Scientists Uncover Mystery Behind Rising Continents

Occasionally, stable parts of Earth’s continents rise, creating striking topographic features. Scientists at the University of Southampton have uncovered why this occurs by studying plate tectonics. They found that the breakup of tectonic plates triggers powerful waves deep within the Earth, causing continental surfaces to elevate by over a kilometer.

Researchers have long sought to understand the formation of topographical features such as “escarpments” and “plateaus.” The new findings, published in the journal Nature, stem from examining the impact of global tectonic forces on landscape evolution over hundreds of millions of years.

“Scientists have long suspected that steep kilometre-high topographic features called Great Escarpments—like the classic example encircling South Africa—are formed when continents rift and eventually split apart,” said Tom Gernon, Professor of Earth Science at the University of Southampton and lead author of the study.

The study involved researchers from the University of Southampton, including Dr. Thea Hincks, Dr. Derek Keir, and Alice Cunningham, in collaboration with colleagues from the Helmholtz Centre Potsdam—GFZ German Research Centre for Geosciences and the University of Birmingham. They aimed to understand why stable continental areas sometimes experience vertical movement.

The team discovered that as continents split, their crust stretches, causing stirring movements in the Earth’s mantle. Professor Sascha Brune, leader of the Geodynamic Modelling Section at GFZ Potsdam, explained, “This process can be compared to a sweeping motion that moves towards the continents and disturbs their deep foundations.”

By running simulations, Professor Brune and Dr. Anne Glerum noted that the speed of mantle “waves” moving beneath continents closely matched the pace of major erosion events in Southern Africa following the breakup of the ancient supercontinent Gondwana. They found that Great Escarpments form at the edges of ancient rift valleys, indicating that a rifting event initiates a “deep mantle wave.” This wave travels along the continent’s base at about 15–20 kilometers per million years.

“Much like how a hot-air balloon sheds weight to rise higher, this loss of continental material causes the continents to rise—a process called isostasy,” added Professor Brune.