Category: Speakers

2024-03-23 Brian Sherrod — New Findings on Earthquakes of Salish Lowland with Tree Analysis

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We enjoyed hearing in-person USGS geologist, Dr. Brian Sherrod, on February 24, 2024 and by Zoom March 23.

THE LECTURE:  High-resolution dating of a multi-fault earthquake and earthquake recurrence in the Salish Lowland

See Sept. 2023 Science Advances article: https://www.science.org/doi/10.1126/sciadv.adh4973

Dr. Brian Sherrod discusses new evidence for a multi-fault rupture. This rupture occurred along the Seattle (SFZ) and Saddle Mountain (SM) faults in the winter of 923-924 CE. He presents new evidence for a proto-historic earthquake on the Seattle fault (in the 1830s), and he talks about recurrence of large earthquakes in the Salish Lowland. He employs photographs, USGS mapping, lidar measurements, charts, and graphs to elaborate his points. Brian is a master story-teller, and his lecture will explain how this important event was detected.

For a complete version of the research paper:  Black, Pearl, et al., 2023, A mulitfault earthquake threat for the Seattle metropolitan region revealed by mass tree mortality:  Science Advances 9, Sept. 2023

THE SPEAKER:

Dr. Brian Sherrod is a Research Geologist and Pacific Northwest Regional Coordinator for the USGS Earthquake Hazards Program, based in the Department of Earth and Space Sciences at the University of Washington.

He received his BS in Geology from James Madison University in Virginia, his MS in Geology from the University of Pittsburg, Pennsylvania, and his PhD in Geological Sciences from the University of Washington. His main area of research is paleo-seismology:  finding evidence of past earthquakes in the Pacific Northwest using geological records. Much of his work uses lidar. His recent projects include looking for evidence of surface rupture along faults in central and western Washington, coastal uplift, and subsidence along faults in the northern Salish Lowland.

 

 

2024-04-20 Ralph Haugerud — Glacial Landscape of Puget Sound

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Post-Mortem of Southern Cordilleran Ice Sheet

Quimper Geological Society welcomes back USGS geologist, Ralph Haugerud, to present new understanding of glacial topography from lidar imagery. He will focus on what happened when the ice melted.Join us (in person) at the First Baptist Church, 1202 Lawrence Street, Port Townsend, Washington – Saturday April 20 at 4 pm. The event will also be filmed and posted for viewing afterwards.

The Lecture: Post-mortem of the southern Cordilleran Ice Sheet

Death of an ice sheet can have many causes, as shown by retreat of the southern Cordilleran Ice Sheet about 15,000 years ago. East of the Cascades, the margin of active south-flowing ice retreated north as less snow fell and more melted. West of the Cascades, the Juan de Fuca lobe of the ice sheet appears to have floated away in response to rising sea level, perhaps without a proximal climatic cause. Collapse of the Juan de Fuca lobe diverted ice from the Puget lobe, which consequently stagnated at its margin and rapidly melted back. Later Sumas ice readvance in the Fraser Lowland may reflect stabilization of the remnant ice sheet by grounding as local sea level fell, followed by climate-driven retreat.

For a more detailed abstract, please see Ralph Haugerud’s detailed abstract Jan2024.

The Speaker 

Ralph Haugerud is an exceptional geologist. Many describe him as a structural geologist and geologic mapper interested in the evolution of the Pacific Northwest, and many know about his popularity from being featured on Nick Zentner’s programs.

Ralph is a Seattle native, with BS and MS degrees from Western Washington University and a PhD from the University of Washington. He began his career looking deep in the Earth’s crust at gneiss and tonalite in the North Cascades, moved on to study turbidites, then glacial till, and now spends much of his time looking at lidar topography. He is employed by the USGS and lives in Wenatchee, Washington.

2023-04-29 Skye Cooley: Calcrete and Soil-Climate Evidence

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The Lecture: Soil-climate evidence for timing of the Cascade uplift and creation of its rain shadow

Calcrete is a CaCO3-rich hardpan paleosol that forms in dry, stable landscapes of the world. Calcrete in eastern Washington cements a 20-m-thick interval across three geomorphic domains: Palouse Hills, Channeled Scablands, and Yakima Fold Belt. The sheet-like calcrete deposit encloses ancient Scabland flood gravels and defines a regional paleosurface that has been bent and broken by Quaternary faults. Calcrete overprints primarily lowland alluvial deposits (ancestral Columbia-Snake River floodplain) and basaltic alluvial fan gravels shed from fault-bounded ridges. Thick layers of pedogenic carbonate accumulated during the Pleistocene, between about 1.8 million years ago to about 40 thousand years ago, but older cements at somewhat deeper levels date back to ~7 million years (late Miocene). The appearance of arid-land calcrete in eastern Washington coincides with the topographic rise of the Cascade Range and establishment of a strong rain shadow east of the divide. This lecture shed new light on this lesser-known part of eastern Washington’s stratigraphy.

The Speaker

Skye is a field geologist who specializes in mapping, paleosols, and geomorphology. His work focuses on the interplay between tectonics, topography, and climate. Skye received his BSc. in Geology from Whitman College and his MSc. from the University of Wyoming. He has been a Soil Scientist for the Colville Confederated Tribes and taught Geosciences at Boise State University.

Currently, Skye is mapping the surficial geology of the Mission Valley in northwest Montana and sorting out the geomorphic history of calcretes in Eastern Washington. Skye’s hobbies include woodworking, nordic skiing, and motor-cycles. Skye is married to Hilary, manager of the Grizzly Bear Program for the U.S. Fish and Wildlife Service. They live with their hound dog, Lucy, in northwest Montana.