KARST LANDSCAPE EVOLUTION ON VANCOUVER ISLAND, BRITISH COLUMBIA, CANADA

The regional geology, tectonic history and past glacial events have been significant in the evolution of the predominantly mountainous karst landscapes of Vancouver Island, on Canada’s Pacific Coast. The uplift history, sea level changes and isostatic rebound are also important considerations. Previous research within caves of Vancouver Island points towards at least two periods of speleothem growth during the last and present interglacial periods (55,000 – 33,000 years BP and less than 15,000 years BP, respectively). Some additional cave morphological evidence suggests even older ages (>100,000 years BP) for subsurface karst development. Many surface karst features are likely post-glacial (<14,500 years BP), with earlier features either being erased by glacial erosion or buried by glacial drift of varying thickness. However, it is also possible that glaciations in some areas of Vancouver Island may have altered or enhanced development of surface and subsurface karst features by meltwater channeling and other processes. Research is underway to map some of the representative karst landscapes, and to collect data on their characteristics, bedrock structures and surficial geology. Cave morphological information, including cave patterns and cave passage positions/orientations will be combined with surface bedrock/karst geology and topographic/elevation data to develop a three-dimensional interpretation of the karst landscapes. It is anticipated that this research work will lead towards a ‘conceptual model’ for karst landscape evolution on Vancouver Island, and possibly aid in unraveling other aspects of the glacial processes, climate change and tectonic history of Canada’s Pacific Coast.