The fracture of the African continent begins to become visible in the Great Rift Valley, in Sheno, Ethiopia
The division of the African continent is at a more advanced stage of its separation process than previously thought. According to a new study, the Turkana Rift Zone is active, and has passed a critical geological threshold, which makes continental breakup virtually inevitable.
Geologists have known for some time that the African tectonic plate is divide into two: the large Nubian plate, to the west, which covers most of the continent, and the smaller Somali plate, to the east, which includes much of the eastern coast and Madagascar.
This fracture of the African continental plate, according to scientists, will give rise to . But we won’t be here to see it.
In 2009, researchers at the University of Rochester in the United Kingdom revealed for the first time that geological changes in the Afar regionin Ethiopia, were causing the division of the continent.
According to , then published in Geophysical Research LettersSomalia, half of Ethiopia, Kenya, Tanzania and part of Mozambique will separate to form a new continent, a process that will take place from now on five million years, a relatively short time on a geological scale.
Latest GPS data, presented in a 2021 published in the journal Geology by researchers from Virginia Tech, in the USA, allowed us to conclude that the division of the African tectonic plate is still more extensive than imagined.
But according to a new report, published last week in the magazine Nature Communicationsthe process of division of the African continent is at a more advanced stage than was thought.
The study, conducted by a team of researchers led by geoscientist Christian Rowanfrom Columbia University in the US, analyzed seismic data from the Turkana Rift Zone, a vast geological formation that stretches hundreds of kilometers across Kenya and Ethiopia.
The study authors found that the earth’s crust in the Turkana Rift area is much thinner than we thought we knew: the center of the rift has just 13 kmcompared to more than 35 km within its limits.
This thinning is significant. When the crust in a rift zone drops below a critical limit of about 15 kmenters a phase that geologists call necking — a point of no return from which continental fragmentation becomes practically certain.
“The thinner the crust becomes, the more fragile it becomeswhich contributes to the continuation of the rifting process”, explained Rowan to .
Within a few million years, the rift will advance to its next phase, known as oceanization: the crust will stretch until magma erupts from the depths, eventually forming a new ocean flooras the waters of the Indian Ocean invade the region. This process is already visibly underway in the Afar Depression, next to the Red Sea.
In addition to its geological relevance, the discovery has profound implications for understanding human origins. The Turkana Rift Zone is one of the richest Worldwide sources of early hominid fossilslong considered a cradle of human evolution.
However, the region’s extraordinary fossil record could owe more to geology than biology: the team estimates that the rift entered its necking phase about four million yearsa chronology that remarkably coincides with the age of the oldest hominin fossils found in the area.
But this will not be a coincidence, the study authors suggest: as tectonic activity intensified, sediments accumulated fastercreating ideal conditions for the preservation of remains.
Thus, contrary to what was believed, the region may not have been particularly important for the first humans; could simply have been exceptionally conducive to preserving evidence of its existence.
