New research shows meandering rivers existed long before vegetation, reshaping our understanding of Earth’s climate history

Challenging a Classic Geological Paradigm

A new study from Stanford University overturns a decades-old view that the rise of land plants roughly 500 million years ago fundamentally changed the way rivers flowed.

Traditionally, geologists believed that before vegetation stabilized riverbanks, rivers ran almost exclusively in braided patterns—with multiple channels winding around sandy bars. After plants appeared, rivers were thought to evolve into meandering styles, where single channels form sweeping S-curves across landscapes.

The new findings, to be published Aug. 21, 2025, in Science, reveal that unvegetated meandering rivers can leave behind rock records that mimic braided rivers. This misinterpretation has fueled a long-standing misconception about the link between vegetation and river morphology.

“With our study, we’re pushing back on the widely accepted story of what landscapes looked like when plant life first evolved on land,” said lead author Michael Hasson, a PhD student in the lab of Mathieu Lapôtre at the Stanford Doerr School of Sustainability. “We’re rewriting the story of the intertwined relationship between plants and rivers, which is a significant revision to our understanding of the history of the Earth.”

Rivers, Floodplains, and Carbon Storage

Meandering rivers are crucial for climate regulation because they form floodplains—muddy, carbon-rich ecosystems that trap sediment and nutrients for thousands of years. These floodplains are among the planet’s largest non-marine carbon stores, playing a key role in Earth’s long-term carbon cycle.

“Floodplains play an important role in determining how, when, and whether carbon is buried or released back into the atmosphere,” Hasson said. “Based on this work, we argue carbon storage in floodplains would have been common for much longer than the classic paradigm that assumes meandering rivers only occurred over the last several hundred million years.”

Rethinking the Evidence

To evaluate the role of vegetation, researchers analyzed satellite imagery of about 4,500 bends across 49 meandering rivers worldwide, some densely vegetated and others largely barren.

They focused on point bars—sandy deposits that form on the inner bends of meandering rivers. In vegetated rivers, point bars migrate laterally, shaping the river’s curves. Without vegetation, however, the team showed point bars tend to move downstream, making their rock deposits resemble those of braided rivers.

“In our paper, we show that this conclusion – which is taught in all geology curricula to this day – is most likely incorrect,” said Mathieu Lapôtre, senior author and assistant professor of Earth and planetary sciences.

“In other words, we show that, if one were to use the same criterion geologists use in ancient rocks on modern rivers, meandering rivers would be miscategorized as braided rivers,” he added.

Implications for Earth’s Climate History

The findings suggest that meandering rivers, and their associated carbon-rich floodplains, existed long before the rise of plants—meaning carbon storage has shaped Earth’s climate for far longer than previously assumed.

“Understanding how our planet is going to respond to human-induced climate change hinges on having an accurate baseline for how it has responded to past perturbations,” Hasson said. “The rock record provides that baseline, but it’s only useful if we interpret it accurately.”

The research team included collaborators from the University of Padova and the University of British Columbia.

Summary

• A Stanford study challenges the belief that plants made meandering rivers possible.
• Unvegetated meandering rivers can mimic braided rivers in the rock record, leading to misinterpretation.
• Findings suggest floodplain carbon storage has been a key climate regulator far longer than assumed.
• Results may prompt revisions to models of Earth’s climate history and its response to future change.

Original Publication
Authors: Michael Hasson, Alvise Finotello, Alessandro Ielpi and Mathieu G. A. Lapôtre.
Journal: Science
DOI: 10.1126/science.adv4939
Article Title: Vegetation changes the trajectory of river bends
Article Publication Date: 21-Aug-2025