Beyond threshold hillslopes: Channel adjustment to base-level fall in tectonically active mountain ranges

Abstract

Research Article| July 01, 2009 Beyond threshold hillslopes: Channel adjustment to base-level fall in tectonically active mountain ranges William B. Ouimet; William B. Ouimet 1Department of Geology, Colorado College, Colorado Springs, Colorado 80903, USA Search for other works by this author on: GSW Google Scholar Kelin X Whipple; Kelin X Whipple 2School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA Search for other works by this author on: GSW Google Scholar Darryl E. Granger Darryl E. Granger 3Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907, USA Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (7): 579–582. https://doi.org/10.1130/G30013A.1 Article history received: 08 Jan 2009 rev-recd: 08 Jan 2009 accepted: 28 Jan 2009 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation William B. Ouimet, Kelin X Whipple, Darryl E. Granger; Beyond threshold hillslopes: Channel adjustment to base-level fall in tectonically active mountain ranges. Geology 2009;; 37 (7): 579–582. doi: https://doi.org/10.1130/G30013A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Numerous empirical and model-based studies argue that, in general, hillslopes and river channels increase their gradients to accommodate high rates of base-level fall. To date, however, few data sets show the dynamic range of both these relationships needed to test theoretical models of hillslope evolution and river incision. Here, we utilize concentrations of 10Be in quartz extracted from river sand on the eastern margin of the Tibetan Plateau to explore relationships among short-term (102–105 a) erosion rate, hillslope gradient, and channel steepness. Our data illustrate nonlinear behavior and a threshold in the relationship between erosion rate and mean hillslope gradient, confirming the generalization that hillslopes around the world are limited by slope stability and cease to provide a metric for erosion at high rates (>~0.2 mm/a). The relationship between channel steepness index and erosion rate is also nonlinear, but channels continue to steepen beyond the point where threshold hillslopes emerge up to at least 0.6 mm/a, demonstrating that channel steepness is a more reliable topographic metric than mean hillslope gradient for erosion rate and that channels ultimately drive landscape adjustment to increasing rates of base-level fall in tectonically active settings. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.