Geologic Framework of Large Historic Landslides in Thompson River Valley, British Columbia

Abstract

Research Article| March 01, 2003 Geologic Framework of Large Historic Landslides in Thompson River Valley, British Columbia JOHN J. CLAGUE; JOHN J. CLAGUE 1Department of Earth Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6 Canada; and Geological Survey of Canada, 101-605 Robson St., Vancouver, BC, V6B 5J3 Canada; email: jclague@sfu.ca Search for other works by this author on: GSW Google Scholar STEPHEN G. EVANS STEPHEN G. EVANS 2Geological Survey of Canada, 601 Booth St., Ottawa, ON, K1A 0E8 Canada Search for other works by this author on: GSW Google Scholar Author and Article Information JOHN J. CLAGUE 1Department of Earth Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6 Canada; and Geological Survey of Canada, 101-605 Robson St., Vancouver, BC, V6B 5J3 Canada; email: jclague@sfu.ca STEPHEN G. EVANS 2Geological Survey of Canada, 601 Booth St., Ottawa, ON, K1A 0E8 Canada Publisher: Association of Environmental & Engineering Geologists First Online: 02 Mar 2017 Online ISSN: 1558-9161 Print ISSN: 1078-7275 Copyright © 2003 Geological Society of America Environmental & Engineering Geoscience (2003) 9 (3): 201–212. https://doi.org/10.2113/9.3.201 Article history 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 JOHN J. CLAGUE, STEPHEN G. EVANS; Geologic Framework of Large Historic Landslides in Thompson River Valley, British Columbia. Environmental & Engineering Geoscience 2003;; 9 (3): 201–212. doi: https://doi.org/10.2113/9.3.201 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 SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract At least eight large landslides occurred in Thompson River valley south of Ashcroft, British Columbia, between 1880 and 1982. The landslides were slow-moving translational slides and slumps, and sudden-onset, rapid flowslides. Some of the landslides disrupted trans-continental rail traffic and blocked Thompson River, creating short-lived upstream reservoirs. Most of the landslides occurred in a 10-km reach of Thompson valley, within a thick Quaternary valley fill dominated by glaciolacustrine sediments. Failure occurred on the steep walls of an inner valley that formed during the Holocene when Quaternary sediments filling the broader Thompson River valley were incised. The valley fill sequence consists dominantly of permeable sediments, the exception being a unit of rhythmically bedded silt and clay near the base of the Pleistocene sequence. Large landslides are restricted to areas where this silt-clay unit is present. Failure occurred within, or at the top of, this unit. The landslides may have been triggered by irrigation of benchlands above the river. Irrigation commenced in the 1860s, shortly before the first known large landslide occurred. Early irrigation added large volumes of water to the normally dry Quaternary sediment fill, possibly elevating pore pressures at the top of the rhythmically bedded silt-clay unit. Large landslides may occur in the future in the study area if irrigation is not carefully controlled or if climate becomes wetter for periods of years or decades. Such landslides would probably involve reactivation of nineteenth- and twentieth-century landslide deposits. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.