ABSTRACT This field guide is for a three-day trip from Portland to Klamath Falls, Oregon, and back, traversing many of the physiographic provinces in Oregon, including the Columbia River, the Willamette Valley, the Western and High Cascade Mountains, the High Lava Plains, and the Basin and Range. Geologic field stops on Day 1 will be made along the drive to Klamath Falls at Salt Creek Falls and Crater Lake, and will include short discussions of Oregon's geological history and a brief introduction to geothermal resources in the state. Day 2 includes an extensive introduction to geothermal resources in Oregon and how these relate to Oregon geology, with tours to examine how the Oregon Institute of Technology, the City of Klamath Falls, and several local businesses in the Klamath Falls area use a local geothermal resource. Day 3 is devoted to the return trip to Portland, and will include geological stops at Newberry Crater, Crooked River Bridge, and Mount Hood, with more discussions of geology, geothermal resources, and geothermal exploration in Oregon.