On Sat. Nov. 20, 2021, Doug Clark, Professor of Geology at WWU, Bellingham presented Lidar data and new stratigraphic, lake sediment, and radiocarbon constraints shed new light a long-standing dispute about the timing and nature of the last major events of the Cordilleran ice sheet in the Fraser Lowland. These new data paint a remarkable picture of glacier advances and retreats interleaved with rises and falls of local sea level during the closing phases of the Pleistocene ice age.Following its initial retreat from the Puget Sound, the ice sheet briefly readvanced into the Salish Sea near Bellingham, Washington about 14,500 years ago.Immediately afterwards, the ice retreated north of the International Boundary long enough for forests to establish in deglaciated lowland sites.Then, shortly following this retreat, local relative sea level (RSL) rose rapidly by ~20–30 m (~65-100 ft) about 14,000 yr ago, inundating the U.S. portion of the lowlands up to ~130 m above modern sea level.While RSL was at its highest, the ice sheet readvanced across the border to nearly the same extent as the earlier event.
By about 13,000 yr ago, ice had retreated north of the border, and local RSL had fallen to within ~4 m of modern SL. A layer of possible loess (windblown dust) in sediments in Squalicum Lake suggests the ice sheet readvanced for a third and final time between 13,000 and 11,150 yr ago, constructing a moraine ~8 km south of the border town of Sumas, Washington. A series of unusual channels just beyond this final moraine indicate that the ice sheet experienced a catastrophic outburst flood immediately before the ice sheet stagnated and disappeared.
Mass extinctions in geologic time: Implications for the past, present and future
During the past 400 million years of life, evidence of five mass extinction events have been detected in the fossil record. These events caused world-wide destruction and led to collapse of whole ecosystems, producing profound changes in Earth’s history and forever altered the evolution of life. Mass extinctions constitute one of the grand “unifying themes” of our planet. Study of the strata, rocks and ancient fossils related to these episodes of massive dying are revealing much insight into not only the history of our planet, but also evolution and the directionality of life. Such geologic and paleontologic studies can teach us to better understand, slow and possibly reverse the 6th mass extinction now underway. This lecture was presented via Zoom on Sat. Oct. 9th at 4 pm.
George Stanley is Professor Emeritus and former Director of the University of Montana Paleontology Center. In the Dept. of Geosciences at Montana, he taught and conducted research in paleontology and geology for 35 years. His research has helped clarify mass extinctions, the evolution of reef structures and modern and ancient coral lineages.
He is a Fulbright Fellow and former Geologist and Research Associate at the Smithsonian Institution’s Museum of Natural History, a Fellow of the Geological Society of America, Organization for Tropical Studies, and American Association for the Advancement of Science. He has authored more than 300 professional publications and several books. His research has taken him to western Canada, northern Mexico, the Peruvian Andes, Germany, Austria, New Zealand, Japan and China. Now largely retired, he lives in Port Townsend where he enjoys hiking, nature and playing guitar.
One-day field trip (car caravan) to see the Elwha River’s response to removal of its two dams 7 years ago (2014). We’ll see the lower dam site, one of the dissected lake basins, sedimentation along the river’s mid-reach and the build out of the river’s delta. Ian Miller, our geologic guide, is with the SeaGrant program of the University of Washington, but resides in Port Angeles close to the action. In addition, we recruited Keith Denton to talk about the main reason for the dams removal (fish) Keith is a Fisheries Consultant and will discuss the recovery program that has brought salmon back to the Elwha River after a century.
Leaders: Ian Miller, Coastal Hazards Specialist, Washington Sea Grant, Port Angeles
Keith Denton, Fisheries Specialist and Consultant, Sequim
Michael Machette, Quaternary Geologist (retired), Port Townsend
Objectives: Visit ground zero of the largest dam-removal project in the world and one of the largest ecological restoration projects ever attempted. See the developing shore-line and take a tour of three important restoration sites along the Elwha River. Enjoy the outdoors and have enlightening discussions (socially distanced).