Canyons with undulating walls

Abstract

Research Article| July 01, 1999 Canyons with undulating walls Ellen E. Wohl; Ellen E. Wohl 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Search for other works by this author on: GSW Google Scholar Douglas M. Thompson; Douglas M. Thompson 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Search for other works by this author on: GSW Google Scholar Andrew J. Miller Andrew J. Miller 2Department of Geography, 1000 Hilltop Circle, University of Maryland at Baltimore County, Baltimore, Maryland 21250 Search for other works by this author on: GSW Google Scholar Author and Article Information Ellen E. Wohl 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Douglas M. Thompson 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Andrew J. Miller 2Department of Geography, 1000 Hilltop Circle, University of Maryland at Baltimore County, Baltimore, Maryland 21250 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1999) 111 (7): 949–959. https://doi.org/10.1130/0016-7606(1999)111<0949:CWUW>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Ellen E. Wohl, Douglas M. Thompson, Andrew J. Miller; Canyons with undulating walls. GSA Bulletin 1999;; 111 (7): 949–959. doi: https://doi.org/10.1130/0016-7606(1999)111<0949:CWUW>2.3.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 SocietyGSA Bulletin Search Advanced Search Abstract Channels incised into cohesive substrates commonly develop undulating walls characterized by regular, repetitive variations in channel width. Canyons with undulating walls are found in a variety of lithologic, climatic, and tectonic regimes, and are most commonly present downstream from a knick zone of active incision. Flume experiments and natural channel morphologic patterns lead us to infer that wall undulations are the remnants of breached, offset potholes or of sinuous longitudinal grooves formed during incision of the knick zone. Substrate characteristics seem to have little influence on these undulations. Using measurements from eight channels incised into the Navajo Sandstone of southern Utah, we found that intact rock strength, rock-mass strength, joint orientation and spacing, bedding, and porosity did not differ significantly between channel reaches with straight walls, undulating walls, and meanders. The wavelength and amplitude of wall undulations also did not correlate with any substrate characteristic. These results lead us to conclude that the primary control on formation of undulating walls is hydraulic processes.Along the study channels, deep, narrow reaches with undulating walls alternate with wider straight or meandering reaches. Using flume simulations and one- and two-dimensional hydraulic modeling, we found that the wall undulations act to reduce interreach (spatial) variability in energy expenditure, and to minimize energy expenditure within a reach. We propose that the wall undulations and flow hydraulics create a feedback whereby the wall undulations are preserved following knickpoint incision. The wall undulations then act to regulate downstream energy expenditure in a manner analogous to bedforms. This implies that generalized principles of uniform energy expenditure developed for alluvial channels may also apply at the reach scale to bedrock channels with relatively homogeneous substrates. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.