Amplification of bedrock canyon incision by wind


Amplification of bedrock canyon incision by wind

Jonathan P. Perkins,Noah J. Finnegan & Shanaka L. de Silva

http://www.nature.com/ngeo/journal/v8/n4/abs/ngeo2381.html


Abstract

Bedrock canyons are ubiquitous on Earth and Mars, and river canyon morphology is commonly used to interpret the climatic and tectonic histories of landscapes1, 2, 3. On both planets, however, many bedrock canyons exist in dry, wind-dominated environments4, 5, 6. Although wind abrasion can significantly influence the evolution of arid landscapes4, 7, the role of wind in shaping arid bedrock canyon systems is poorly understood and thus typically neglected. Here we exploit a natural experiment on the western slope of the central Andes that allows direct comparison of wind-affected and wind-protected canyons. Through a combined analysis of the morphology of 36 canyons and topographic wind simulations, we show that wind abrasion can amplify bedrock canyon incision rates by an order of magnitude above fluvial rates. Our results imply that wind can extend bedrock canyons—landforms traditionally thought to evolve only from flowing water. Furthermore, our analyses reveal a direct relationship between aerodynamics and landscape evolution on varying scales. Topographic shielding of high winds by mountains modulates the pace of canyon retreat, while individual canyon profiles become aerodynamically streamlined. We conclude that wind abrasion can significantly modify the morphology of bedrock canyons and suggest that wind may have similarly reshaped fluvial landscapes on the martian surface.