
Others rely on complex computer models. Everybody cites a famous
paper in Nature in 2003 by David J. Stevenson, a planetary scientist
at Caltech, who waggishly suggested that a very thin, long crack be
propagated in the Earth down to the core, through which a probe in a
liquid iron alloy could be sent in.
“Oh, the things we
could learn, if only we had unlimited resources,” Dr. Ishii sighed.
The core does leave
faint but readable marks on the surface, by way of the magnetic field
that loops out from the vast chthonic geodynamo of swirling iron,
permeating the planet and reaching thousands of miles into space.
Magnetic particles trapped in neat alignment in rocks reveal that the
field, and presumably the core structures that generate it, has been
around for well over 3 billion of Earth’s 4.5 billion years.
For reasons that
remain mysterious, the field has a funny habit of flipping. Every
100,000 to a million years or more, the north-south orientation of
the magnetosphere reverses, an event often preceded by an overall
weakening of the field. As it turns out, the strength of our current
north-pointing field, which has been in place for nearly 800,000
years, has dropped by about 10 percent in the past century,
suggesting we may be headed toward a polarity switch. Not to worry:
Even if it were to start tomorrow, those of us alive today will be so
many particles of dust before the great compass flip-flop is through.
The portrait of the
core emerging from recent studies is structured and wild, parts of it
riven with more weather than the sky. Earth assumed its basic layered
effect as it gravitationally formed from the rich, chunky loam of the
young solar system, with the heaviest ingredients, like iron and
nickel, migrating toward the center and lighter rocky material
bobbing above.
Traces of light,
abundant elements that bond readily with iron were pulled coreward,
too, and scientists are trying to figure out which mix of oxygen,
sulfur or other impurities might best match the seismic data and
computer models. Distinct boundaries of state or substance
distinguish the different layers — between the elastic rock of the
mantle and the iron liquid of the outer core, and between the liquid
outer core and the solid inner core.
The core accounts for
only one-sixth of the volume of the Earth but one-third of its mass,
the great bulk of iron maintained in liquid form by the core’s
hellish heat. “Liquid” in this case doesn’t mean molten like
lava. “If you could put on your safety gloves and stick your hands
into the outer core, it would run through your fingers like water,”
said Bruce Buffett, a geologist at the University of California,
Berkeley.
“The viscosity is so
low and the scale of the outer core so large,” Dr. Buffett added,
“that the role of turbulence is a relevant feature in how it flows.
Think planetary atmosphere, or large jet streams.” Only in the
inner core does pressure win out over temperature, and the iron
solidify.
The core’s thermal
bounty is thought to be overwhelmingly primordial, left over from the
planet’s gravitational formation and mostly trapped inside by the
rocky muffler of the mantle. Yet as the hot Earth orbits relentlessly
through frigid space, the core can’t help but obey the second law
of thermodynamics and gradually shed some of its stored heat.
The heat can be
transferred through two basic pathways: conducted straight outward,
the way heat travels along a frying pan, or convected out in plumes,
the way hot air rises in the atmosphere or soup bubbles in a pot.
Conduction is
considered a wasted or even boring form of energy transfer — heat
moves, but the Earth does not. Convection, by contrast, is
potentially industrious. Convection currents are what ripple through
the mantle and shuffle around the tectonic plates, and convection
stokes the geodynamo that yields our switching field.
In their report in
Nature, Dr. Alfè and his colleagues used powerful computers and
basic considerations of atomic behavior to calculate the properties
of iron and iron alloys under the presumed conditions of the core.
They concluded that the core was losing two to three times as much
heat to conduction as previously believed, which would leave too
little thermal energy to account for the convective forces that power
the Earth’s geodynamo. Hence the need to consider possible sources
of additional heat, like stores of radioactive potassium or thorium,
or a fast-crystallizing inner core.
Dr. Buffett suggests
that water on the surface may also help Earth balance its thermal
budget, — by slightly weakening the Earth’s rocky plates and
making them more readily churned and recycled in a vigorous,
sustainable convective stew.
Life needs water, and
maybe its planet does, too.
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