Geologists at MIT and Oxford University have found ancient rocks in Greenland that bear the oldest remnants of Earth’s early magnetic field. The researchers determined that the rocks are about 3.7 billion years old and retain signatures of a magnetic field with a strength of at least 15 microtesla. The ancient field is similar in magnitude to the Earth’s magnetic field today.
The results of the study published in the Journal of Geophysical Research, represent some of the earliest evidence of a magnetic field surrounding the Earth. Previous studies have shown evidence for a magnetic field on Earth that is at least 3.5 billion years old. The new study is extending the magnetic field’s lifetime by another 200 million years.
“If the Earth’s magnetic field was around a few hundred million years earlier, it could have played a critical role in making the planet habitable,” Benjamin Weiss from the Department of Earth, Atmospheric and Planetary Sciences at MIT and one of the authors told MIT News.
