Australia: The Land Where Time Began

A biography of the Australian continent 

Bedrock Canyon – Amplification by Wind Incision

On both Earth and Mars bedrock canyons are ubiquitous, and the morphology of river canyons is often used to interpret the climatic and tectonic histories of the landscape (Ferrier, Huppert & Perron, 2013; Howard, Dietrich & Seidl, 1994; 1994; Schoenbohm et al., 2004). However, on both planets there are many bedrock canyons in dry environments that are dominated by wind (Goudie & Mega-Yardangs, 2007; Baker, 2001; Howard, Moore & Irwin, 2005). The role of wind in shaping bedrock canyon systems in arid environments is poorly understood and is therefore typically neglected, though wind abrasion can significantly influence the evolution of arid landscapes (Goudie & Mega-Yardangs, 2007; McCauley, 1973). In this paper Perkins, Finnegan & de Silva exploit a section on the western slope of the Andes that allows direct comparison of canyons that are wind-affected and wind-protected as a natural experiment. They have shown that the amplification of bedrock canyon incision rates by wind can be an order of magnitude above fluvial rates, by the use of a combined analysis of the morphology of 36 canyons and topographic wind simulations. Wind is implied by their results to be capable of extending bedrock canons, landforms that have traditionally been believed to evolve by water flowing through the canyons. Their analyses also reveal a direct relationship between aerodynamics and the evolution of landscape on varying scales. Topographic shielding by high mountains of high winds modulates the rapidity with which canyons retreat. Their conclusion is that wind abrasion can modify significantly the bedrock canyon morphology and suggest that fluvial landscapes may have been similarly reshaped on the surface of mars.

Sources & Further reading

1. Perkins, J. P., N. J. Finnegan and S. L. de Silva (2015). "Amplification of bedrock canyon incision by wind." Nature Geosci 8(4): 305-310.