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Willamette Basin Geology and Geography

Do not let the bucolic appearance of the Willamette Basin lull you into the feeling that this paradise has been tranquil throughout time. The rolling valley cradled by the mighty Cascades to the east and the Coastal Range to the west is the result of a torrid geologic past including the movement of an oceanic plate right under your feet, volcano eruptions with some of the ash in the valley located from as far away as the ancient Mount Mazama, now with its topped blown off and filled by Crater Lake, and a giant flood from the ancient ice-dammed Lake Missoula located in Montana.

The aesthetically pleasing mixture of farmland, forests, and many small towns and cities that make the Willamette Basin unique in the United States are also the result of a torrid geographical history. Oregon's legendary land use laws were passed in the early 1970s to preserve the unique quality of life and balance growth with the preservation of high value farmland and underlying soils and forests. The hard won 19 Statewide Planning Goals that every county strives to include in their comprehensive plans are currently being reevaluated as private property owners file for land development claims under Measure 37 (passed in 2004) thus upsetting over 30 years of land use planning which has served as a beacon for land use planning across the globe.

Change is inevitable in geologically young and geographically unique landscapes.

Introduction authored by Todd Jarvis, Senior Researcher, Institute for Water and Watersheds, Oregon State University