Is the Yachats basalt related to Yellowstone?
The hard and dark-colored rock (basalt) that underlies Yachats and Cape Perpetua indicates that there was once a volcano here. When this rock erupted 36 million years ago as molten lava, Oregon looked much different. There were no Cascade volcanoes, and the explosive Yellowstone hotspot volcano might have been close by! My talk explores results of recent research on the geologic history of the Pacific Northwest and the link between Yellowstone and Cape Perpetua. This presentation is for the interested non-geologist.

The talk begins with a quick review of plate tectonics, explains what a hotspot is, and describes how seafloor sediments accumulate at the edges of continents when plates collide. Then I discuss recent geologic research that has improved our understanding of the jumbled collection of rocks that composes the Pacific Northwest. By studying the history of the movements of the North American and Juan de Fuca tectonic plates, some geologists have concluded that today’s Yellowstone hotspot was just to the south when the Cape Perpetua volcano erupted. Adding to the geologic complexity is the northward movement and rotation of Oregon. Geologic discovery and discussions are ongoing. This talk presents some recent discoveries and remaining questions.


Meet the speaker:

David Muerdter is a geologist with 40 years of industry and teaching experience culminating as an instructor of a course about the velocity of sound in rocks. He is now retired and enjoys volunteering at the Cape Perpetua Visitors Center, the Hatfield Marine Science Visitors Center, and the Oregon Coast Aquarium. He has a BS in geology from Oregon State University and a PhD in geologic oceanography from University of Rhode Island.

Dave is also a wonderful volunteer of the Cape Perpetua Collaborative. Dave contributes over 30 hours annually to the Cape Perpetua Collaborative. We are so thankful to have Dave!



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