The imprint of time on Canadian soil landscapes

The imprint of time on Canadian soil landscapes reflects the strong influence of repeated Quaternary glaciations, with most soils having formed on Late Pleistocene glacial sediments, and to a lesser extent, Holocene non-glacial sediments. Soil chronosequences in these youthful landscapes seldom span the full Holocene, and have been documented principally in areas of coastal isostatic uplift and shoreline evolution, as well as on recessional moraine sequences in the Cordillera. These chronosequences have placed quantitative constraints on rates of podzolization in environments ranging from coastal temperate rainforest to subarctic. Longer sequences, involving soils and relict paleosols on Pleistocene morainal and glaciofluvial surfaces in the central Yukon Territory, record more complex legacies of pedogenesis and landscape evolution, but with much coarser time control and many potentially confounding influences of climatic change and disturbance processes. Older weathered bedrock and regolith can make significant contributions to soil parent materials in several settings: (1) in favoured locations where local conditions protected these materials from glacial erosion in southern Canada, (2) beyond the maximum limits of glaciation, principally in northwestern Canada, and (3) in the Arctic, where cold-based, non-erosive ice allowed preservation of these materials. Closer collaborations between pedologists and other Quaternary scientists will be needed to ensure a more complete understanding of these complex pedogenic legacies in Canadian landscapes.