Pedro Val, Jane K. Willenbring

The spine of Andes – the trace of the highest mountain topography – weaves back and forth, in places near the coastline, in others farther inland. Its position is thought to be partially influenced by the asymmetric distribution of rainfall causing the migration of the topographic divide (i.e. mountain peaks) in favor of the more erosive (wetter) side and consuming the less erosive (drier) side. Here, we demonstrate that erosion rates in the Andes are not controlled by rainfall and conclude that the position of this mountain chain is better described by the age and radius of curvature of the subducting Nazca plate. Our results suggest that mountain range migration might be a common component of orogenesis but for reasons different than those predicted by coupled climate-tectonic models. Cyclical variations in Andean orogeny might also accompany lateral migrations of mountain ranges.