May 4, 2010

Evidence Of Ancient Magnetic Field Uncovered

Scientists have uncovered evidence contained within South African rocks which shows that a weak magnetic field was present on Earth nearly 3.5 billion years ago.

The evidence in question was found inside of dacite rocks from the Barberton mountain range by University of Rochester professor John Tarduno and a team of researchers. The discovery was presented during the European Geosciences Union conference in Vienna, Austria, and was also the topic of a May 4 article by BBC News science correspondent Jonathan Amos.

"Earth's magnetic field is important to us," the professor told those in attendance at the 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."

"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," Tarduno added. "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."

Tarduno and his colleagues told Amos that they are now hoping to study volcanic rocks in Africa, India, and Australia to find evidence that the global magnetic field is older still. They believe that they could someday find evidence proving the existence of the magnetic field 3.6 to 4 billion years ago.

"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," Tarduno told BBC News. "We are developing techniques and we believe we can actually record the Earth's magnetic field in these minerals also."


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