Placer mining along the Fraser River, British Columbia: The geomorphic impact

Abstract

Research Article| July 01, 2012 Placer mining along the Fraser River, British Columbia: The geomorphic impact Andrew D. Nelson; Andrew D. Nelson † Department of Geography, University of British Columbia, 1984 W. Mall, Vancouver, British Columbia V6T 1Z2, Canada †E-mail: andrewdnelson@gmail.com Search for other works by this author on: GSW Google Scholar Michael Church Michael Church Department of Geography, University of British Columbia, 1984 W. Mall, Vancouver, British Columbia V6T 1Z2, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Andrew D. Nelson † Department of Geography, University of British Columbia, 1984 W. Mall, Vancouver, British Columbia V6T 1Z2, Canada Michael Church Department of Geography, University of British Columbia, 1984 W. Mall, Vancouver, British Columbia V6T 1Z2, Canada †E-mail: andrewdnelson@gmail.com Publisher: Geological Society of America Received: 25 Jul 2011 Revision Received: 02 Feb 2012 Accepted: 07 Feb 2012 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2012 Geological Society of America GSA Bulletin (2012) 124 (7-8): 1212–1228. https://doi.org/10.1130/B30575.1 Article history Received: 25 Jul 2011 Revision Received: 02 Feb 2012 Accepted: 07 Feb 2012 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Andrew D. Nelson, Michael Church; Placer mining along the Fraser River, British Columbia: The geomorphic impact. GSA Bulletin 2012;; 124 (7-8): 1212–1228. doi: https://doi.org/10.1130/B30575.1 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 SocietyGSA Bulletin Search Advanced Search Abstract We investigate the geomorphic impact of nineteenth century placer mining along the Fraser River, British Columbia, by estimating the volume and grain-size distribution of excavated sediment, evaluating the transport potential for the sediment in the river, and discussing the relation between placer waste sediment and observed morphodynamics of the Fraser River channel. Volume-by-area regression relations applied to 456 mapped mines estimate the total volume of material excavated to be ∼58 × 106 m3 (bulk volume). Sampling of mine scarp and mine lag sediments indicates that the discharged tailings consisted of 54% sand and finer material and 46% gravel and small cobbles. Modern observation and historical narratives indicate that the channel of the Fraser between Quesnel and Laidlaw has been generally stable following placer mining. Application of a sediment transport function indicates that the river is capable of moving annually an amount of sediment comparable to the maximum loading from placer mining. By applying established relations between channel scale and sediment virtual velocity, we estimate the rate of downstream movement of the placer-waste slug to be between 1 and 6 km yr−1. The predicted rates of sediment migration indicate that peak delivery of placer waste to the lower river below Laidlaw likely occurred early in the twentieth century. This predicted behavior agrees well with observed aggradation on the lower river. The result emphasizes the importance of historical legacy in the appraisal of recent geomorphological processes and shows that widespread small-scale disturbance has affected the Fraser River, with the effect concentrated where the gradient of the river is reduced. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.