Nick Zentner, a charismatic geology professor from Central Washington University, reveals a dynamic picture of the Greenway’s natural history in “I-90 Rocks.” Using stunning photos and eye-catching illustrations, the new video series is a roadside geology guide for the Greenway and beyond. Don’t have a geology degree? Not a problem—these videos are designed to make learning about the Greenway’s past easy and fun!
The Greenway hosts so many amazing geologic stories. Seattle’s hills were created during the Ice Age by the Puget Lobe, leaving drumlins composed of glacial rocks. Slicing through the glacial till is the Seattle Fault, first recognized in the 1960’s. Much of I-90 has been built above the Seattle Fault, with the Issaquah Alps south of the fault getting lifted higher each time there’s an earthquake on the fault.
Lake Washington and Lake Sammamish are remnants of much larger glacial lakes that dominated the Puget Lowland as the ice sheet was melting back to Canada. The ice sheet over Seattle extended to the base of the Cascades, where impressive glacial deposits at North Bend mark the eastern edge of the ice. Each rock has a story tell about the early Cascades – or even what Washington was like before the Cascades began forming.
Nine video episodes have been written for the journey across the state. The first three installments (Seattle, Seattle to North Bend, and Snoqualmie Pass) have been completed and are currently available online (see links below). The remaining six episodes are in various states of completion. The duo hopes to complete filming by the end of the year.
Look for the next two episodes (Cle Elum, Kittitas Valley) to be posted online this fall. The Cle Elum episode tracks the Yakima Valley Glacier that used to flow east from the Cascade crest, highlights the rich coal deposits of the area, and even features the Straight Creek Fault – an extinct fault similiar to California’s San Andreas Fault. The Kittitas Valley episode marks the end of the big glacier, discusses the formation of central Washington’s valleys, and includes the Ellensburg Blue Agates and Liberty Gold Mines.
Professor Zentner and photographer Tom Foster were inspired by Phil Fenner’s online geology guide “A Geo Tour of I-90.”