British Columbia’s Eocene Lakes and Forests: New Perspectives on Temperate Islands from a Past Greenhouse World
Dr. David R. Greenwood, Brandon University, Manitoba
During the early Eocene, about 55 to 50 million years ago, warm climates extended into Canada’s Arctic as far north as Ellesmere Island, supporting biologically rich forests of conifers, broadleaf trees, and a diverse fauna. In the south, climates were subtropical to tropical. In the 1890s, fossil palm fronds were routinely collected from Eocene-age rocks in what is now downtown Vancouver. Inland from Vancouver, however, are many other plant fossil sites that tell a story of a much cooler climate where the plant and animal fossils reconstruct Eocene forests with a temperate character, much like the Arctic Eocene forests.
In this talk, Dr. Greenwood discusses the history of study of these cooler highland Eocene fossil sites starting with J.W. and G.M. Dawson and important contributors from Canadian and U.S. universities over the 1950s to present day, highlighting how our understanding of the age, and the kind of questions being asked have changed as successive generations of palaeobotanists have studied the fossil leaves, seeds, fruits, flowers, and conifer cones. Once considered middle Eocene, these interior British Columbia fossil sites are now known to fall within the Early Eocene Climatic Optimum, a sustained period of globally warm climates from 52 to 50 million years ago. The plant fossils reveal ancient connections between East Asia and North America. Using case studies, Dr. Greenwood shows the early Eocene temperate forests of British Columbia were much more diverse than those of present day eastern North America, under climates not that different from modern-day Seattle and Portland.