An ancient practice of ritualistic cleansing in South African agricultural communities has led researchers to record a magnetic field history of the region that is believed to play a major role in the reversal of Earth’s magnetic poles. The study, which was the first of its kind, was published in the journal Nature Communications.
Study is First to Record Magnetic Field History in South Africa
Three universities teamed up to acquire the first record of magnetic fields in South Africa using minerals from the Iron Age and archaeological data from ritualistic burning ceremonies in agricultural settlements.
Research findings revealed that with the archaeological evidence and the current weakening of the magnetic fields, South Africa’s core region may be the genesis of the most recent (as in 800,000 years ago recent) and even future pole reversals, which take nearly 15,000 years to complete once started.
The study was led by John Tarduno, geophysicist from the University of Rochester, and carried out by researchers from South Africa’s University of the Witwatersrand and University of KwaZulu-Natal.
Their data is groundbreaking in the field of earth sciences and geophysics because it suggests that pole reversals don’t begin in random locations as previously thought.
How Archaeology and Minerals Revealed the Importance of the Magnetic Fields
Tarduno and his research team wanted to collect concrete evidence to accurately record South Africa’s magnetic fields from the Iron Age rather than use estimates from models using approximate data collected around the world. They turned to archaeologists for extra help.
These experts on ancient African rituals and practices explained the early practices of cleansing villages through burning huts and grain bins. While it seems like a rather unimportant event for geophysicists, this practice of igniting the village would have created a fire that reached over 1000 degrees Celsius as it consumed the clay floors of the structures.
This fire would be so scorching hot it would burn through, erasing the old information stored in the magnetite while creating a new record of magnetic information, like field strength and direction.
So, in other words, they would be able to actually see when the magnetic intensity in the area had increased or decreased thanks to the practices of these ancient Africans.
That’s exactly what happened too! Tarduno’s team found a 30% decrease in magnetic field intensity in the Iron Age (1225 to 1550 AD). This parallels what is happening today in the region, leading the researchers to the conclusion that this gradual weakening may reappear every few (thousand) years.
Earth Sciences, Geophysics, and Even More Technical Understanding of the Magnetic Fields
The research data was collected from sites along Zimbabwe and Botswana, focusing near the Limpopo River. The sites were all within a region with an extremely weak magnetic field strength called the South Atlantic Anomaly (SAA).
Other research has shown Earth’s magnetic field in the North and South Poles has decreased 16% of the past nearly 200 years with most of the weakening has occurred in the SAA. Some scientists believe this is the first sign of the Earth going into a pole reversal. However, the research team has said that weakening fields may recover without the poles reversing. It happens all the time!
Meanwhile, their study has proven, for the first time, that the low magnetic field strength in the Southern Hemisphere’s SAA is a result of geology. This region features a core that is overlain with hot, dense mantle rock that is 3000 km below the surface and 6,000 km across the region.
So How Does South Africa Fit Into This?
The researchers hypothesized that the specific region in South Africa actually affects Earth’s magnetic field as the liquid iron within the Earth shifts its flow near the region thanks to the special feature of the hot, dense mantle rock. This shift causes irregularities in the field, which results in lesser magnetic intensities.
The area, which is called a Large Low Shear Velocity Province (LLSVP), is theorized to perhaps be the trigger for magnetic pole reversals as the weak magnetic field gets larger.
However, the research team pointed out that though the new data is interesting, it cannot predict or conclusively say that we are in a reversal or will soon be in one. Instead, it simply suggests that the latest research on magnetic fields in South Africa shows a possible pattern in Earth’s pole reversals, which in itself is pretty impressive.
