Sediment and rock strength controls on river incision into bedrock

Abstract

Research Article| December 01, 2001 Sediment and rock strength controls on river incision into bedrock Leonard S. Sklar; Leonard S. Sklar 1Department of Earth and Planetary Science, University of California, 307 McCone Hall, Berkeley, California 94720-4767, USA Search for other works by this author on: GSW Google Scholar William E. Dietrich William E. Dietrich 1Department of Earth and Planetary Science, University of California, 307 McCone Hall, Berkeley, California 94720-4767, USA Search for other works by this author on: GSW Google Scholar Geology (2001) 29 (12): 1087–1090. https://doi.org/10.1130/0091-7613(2001)029<1087:SARSCO>2.0.CO;2 Article history received: 05 Apr 2001 rev-recd: 11 Jul 2001 accepted: 27 Jul 2001 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Leonard S. Sklar, William E. Dietrich; Sediment and rock strength controls on river incision into bedrock. Geology 2001;; 29 (12): 1087–1090. doi: https://doi.org/10.1130/0091-7613(2001)029<1087:SARSCO>2.0.CO;2 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 Recent theoretical investigations suggest that the rate of river incision into bedrock depends nonlinearly on sediment supply, challenging the common assumption that incision rate is simply proportional to stream power. Our measurements from laboratory abrasion mills support the hypothesis that sediment promotes erosion at low supply rates by providing tools for abrasion, but inhibits erosion at high supply rates by burying underlying bedrock beneath transient deposits. Maximum erosion rates occur at a critical level of coarse-grained sediment supply where the bedrock is only partially exposed. Fine-grained sediments provide poor abrasive tools for lowering bedrock river beds because they tend to travel in suspension. Experiments also reveal that rock resistance to fluvial erosion scales with the square of rock tensile strength. Our results suggest that spatial and temporal variations in the extent of bedrock exposure provide incising rivers with a previously unrecognized degree of freedom in adjusting to changes in rock uplift rate and climate. Furthermore, we conclude that the grain size distribution of sediment supplied by hillslopes to the channel network is a fundamental control on bedrock channel gradients and topographic relief. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.