You almost certainly have seen a chart – Earth layers are exposed as a slightly more complicated cooked egg. The crust we live in is actually a thin shell with a hot (but still hard) shell that forms a thick layer beneath it. In the center – opposite Jules Verne – are the inner and outer core layers, which consist mainly of iron. The outer layer is the only liquid because the core is actually solid.
Although you will never forget the core, it will have a significant impact on your life. Earth's magnetic field is made up of a liquid external core convection that directs the compasses and protects us from the effects of solar wind. The history of the magnetic field of the earth is a big issue – not only because we are not really sure when the inner core has solidified.
Magnets … well, you know
There have got actually magnetic field geological records. Small magnetic mineral crystals in the cooling magma coincide with the magnetic field before freezing. This can be useful because the magnetic field of the Earth is often protruding (which means that the compass needles point to the geographical south). The orientation of these mineral needles also indicates how close they were to the equator when they were formed. This mineral trapped information was the last piece to crack the tectonic case of the plate, and it allows us to understand where each continent was in the past.
We can also work out how powerful the magnetic field is from these records. It was what the most interested team led by Richard Bono and John Tarduno at the University of Richards when they analyzed about 565 million years of rocks in Quebec.
We don't have a lot of data from this period that some researchers might suspect when the inner core finally began to harden. In this case, the researchers who studied the workers were slowly cooled down under the ground, which means that their record might cover about 75,000 years. It should be longer than the magnetic pole rotation usually takes place, so any temporary changes, for example, should be used on average.
The team found that the magnetic field was incredibly weak at the time studied. The ancient sea period has been marked by an anomalously weak magnetic field, but it was only about one fifth as strong as this period. In addition, the magnetic poles appear to be very common. It's very weird.
These data really correspond to the limited information we have from the time that is closest to this time, which is also quite odd. And the study is really interesting when comparing it with Earth's historical history simulations. Some of these simulations have predicted that the hardening of the internal kernel in geological terms was quite recent, precisely at this time. In these models, the nuclear reorganization causes the magnetic field to escape for a moment that coincides with the weakened state.
Researchers say their evidence is in line with a scenario where the internal core started to consolidate just about 565 million years ago – almost 4 billion years in Earth. It complements the question of how the magnetic field production of the "geodynamic" core looked like before this time and how it lasted. It also complements the list of weird things that happen in this Earth's history section, which involves a significant evolution of the animals' life.
In a summary attached to the paper Natural geoscienceCarnegie Science for Science researcher Peter Driscoll (who was not involved in the study) outlines the work required to perform this juicy hypothesis: “Additional palpagnetic observations, both directions and intensity are a clear next step to provide a clearer picture of the kernel state at this time. Experiments on hardening and conductivity of iron will further limit nuclear thermodynamics. Finally, the new kernel's numerical models can provide detailed predictions that check how all these components come together.
And if this time frame for internal kernel formation is correct, Driskoll writes: "The core of the inner kernel may have occurred just when you are charging the geodynamic and saving the Earth's magnetic shield."
Natural geoscience, 2019. DOI: 10.1038 / s41561-018-0288-0, 10.1038 / s41561-019-0301-2 (About DOI).