What lies thousands of kilometers beneath our feet?<\/h2>\n\n\n\n
Deep inside the planet, Earth has a thin, solid crust, a thick, rocky mantle, a liquid outer core, and a solid inner core. Humans have drilled only a little more than 7 miles down<\/a>, so scientists mostly rely on seismic waves and other measurements to infer what happens in these layers.<\/p>\n\n\n\n At the base of the mantle, about 2,900 kilometers below the surface, lie two continent-sized rock piles beneath Africa and the Pacific Ocean that appear hotter than the surrounding mantle. <\/p>\n\n\n\n These giant “blobs” sit on top of the liquid outer core, where variations in heat flow help drive churning motions in the molten metal that power the geodynamo and keep the planet from becoming magnetically quiet like Mars and Venus.<\/p>\n\n\n\n When lava erupts at the surface and cools, tiny crystals rich in iron line up with the local magnetic field. Once the rock solidifies, those crystals lock in a magnetic signal<\/a> that preserves the direction and strength of the field at that place and time.<\/p>\n\n\n\n In the new work, researchers analyzed magnetic directions recorded by igneous rocks that formed over roughly the last 250 million years and noticed something odd. <\/p>\n\n\n\n As expected, the directions changed with latitude, but they also showed a clear pattern with longitude, with rocks formed above one deep mantle region tending to record different directions than those formed above the other.<\/p>\n\n\n\n To test whether the hidden blobs could explain this pattern, the team built computer simulations of the geodynamo<\/a> that track the flow of liquid iron in the outer core and the magnetic field it generates over tens of millions of simulated years. When the simulations assumed that heat left the core at the same rate everywhere, the modeled field looked either too simple or too chaotic compared with the rock record.<\/p>\n\n\n\n The picture changed when the researchers let heat escape less efficiently beneath the hot blobs and more efficiently beneath cooler regions of the mantle. Under those conditions, the simulations produced long-lived structures in the magnetic field that closely resembled the signals seen in ancient rocks and were less likely to collapse into weak, unstable states, and lead author Andy Biggin from the University of Liverpool said in a university statement that “these findings suggest that there are strong temperature contrasts in the rocky mantle just above the core”.<\/p>\n\n\n\n The study supports a view that the lower mantle does not insulate the core in a uniform way but instead acts more like a patchwork blanket, with the giant hot blobs restricting heat loss in some places and cooler regions allowing the core to shed heat more quickly. <\/p>\n\n\n\n Over long timescales, that uneven pattern seems to have helped keep Earth’s magnetic shield<\/a> stable and strong, limiting the number of times the field falls into weak, multipolar states that would let more charged particles from the Sun reach the atmosphere and could threaten satellites and modern power grids.<\/p>\n\n\n\n The findings also challenge the textbook idea that the time averaged magnetic field behaves exactly like a perfect bar magnet aligned with Earth’s spin axis. As Biggin put it, “our findings are that this may not quite be true”, and the field instead carries a subtle imprint of the deep mantle structures and of how heat leaves the core, echoing earlier research that linked lower mantle heat flow to long-lived bands in the magnetic field.<\/p>\n\n\n\n The main study was published in Nature Geoscience<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" Most of us only think about Earth’s magnetic field when a compass points north or the aurora lights up the … <\/p>\nRead More: Goodbye to seasonal viruses as we know them: the first universal vaccine against respiratory infections and allergies is now closer than ever<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
Reading Earth’s ancient magnetic memory<\/h2>\n\n\n\n
![\"World](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/04\/earth-deep-mantle-blobs-africa-pacific-map.jpg\" "\\"\\"")
Supercomputer models of a churning metal core<\/h2>\n\n\n\n
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Why deep mantle blobs matter at the surface<\/h2>\n\n\n\n
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