Rethinking River Dynamics Before the Advent of Plants

Geologists have long believed that rivers before the emergence of plants followed meandering patterns and that braided rivers only formed after plants took root and stabilized riverbanks. However, a new study published in the journal Science on August 21, 2025, suggests that this theory may be based on a misinterpretation of the geological record.

The Geological Significance of Rivers

Rivers are among the most prominent geological features that shape the Earth’s surface. They generally fall into two main patterns: braided rivers, where multiple channels flow around sandy bars, and meandering rivers, which form S-shaped curves across landscapes. Geologists have long thought that ancient rivers followed a braided pattern before the appearance of plants.

However, the new study indicates that non-vegetated meandering rivers can leave sedimentary deposits that deceptively resemble those of braided rivers. This discovery is significant for our understanding of the Earth’s ancient environment and climate.

The Relationship Between Rivers and Plants

Meandering rivers are among the most dynamic ecosystems, contributing to the formation of silt over thousands of years. These systems play a crucial role in carbon storage, one of the most important processes affecting the Earth’s climate. Atmospheric carbon, in the form of carbon dioxide, acts as a regulator of the Earth’s temperature over long periods.

The researchers explained that meandering rivers can store carbon in floodplains for longer periods than previously thought. This challenges the traditional understanding that meandering rivers only existed in the last hundreds of millions of years.

The Impact of Vegetation on River Patterns

Researchers examined satellite images of approximately 4,500 bends in 49 currently meandering rivers. Half of these rivers were non-vegetated, while the other half were partially or densely vegetated. The researchers focused on the sandy lands that form on the inner bends of meandering rivers due to sediment deposition.

Scientists observed that the locations where these sandy lands form depend on the river pattern, which can alter the traditional understanding of river history. In the absence of vegetation, sandy lands tend to migrate toward the current, making them appear similar to braided rivers.

Reevaluating the Geological Record

The recent discoveries provide a new perspective on Earth’s past, challenging the conventional idea of how rivers shaped continents. If carbon-rich floodplains formed more extensively in history, scientists may need to revise models related to major natural climate changes over time.

Researchers emphasize the importance of the geological record in providing an accurate database for understanding how our planet responds to human-induced climate changes. However, this record will only be useful if interpreted correctly.

Conclusion

The study suggests that our understanding of the role of rivers in carbon storage may be incomplete, necessitating a reevaluation of how rivers impact climate and Earth’s history. Recent research shows that non-vegetated meandering rivers can store carbon for long periods, altering the traditional understanding of the relationship between rivers, plants, and their environmental impact.