River erosion drives uneven uplift in Basque‑Cantabrian range, researchers report

A research team from the University of the Basque Country (EHU) has linked the contrasting heights of crustal rise on the Atlantic and Mediterranean flanks of the Basque‑Cantabrian Range to differences in river erosion, the study shows.

Measurements indicate that the Atlantic‑facing slope has been lifted by roughly 255 metres (837 feet), while the opposite Mediterranean side has risen about 167 metres (548 feet). The disparity, the scientists argue, is not a product of tectonic forces alone but reflects how rivers have sculpted the landscape over millions of years.

Using high‑resolution digital elevation models and analyses of river longitudinal profiles, the EHU group mapped the incision depth of major waterways on both sides of the range. By correlating the depth of valleys with uplift estimates derived from thermochronology and GPS data, they demonstrated that more vigorous fluvial erosion on the Atlantic side has removed greater amounts of material, prompting a larger isostatic response from the underlying crust.

In simple terms, when a river cuts deeply into a mountain, the reduction in overlying weight allows the mantle beneath to rise, a process known as isostatic rebound. Because the Atlantic‑draining rivers have a steeper gradient and higher discharge, they have eroded their valleys more aggressively than the Mediterranean‑draining systems, leading to the observed uplift imbalance.

The findings add nuance to the geological picture of the region, which sits at the boundary between the Eurasian and Iberian plates. While the area has long been considered relatively stable compared with the more active Alpine front, the new evidence underscores that surface processes such as erosion can significantly modulate crustal movements even in ostensibly passive settings.

Understanding the interplay between river erosion and uplift has practical implications for seismic risk assessment, groundwater management, and long‑term landscape evolution. The researchers suggest that continued monitoring of river incision rates, combined with satellite‑based deformation measurements, will help refine models of how the Basque‑Cantabrian Range will respond to both natural and anthropogenic changes in the coming decades.