Saturday, March 6, 2010

Oregon's geologic history

This fascinating site from the Oregon Department of Geology and Mineral Industries (ODGMI) showcases the geologic history of the state. This site explains the fundamentals of plate tectonics and then illustrates in 20 progressive maps the incremental stages of land formation within the boundaries of the state beginning 400 million years ago. This progression provides a clear overview of the accretive geologic history of the state.

The resource linked above is supplemented by this project seeking to understand the Missoula Floods. As this page of the ODGMI's site shows, there are some extensive deposits from the Missoula Floods in much of the Willamette Valley and along the Columbia Gorge in northern Gilliam, Morrow, and Umatilla counties.



  1. An upcoming event on this topic:

    "Visualizing the Cataclysmic Missoula Ice Age Floods: A Super Computer Simulation"

    Roger Denlinger, U.S. Geological Survey's Cascades Volcano Observatory

    Wednesday, May 19th, 7:00 PM

    Museum of the Oregon Territory (3rd floor), 211 Tumwater Drive, Oregon City

    Roger Denlinger is one of the developers of a new computer model to simulate the massive floods that repeatedly carved the mid-Columbia landscape between 15,000 and 18,000 years ago. His talk will include the simulation, which is titled, "Ancient and Catastrophic Flooding from Outbreaks of Glacial Lake Missoula: the Movie."

    A February 20, 2010 article in the Oregonian describes Dr. Denlinger's work:

    "Floodwaters rise more than 1,000 feet as they slam into the Columbia River Gorge from the east. The torrent blasts through the narrows at 60 mph, carrying truck-size boulders and house-size icebergs. Reaching Portland, water loaded with gravel and dirt roils to a depth of 400 feet, leaving tiny islands at the summits of Mount Tabor and Rocky Butte.

    "Geologists have spent decades piecing together evidence to tell the story of the great Missoula floods that reshaped much of Oregon and Washington between 18,000 and 15,000 years ago.

    "Now scientists have found a way to travel back in time to watch the megafloods unfold, in a virtual bird's eye view. Their computer simulation displays the likely timing and play-by-play action, starting with the collapse of an ice dam and outpouring of a lake 200 miles across and 2,100 feet deep."

    For more information on the Missoula Floods, visit the Ice Age Floods Institute.

  2. OPB's Think Out Loud program will feature the Missoula Floods on Nov. 16, 2010. I'll be tuning in for sure!