This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A University of the Basque Country-EHU research group has determined the causes of a 255 m (837 feet) crustal uplift of the Atlantic slope and a 167 m (548 feet) uplift of the Mediterranean slope, as well as the development of rivers in these areas. Researchers from the Department of Geography, Prehistory and Archaeology and the Department of Geology at EHU and the Department of Geology at USAL have quantified for the first time the difference in relief between the two slopes of the mountain range extending from Castro Valnera (on the border between Burgos and Cantabria) to the Pyrenees.
The study is published in the journal Geomorphology. Since the formation of the range, differential erosion of the slopes has caused the crust of the Atlantic slope to rise more than that of the Mediterranean slope. Similar to boats that float higher in the water when weight is unloaded, Earth's crust rises as it loses the weight of surface rocks.
The collision of tectonic plates results in the formation of mountain ranges, but their relief continues to rise afterward. In fact, tectonic plates float over Earth's mantle on the asthenosphere (a layer that extends from the base of the crust at a depth of 100 km [62 miles] to 660 km [410 miles]). According to Iván Martín Martín, a researcher in the Department of Geography, Prehistory and Archaeology at the University of the Basque Country-EHU, "when the load on the tectonic plates lessens, the relief gradually rises, in a similar way to boats, to maintain a certain stability." This is known as isostatic adjustment, and it is particularly pronounced in areas where glaciers are disappearing, for example.
Understanding isostatic adjustment is fundamental to understanding changes in sea level and the evolution of Earth's landscape. The Basque–Cantabrian Range separates the two watersheds in the north of the Iberian Peninsula; one drains into the Cantabrian Sea and the other into the Mediterranean Sea. Therefore, this mountain range forms a dividing line between two distinct slopes: the Atlantic and Mediterranean.
The EHU research group's aim is to explain the contrast between the two slopes. Martín has estimated that, from the formation of the Basque–Cantabrian Range to the present day, 2,019 km3 of rock has been eroded on the Atlantic slope and 1,408 km3 on the Mediterranean slope. According to the EHU researcher, "differential erosion has taken place; the Atlantic slope has suffered more erosion, which has caused a greater isostatic uplift.
The relief of the Atlantic slope has risen by approximately 255 m, while the relief of the Mediterranean slope has risen by 167 m, representing a difference of 88 m between the two slopes." He added, "Although erosion is considerable, it will continue in the future; that is, more surface rocks will erode and, as a result, the relief will continue to rise." The rivers of 35 basins on both slopes were analyzed (13,190 km2) using conventional and modern methods. "To date, not many studies have been conducted globally on this topic. They have mainly been carried out in glacial areas.
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