African rocks record ancient magnetic field
By Jonathan Amos | BBCNews.co.uk
Scientists have managed to push back the date for the earliest known presence of a magnetic field on Earth by about 250 million years.
The evidence is seen in tiny iron minerals that are aligned inside ancient dacite rocks from the Barberton mountains in South Africa.
Analysis of the 3.45-billion-year-old minerals indicates the strength the field was much weaker than today.
Earth’s magnetic field protects all life on the planet.
It forms a shield that deflects harmful particles from the Sun around our world, and limits the ability of this "solar wind" to erode our atmosphere.
The new work by Professor John Tarduno, from the University of Rochester, US, and colleagues has been discussed at a major Earth sciences meeting in Vienna, Austria.
"Earth’s magnetic field is important to us," Professor Tarduno told the European Geosciences Union meeting.
"[3.45 billion years ago] is a really critical time because it’s when we start seeing the first tentative signs of life, so perhaps these two things are linked together."
The Rochester team has developed techniques for studying tiny magnetite minerals trapped inside the crystals of volcanic rock.
These minerals orientate themselves with respect to the Earth’s magnetic field in a cooling magma and lock their positions once the temperature in the host rock dips below 580C.
The Barberton samples indicate the nascent field was considerably weaker than today’s protective shield.
Whereas the modern boundary between our planet’s magnetosphere and the solar wind might be located ordinarily at about 10 Earth radii, the ancient boundary would have been much closer - perhaps three to five Earth radii, said Professor Tarduno.
He explained that one likely effect of this would have been the production of polar lights, or auroras, at much lower latitudes as many more solar particles breached the shield to collide with atmospheric molecules.
It probably also meant the atmosphere lost more of its lighter elements, like hydrogen, faster than had previously been supposed, argued Professor Tarduno.
The Barberton greenstone belt preserves some of the oldest rocks on the planet.
"What that means in an evolutionary sense to us - and this is just speculation but something we want to follow it up - is that perhaps this is suggesting the Earth was much more water-rich very early on," he said.
"If, even with this magnetic field, we are losing hydrogen and water, that would suggest the palaeo-Earth in its infant state must have had more water than we think about today."
Professor Tarduno’s team is now looking back still deeper into the past for evidence of a global magnetic field.
The field is generated by convection currents in the molten-iron outer-core of the planet, and finding evidence of an even more ancient field would say much about the interior state of the young Earth.
There are volcanic rocks in Africa, India and Australia that possibly retain a record that is 3.6bn years old.
"To go back even further in time, however, we don’t have the rocks available. But what we do have is certain younger sedimentary rocks that record minerals which were eroded from more ancient rocks - as old as four billion years old," Professor Tarduno told BBC News.
"We are developing techniques and we believe we can actually record the Earth’s magnetic field in these minerals also."
Article from: news.bbc.co.uk
2012: Leaks Found in Earth’s Magnetic Field
Video from: YouTube.com
Origin of Earth’s Magnetic Field
Video from: YouTube.com
Also tune into:
Walter Cruttenden - Lost Star of Myth and Time, Rise and Fall of Civilization and Consciousness
Walter Cruttenden - Sirius, The Binary Star & Precession
Rens van der Sluijs - Plasma Mythology & The Axis Mundi
Wallace Thornhill - The Electric Universe
William Henry - The Apotheosis is at Hand, NWO, COP15, Norway Blue Spiral & Stargates
Edmund Marriage - Global Catastrophe, Restart of Civilization & The Anu-Nagi (The Shining Ones)
Earth’s Magnetic Field - Wikipedia
Earth’s Magnetic Field Is 3.5 Billion Years Old
Intro to magnetic fields - What is the structure of the Earth’s magnetic field?
Magnetite - Wikipedia
Henges: Stonehenge, Woodhenge, Avebury & Stanton Drew (Video)
Moral judgments can be altered ... by magnets
Earth’s north magnetic pole racing towards Russia due to core flux
Nathan Stubblefield and Electromagnetism
Russians order Flight Changes, after Massive Magnetic Shift downs Airliners
Playing the Field: Geomagnetic Storms and the Stock Market
’Hidden Portal’ Concept Described: First Tunable Electromagnetic Gateway
Chris Dunn & Great Pyramid 3D Electromagnetic Power Plant Walkthrough (Video)
Oceans charge up new theory of magnetism
Mayan Calendar & Human DNA II - Prophesies & Sun Magnetic Reversals - part 1 (Video)
Sweet dreams are made of geomagnetic activity
Magnetic Portals Connect Sun and Earth
Phoenix Pole Shift
Latest News from our Front Page
As Greece Falls, Will Those With Gardens Survive?
Greeks don't want austerity, but the future is bleak and unknown.
As of Friday, grocery shelves were being stripped bare of staple cooking goods, and pharmacies ran out of crucial medicines like thyroxine (thyroid treatment). More than half of those items are imported, but with banking plugs, companies are unable to pay suppliers. Things are frozen; stopped, and tens of thousands ...
Rise of the super soldier: Liquid armour, indestructible exoskeletons and weapons that never miss revealed as the future of warfare
War has been one of the greatest spurs to science in history.
Developments as diverse and far-reaching as space travel, superglue, duct tape and microwaves owe their origins beneath camouflage netting and behind sandbags.
Today's military innovations, though, are focused not just on getting the job done, but doing so as quickly as possible and bringing the soldiers home to their ...
Europe Survived War And Depression: Can She Survive Invasion?
However the Greek crisis ends, whether with Athens leaving the Eurozone, or submitting and accepting austerity at the dictates of its creditors, the European Union appears headed for an existential crisis.
Greece borrowed and spent beyond its means, like New York City in the ’70s, and Detroit, Illinois, and Puerto Rico today. But the crisis of Europe is about more than ...
Professor: Reason Itself Is A White Male Construct
A philosophy and religion professor at Syracuse University gave an interview to The New York Times Thursday in which he critiqued the notion of pure reason as simply being a “white male Euro-Christian construction.”
Prof. John Caputo was being interviewed by fellow philosophy professor George Yancy for the 13th installment of an interview series Yancy conducts with philosophers regarding racial topics.
Given its emphasis on first principles ...
The Broken Window Fallacy
Youtube description: This short video explains one of the most persistent economic fallacies of our day.
|More News » |