Morphometric dating of the fluvial landscape response to a tectonic perturbation

Abstract

Despite constant progress in numerical and field studies of landscape evolution, time evolution is still poorly constrained in many uplifted areas where low denudation rates prevent the use of low temperature thermochronology, especially outside high relief mountainous areas. Here, I show that regional statistics of the landscape metric R involving hypsometric integrals at three nested levels of a catchment are able to isolate the time effect on landscape geometry during the latter's transient response to a tectonic perturbation. Analysis of 210 catchments from 9 regions of known uplift age worldwide shows that the regionally characteristic, R-derived S R index is in inverse power law relation with the time elapsed since a base level lowering. Suggesting a response time of ∼5 My, this finding has important implications for quantifying the rate of landform evolution and determining whether a landscape has reached steady-state form. © 2012. American Geophysical Union. All Rights Reserved.