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A tree - ringed African lake has yielded a criminal record of Earth ’s magnetic field sweep the retiring 150,000 years .
A core of rock and sediment drilled from the bottom of Lake Chala , a picturesque crater lake on the border of Tanzania and Kenya , contains records of the wobbles in the satellite ’s magnetic field . This rock also contains worthful data about the climate over the past 150,000 class , when innovative mankind were flow out of Africa , into the Arabian Peninsula and forward to Europe and Asia .
Scientists drilled samples from the bottom of Lake Chala (pictured above) to reveal clues about Earth’s climate over the past 150,000 years.
" There is an effort to attempt to translate what term drive [ humans ] to leave Africa and go inhabit the residual of Eurasia , " saidAnita Di Chiara , a paleomagnetist at Italy ’s National Institute of Geophysics and Volcanology in Rome . To utilize ancient deposit phonograph record to construct the past climate , though , " we need ages , " Di Chiara told Live Science . " We involve a mode to date these sediment . "
That ’s where the version in Earth ’s magnetic athletic field come in . When rocks shape , they engage in a record of the magnetic field via lowly magnetised crystals that align with the field at that prison term . Most of these rock records come from near the perch , where these signal are stronger , Di Chiara said . " Getting an equatorial record is kind of special , " she said .
scientist like Di Chiara can liken the magnetic changes in rock layers from one location , like Lake Chala , to layer around the world where researchers already know how previous the rocks are . They can also use layers in the rock from known events to calibrate the datum . For example , the nitty-gritty from Lake Chala includes an ash layer from theToba supervolcano , which erupted in Indonesia 74,000 years ago .
Lake Chala is a special place to get this sort of data , Di Chiara said . It ’s a crater lake fed by runoff from the surrounding cliff and forests , not from declamatory streams or river . That entail the layers at the bottom of the lake are n’t mixed up by one - off event , like floods . alternatively , the level are pile neatly , season by time of year .
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The investigator found six magnetic excursion — temporary , sometimes localized fluctuations in the charismatic field — in the 150,000 - year disk , they reported in April in the journalGeochemistry , Geophysics , Geosystems . One was an anomaly not see elsewhere in the rock ‘n’ roll record , Di Chiara said . Such excursions may be because of chaotic circulation in Earth ’s inner core or by interactions between the self-colored inner center and the liquid outer core .
A magnetised excursion probably would have depart unnoticed to ancient East Africans , but today , fluctuation in the magnetic theater of operations count a draw . That ’s because the magnetic field protects the planet from the solar lead , a rate of flow of file particles from the sun . A watery field means more disruption to communications and electronic equipment from these particles .
The diachronic data will serve researchers portend what the magnetic field will do . “They’re go to be very felicitous , " Di Chiara tell .
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