News Excerpt:

Geologists at MIT and Oxford University have found ancient rocks in Greenland that bear the oldest remnants of Earth’s early magnetic field.

More about the Study:

• 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 represent some of the earliest evidence of a magnetic field surrounding the Earth. 
• The researchers suspect that an early magnetic field played a critical role in making the planet habitable by retaining a life-sustaining atmosphere and shielding the Earth from damaging solar radiation.
• The objective of the researchers was to find rocks that still held signatures of the Earth’s magnetic field when the rocks first formed, 
• The team sampled rock formations in the Isua Supracrustal Belt in southwestern Greenland.
• The researchers carefully sampled banded iron formations, which are rock types like stripes of iron-rich and silica-rich rock 
• Researchers suspect that the rocks formed in primordial oceans before the rise of atmospheric oxygen around 2.5 billion years ago.
• Through careful analysis using uranium-lead ratios and re-magnetization techniques, the team concluded that the rocks likely harboured this ancient 3.7-billion-year-old magnetic field.