How did Mount Everest become the highest peak? In 2006, scientists found a big clue to how some of Earth's tallest mountains formed

For generations, scientists believed the towering Andes Mountains rose slowly over tens of millions of years as Earth's tectonic plates pushed together and folded the crust. A new study published in the journal Science challenges that long-held idea, suggesting large sections of the Andes reached their remarkable heights in as little as 7 million years. The discovery is prompting geologists to rethink one of the most fundamental theories about how mountain ranges form.

The research points to an unexpected force deep beneath Earth's surface. Instead of surface crust alone driving the uplift, scientists believe giant masses of buoyant material inside the planet may have helped push parts of the Andes upward far more rapidly than previously thought. The findings add to growing evidence that Earth's interior plays a much larger role in shaping the planet's landscape than earlier models suggested.

A new timeline for the rise of the Andes

The Andes stretch for nearly 5,500 miles (8,900 kilometers) along the western edge of South America, making them the longest continental mountain range on Earth. They formed as the Nazca Plate continues to slide beneath the South American Plate, a process known as subduction.


Traditional geological models proposed that mountain building occurred gradually as the Earth's crust thickened through folding and faulting over tens of millions of years. The new study paints a different picture. Researchers found evidence indicating that significant portions of the central Andes gained most of their elevation within approximately 7 million years, an exceptionally short period on the geological timescale.

If additional studies confirm these findings, scientists may need to revise long-standing models used to explain not only the Andes but also mountain-building processes worldwide.

Deep mantle material may have accelerated mountain growth

The research suggests that the rapid uplift cannot be explained by crustal compression alone. Instead, scientists propose that a large body of unusually hot or buoyant material located deep within Earth's mantle contributed to lifting the overlying crust.

Rather than acting like a simple collision between tectonic plates, the Earth's interior may have supplied additional upward force from below. This deeper geological process could explain why some mountain ranges experience periods of rapid elevation while others develop much more slowly.

Scientists often compare Earth's mantle to a very slowly flowing solid. Although rocks in the mantle remain solid under enormous pressure, they can gradually move over millions of years. These movements influence plate tectonics, volcanic activity, earthquakes, and, according to the new research, possibly the speed at which mountains rise.

The study does not claim that mantle processes replace plate tectonics. Instead, it suggests both mechanisms likely worked together to create the Andes' dramatic elevation.

Ancient plant fossils revealed hidden geological history

Determining how high ancient mountains once stood is one of geology's greatest challenges because erosion constantly reshapes landscapes. Over millions of years, wind, rain, rivers, glaciers, and weathering remove large amounts of rock, erasing direct evidence of earlier elevations.

To reconstruct the Andes' ancient height, researchers analyzed fossilized soils that preserved traces of ancient plant life. Different plant species thrive within specific temperature ranges that often correspond to particular elevations.

By comparing fossil evidence with modern ecological relationships and geological data, scientists estimated how high sections of the Andes were millions of years ago. The results suggested a much faster rise than previously believed.

Researchers acknowledge that fossil-based elevation estimates are not perfect. Climate conditions change through time, and plants can adapt to new environments. For that reason, the study combines fossil evidence with additional geological measurements to strengthen its conclusions rather than relying on a single method.

The discovery challenges long-standing geological models

For decades, geology textbooks described mountain building primarily as the result of crustal shortening. According to that model, tectonic plates collide, rocks fold and fracture, the crust thickens, and mountains slowly rise over millions of years.

The new findings suggest that explanation may be incomplete. The researchers argue that deep-Earth dynamics may provide an additional mechanism capable of producing rapid uplift. If buoyant mantle material rises beneath continental crust, it can increase elevation without requiring enormous amounts of crustal thickening alone.

This emerging idea aligns with several recent geological studies indicating that mountain belts may grow in pulses rather than through slow, continuous uplift.

Scientists emphasize that further research is necessary before applying the model universally. Mountain ranges such as the Himalayas, Alps, Rockies, and others formed under different tectonic conditions, and researchers will continue investigating whether similar deep-mantle processes influenced their development.

Even so, the study represents one of the strongest pieces of evidence yet that Earth's interior may play a far greater role in mountain formation than previously recognized.

Why the findings matter beyond the Andes

Although the research focuses on South America, its implications extend far beyond one mountain range. Understanding how mountains form helps scientists improve models of plate tectonics, earthquakes, volcanic systems, landscape evolution, and long-term climate change.

Mountain ranges influence rainfall patterns, river systems, biodiversity, and atmospheric circulation. Better knowledge of how they form allows researchers to reconstruct Earth's environmental history with greater accuracy.

The findings also demonstrate how advances in geological science continue to reshape our understanding of the planet. Improved dating techniques, isotope analysis, fossil studies, and computer modeling now allow scientists to test ideas that were impossible to evaluate just a few decades ago.

Rather than overturning plate tectonics, the study expands scientists' understanding of the complex interactions occurring between Earth's crust and its deep interior. As more evidence emerges from mountain systems around the world, researchers will determine whether rapid uplift driven by mantle processes is a common feature of Earth's evolution or a unique characteristic of the Andes.

Published in Science, the research marks another important step toward understanding the powerful forces that continue to shape Earth's surface. It also highlights that even familiar landscapes can still hold geological surprises waiting to be uncovered through new technology and fresh scientific investigation.