CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Blais-Stevens, A.; Schwab, J.W.; Geertsema, M.; and Clague, J.J.
Date : 2006.
Title : Paleo-environmental indicators from the Khyex River landslide site, northwestern British Columbia.
Publication : Joint Annual Meeting of the Geological Association of Canada and the Mineralogical Association of Canada. University of Quebec in Montreal (UQAM) May 14-17, 2006.
Issue :
Page(s) :
Abstract
On November 28, 2003, at 12:30am (PST), a low-gradient, extremely rapid, flowslide occurred at the Khyex River, 35 km east of Prince Rupert in northwest British Columbia. The landslide displaced 4.7 Mm3 of sediments over an area of 32 ha and severed a natural gas pipeline, leaving the communities of Prince Rupert and Port Edward without heat for 10 days. The failure occurred in sensitive, rhythmically laminated, glaciomarine silts and clays. The landslide exposed a rich assemblage of well preserved marine fossils, including barnacles anchored to the bedrock valley wall. Bivalves and barnacles were also exposed in sediments in the head scarp and on boulders and cobbles in the displaced material. In addition to the unusual characteristics of the landslide, the well-preserved paleo-barnacle unit in the slide bowl suggests that the landslide began as a retrogressive failure at the riverbank, but evolved into a flake-slide where the barnacle-rich unit was rafted intact. The presence of barnacles (Balanus crenatus) in growth position suggests a non-turbid marine environment with a shoreline at about 30 m asl ca. 10,400 ± 40 14C yr BP). The barnacles anchored on rock are overlain by silts and clays containing sand lenses rich in bivalves and gastropods, including Hiatella arctica and Lottia digitalis. The bivalve assemblage indicates a cold, turbid, brackish, intertidal environment. The silt and clay unit grades upward into a massive sand unit, containing woody debris dated to 10,285 14C ± 30 yrs BP. The massive sand is unconformably overlain by bouldery colluvium.
Bibliography of Canadian Geomorphology