The stratigraphy, palynology, and climatic significance of pre-middle Wisconsin Pleistocene sediments, southern Vancouver Island, British Columbia

Abstract

Palynological investigations of organic-rich sediments from the Muir Point Formation and basal Cowichan Head Formation on southernmost Vancouver Island have identified seven pollen zones. Modern pollen spectra from the extant vegetation in southwestern British Columbia aid in interpreting paleoenvironments from the fossil pollen assemblages. Six of the pollen zones (MP-1, MP-2, MP-3, MP-4, CB-3, and CB-4) are from the Muir Point Formation and are beyond the range of ¹⁴C dating. They record evidence of vegetation and climate during either the last interglacial or penultimate interglacial (or some much older interglaciation) when conditions were at first warmer and (or) drier than at present, then succeeded to cooler and (or) moister conditions. The seventh and youngest pollen zone (MP-5) provides evidence of subalpine to near tree-line vegetation growing in cool–cold conditions before 43 000 years BP, during the early Olympia nonglacial interval. These pollen zones and interpretations are in part correlative with established zones from adjacent Washington and eastern Vancouver Island.