![\"Two](\"https:\/\/cdn.sci.news\/images\/enlarge13\/image_14530e-Geodynamo.jpg\")
<\/a><\/p>\nTwo enormous blobs of solid, superheated material located at the base of Earth\u2019s mantle affect the underlying liquid outer core. Image credit: Biggin et al., doi: 10.1038\/s41561-025-01910-1.<\/p>\n
Both measuring ancient magnetic fields and simulating the processes that generate them are technically demanding.<\/p>\n
To investigate these deep-Earth features, Professor Biggin and colleagues combined paleomagnetic observations with advanced computer simulations of the geodynamo \u2014 the flow of liquid iron in the outer core that generates Earth\u2019s magnetic field like a wind-turbine generates electricity.<\/p>\n
Numerical models enabled them to reconstruct key observations of the behaviour of the magnetic field seen over the past 265 million years.<\/p>\n
Even with a supercomputer, running such simulations, especially over long timescales, represents an immense computational challenge.<\/p>\n
The results revealed that the outer core\u2019s upper boundary is far from uniform in temperature.<\/p>\n
Instead, it displays strong thermal contrasts, with localized hot regions capped by the continent-sized rock structures.<\/p>\n
It also showed that some parts of the magnetic field appear to have remained relatively stable for hundreds of millions of years, while others have changed significantly through time.<\/p>\n
\u201cThese findings suggest that there are strong temperature contrasts in the rocky mantle just above the core and that, beneath the hotter regions, the liquid iron in the core may stagnate rather than participate in the vigorous flow seen beneath the cooler regions,\u201d Professor Biggin said.<\/p>\n
\u201cGaining such insights into the deep Earth on very long timescales strengthens the case for using records of the ancient magnetic field to understand both the dynamic evolution of the deep Earth and its more stable properties.\u201d<\/p>\n
\u201cThese findings also have important implications for questions surrounding ancient continental configurations \u2014 such as the formation and breakup of Pangea \u2014 and may help resolve long-standing uncertainties in ancient climate, paleobiology, and the formation of natural resources.\u201d<\/p>\n
\u201cThese areas have assumed that Earth\u2019s magnetic field, when averaged over long periods, behaved as a perfect bar magnet aligned with the planet\u2019s rotational axis.\u201d<\/p>\n
\u201cOur findings are that this may not quite be true.\u201d<\/p>\n