A team of scientists from the University of Rochester in the US have resorted to quite an unusual source of information to estimate fluctuations of magnetic field of the Earth.The South Atlantic Anomaly is a geomagnetic anomaly that stretches from South America to southern parts of Africa. This is where Earth’s magnetic field is the weakest, and, at sea level, equals 1,000 km above sea level in other parts of the world. If one puts a compass deep beneath South Africa, they will find that down there, despite being located in Southern Hemisphere, the compass will actually point north.For the last 160 years, the strength of Earth’s magnetic field has been decreasing at what the scientists call an “alarming rate,” making scientists talk of an impending magnetic pole switch that could happen, but nobody actually knows when. However, such an occurrence would definitely lead to massive electric system disruptions, so it’s better to be prepared.
At present, it is impossible to jump to any conclusion or prediction without knowing the bigger picture: the last time the poles switched, the scientists say was 800,000 years ago. In other words, 160 years is just too small a time span to tell anything.In order to take a deeper look, the team of Rochester scientists, led by John Tarduno, a professor and chair of the Department of Earth and Environmental Sciences, turned towards an unusual source of information they found in South Africa.It turns out, that during the Iron Age, Bantu-speaking tribes expanded in South Africa, and those tribes had an interesting custom: during the arid years, they burned some of their houses as a sacrifice, and those houses were made of clay. The clay includes magnetic particles, which change their positioning according to the Earth’s magnetic field. And when the house burns, the high temperature effectively cements those magnetic minerals in one position, EurekAlert reports.