The Lecture
Subduction-related late Quaternary tectonic uplift and sea-level change in the Pacific NW and around the Pacific Rim
This was a Zoom-only lecture.
Quimper Geological Society welcomed Dan Muhs, an emeritus USGS geologist. He provided marine terraces as evidence of tectonic uplift along the Pacific Ocean plate.
In 1979, Seiya Uyeda and Hiroo Kanamori introduced a tectonic model with two end members of a subduction-boundary continuum: the “Chilean” type (shallow dip of the subducting plate, great thrust events, compression, and uplift of the overriding plate) and the “Mariana” type (steep dip of the subducting plate, no great thrust events, tension, and little or no uplift). The concept has been used to explain variable rates of Quaternary uplift around the Pacific Rim, and the paper has been cited over a thousand times since its publication in the Journal of Geophysical Research. We now have a sufficient number of dated late Quaternary marine terraces from around the Pacific Rim to test the veracity of this model. In this presentation, well-dated emergent shorelines of the Pacific Rim was explored, from South America, North America, the Aleutians, Japan, and the Marianas.
About the Speaker
Dan Muhs is an emeritus scientist with the U.S. Geological Survey. He earned B.A. and M.S. degrees from the University of Illinois and a Ph.D. from the University of Colorado. He was a research geologist with the USGS from 1985 until his retirement in 2022. Despite his retirement, Dan remains an active researcher, lecturer, and writer.
Dan’s interests are in the fields of coastal and eolian geomorphology, Quaternary stratigraphy, soil genesis, and paleoclimatology. Most of his work has been in the US (Alaska, western US, and Great Plains), but he has also worked in Canada, Mexico, Caribbean, Spain, and western Pacific. Over the course of his career he has authored more than 150 scientific papers on a diverse range of subjects focused on the Quaternary period, including the origins and history of loess and dune fields, paleozoogeography of marine fossil invertebrates, tests of glacial isostatic adjustment models, and sea-level histories and tectonic uplift rates deduced from emergent marine terraces. Dan has received numerous awards and recognition, including the Geological Society of America Kirk Bryan Award.
Glaciers have shaped much of the Pacific Northwest’s landscape over the past 15,000 years. The Cordilleran ice sheet, repeated ice age floods, and expansive alpine glaciation have left their distinctive fingerprints on the topography of our region. Geologists and cartographers have been mapping and interpreting glacial landforms since the late 19th century. In the past decade, the Washington Geological Survey has created new maps that build upon this rich cartographic history by fusing older datasets and techniques with modern insights and technology, such as lidar.
Daniel Coe has been making maps of the Pacific Northwest for the past two decades. He currently serves as graphics editor for the 
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