MUDFLOW OF 1941 AT WRIGHTWOOD, SOUTHERN CALIFORNIA

Abstract

Research Article| May 01, 1953 MUDFLOW OF 1941 AT WRIGHTWOOD, SOUTHERN CALIFORNIA ROBERT P SHARP; ROBERT P SHARP CALIFORNIA INSTITUTE OF TECHNOLOGY, PASADENA, CALIF.; NORTHWESTERN UNIVERSITY, EVANSTON, ILLINOIS Search for other works by this author on: GSW Google Scholar LAURENCE H NOBLES LAURENCE H NOBLES CALIFORNIA INSTITUTE OF TECHNOLOGY, PASADENA, CALIF.; NORTHWESTERN UNIVERSITY, EVANSTON, ILLINOIS Search for other works by this author on: GSW Google Scholar GSA Bulletin (1953) 64 (5): 547–560. https://doi.org/10.1130/0016-7606(1953)64[547:MOAWSC]2.0.CO;2 Article history received: 07 Jul 1952 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 ROBERT P SHARP, LAURENCE H NOBLES; MUDFLOW OF 1941 AT WRIGHTWOOD, SOUTHERN CALIFORNIA. GSA Bulletin 1953;; 64 (5): 547–560. doi: https://doi.org/10.1130/0016-7606(1953)64[547:MOAWSC]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 SocietyGSA Bulletin Search Advanced Search Abstract During early May of 1941 the southern California mountain resort of Wrightwood was partly inundated by surging flows of muddy debris which occurred daily for more than a week. The immediate cause of flowage was rapid melting of deep winter snow. Intense shattering and rapid weathering of the bedrock (Pelona schist) within the San Andreas rift zone at this location contributed materially to preparing debris for flowage.Field studies, eyewitness accounts, and movie films provide the following information. Debris was transported 15 miles by the mudflow, and on a gradient as low as 75 feet per mile at the outer extremity. The flow advanced in successive waves or surges of “slimy gray cement-like” mud containing abundant stones. Velocities of the surge fronts ranged from a few to nearly 15 feet per second and averaged close to 10 feet per second during the more fluid phases. The fronts of the more fluid surges slithered and splashed along about like a rapidly advancing tongue of water. No breaker-like motion was evident, although the top of the front tended to shoot ahead of the base. In more viscous surges a bouldery embankment developed at the front and was shoved along by the material following behind.One sample of the fluid debris had a density of 2.4, indicating a water content of 25–30 per cent by weight. Calculated viscosities range from 2 × 103 to 6 × 103 poises. An average sorting coefficient of 3.94 indicates poor sorting, although somewhat better than in many glacial tills which the flow deposits strongly resemble. Earlier mudflows have occurred here, and others will undoubtedly take place in the future. 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.