Stanford scientists reveal that the winding rivers existed long before the plants stabilize their banks, which questions a central story in geology.
A team of researchers from Stanford disputes a long -standing idea that the emergence of terrestrial plants about 500 million years ago has radically changed the way in which Rivers looks and behaved.
The rivers are generally divided into two main categories: braided rivers, where several shallow channels are woven around sandy bars and winding rivers, where a single channel sculpts curves through the landscape. For decades, geologists believed that before the plants did not go, the rivers were mainly braided, and that sinuous patterns appeared only once the banks anchored of the vegetation and the sediments trapped.
The new conclusions, published in the journal Scienceargue that this point of view is ill -reading the geological file. The study shows that even vegetation -free rivers can snap, leaving deposits that closely resemble those created by braided rivers. This distinction is important because the style of a river influences the duration of sediment, carbon and nutrients in the floodplaces, shaping both ecosystems and the climate on the history of the earth.
“With our study, we reject the widely accepted history of what the landscapes looked like when plant life has evolved for the first time on earth,” said the main author Michael Hasson, doctoral student in the laboratory of Mathieu Lapôtre at the Stanford Doerr School of Sustainability. “We rewrite the history of the intertwined relationship between plants and rivers, which is an important revision of our understanding of the history of the earth.”
The floodplane plains of winding rivers – dynamic ecosystems created over thousands of years by overflowing the river – are among the most abundant non -marine carbon tanks on the planet. Carbon levels in the atmosphere, in the form of carbon dioxide, act like terrestrial thermostat, regulating temperature on large time ladders. Budgeting with precision for carbon covers created by winding rivers could help scientists build more complete models of ancient and future climate of the earth.
“The floodplates play an important role in determining how, when and if the carbon is buried or released in the atmosphere,” said Hasson. “Based on this work, we argue that carbon storage in the floodplates would have been current for much longer than the classic paradigm which assumes that winding rivers have only occurred during the last hundred years.”
Where the river flows
To assess the impact of vegetation on river channel models, researchers have examined satellite imagery of around 4,500 elbows in 49 current wind rivers. About half of the rivers were devastated and half were densely or partly green.
The researchers have registered on the occasional bars – the forms of sand that develop on the interior elbows of the winding rivers while the water flow deposits the sediments. Unlike the sand bars which are formed in the middle of the braided rivers, the bars tend to migrate laterally far from the centers of the rivers. Over time, this migration contributes to forms of characteristicly winding channel of the rivers.
Recognizing that these sand bars are formed in different places based on the style of the river, the geologists for decades have measured the trajectory of bars in the rock disc to reveal the ancient river paths. The rocks, generally sandstones and mudstones, provide proof of divergent river styles because each deposits different types and quantities of sediments forming rocks, giving geologists indices to rebuild the geometries of the river for a long time. If the sandstones showed little variation in the angle of migration of the bars, the geologists interpreted the bars as moving downstream, and therefore that a braided river created the deposits.
Using this technique, geologists had noticed that the rivers changed their way of behaving when plants have evolved for the first time on Earth. This observation led to the conclusion that land plants made the river possible, for example by trapping the sediments and stabilizing the banks.
“In our article, we show that this conclusion – which is taught in all geology programs to date – is probably incorrect,” said Lapôtre, principal author of the newspaper and assistant professor of land and planetary sciences at the Doerr School of Sustainability.
Looking at modern rivers with a wide range of plant covers, researchers have shown that plants are constantly changing the direction of migration of the punctual bar. More specifically, in the absence of vegetation, the occasional bars tend to migrate downstream – as do the intermediate bars in the braided rivers.
“In other words, we show that, if we used the same criteria as geologists used in ancient rocks on modern rivers, winding rivers would be poorly categorized as braided rivers,” said Lapostre.
Rivers over time
The results offer a new provocative window on the past Earths, upsetting the conventional image of the way in which rivers have sculpted the continents. If indeed, the floodplaces loaded with carbon were much more extensive on history, scientists may need to revise major natural climatic swings over time, with implications for our understanding of continuous climate change.
“Understand how our planet will react to the dependencies of climate change induced by man on the precise reference on the way in which he responded to past disturbances,” said Hasson. “The rock record provides this base base, but it is only useful if we interpret it with precision.”
“We suggest that an important control over the carbon cycle – where carbon is stored, and for how long, due to the type of river and the creation of floods – has not been fully understood,” he said. “Our study now shows the way for better assessments.”
Reference: “The vegetation changes the trajectory of river turns” by Michael Hasson, Alvise Fin: Alessandro Ielpi and Mathieu Ga Lapôtre, August 21, 2025, Science.
Doi: 10.1126 / Science.ADV4939
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