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The Capilano Sediments hydrogeological unit overlies the Vashon Drift, except locally where it unconformably overly Quadra Sand. The thickness of the sediments is highly variable ranging < 1 m up to 12 m and locally reaching 25 m in thickness. These marine and glaciomarine deposits, of considerable thickness, are found in coastal areas that had undergone significant glacio-isostatic submergence prior to uplift. They are mostly composed of silt and clay of marine origin. These deposits are considered to be postglacial, but still affected by rapid emergence and influxes of glacial meltwater during early deglaciation. The marine deposits are relatively impermeable due to their fine grain-size. Geochemically there is a decrease in concentration from the base of the Capilano Sediments upwards for Ba, Ca, K, Rb and Zn and there is an increase in the concentration for Cu, Fe, Mn, and V (Knight et al., 2015). |
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