Portland sits in a flat basin, with northwest-oriented faults where it meets the rugged terrain of the Coast Range. Those faults tend to experience compression as well as lateral movement due to the combination of tectonic forces. Long-term fault movements often leave an unambiguous, linear mark on the landscape, though the prodigious moisture and vegetation in this area do a pretty good job of obscuring things. Still, some of these faults are identifiable on the landscape if you know how to look.
That includes the Gales Creek fault 35 kilometers (22 miles) west of Portland. A Portland State University team