Late Wisconsinan paleosols and macrofossils in Chehalis Valley: paleoenvironmental reconstruction and regional significance

A subalpine coniferous forest occupied the Chehalis Valley before 19,980 ± 70 years BP (UCIAMS 126600), according to plant and insect macrofossils and paleosol evidence preserved in Late Pleistocene-aged sediments. The paleoclimate was similar to the modern Engelmann spruce-subalpine fir (ESSF) ecosystem that occurs at high elevation with cold and wet climates today. The Chehalis Valley evidence challenges the interpretation that the Coquitlam Stade and the Port Moody Interstade were regional and driven by climate change. Coquitlam till is absent from Chehalis and there was a coniferous forest present when other areas in southwest British Columbia were covered by Coquitlam Stade ice.