Twenty-two sites from two small exposures of basalt of probable Eocene age immediately east of the Olympic Mountains have the following mean paleomagnetic direction: declination, 176.5¿; inclination, -66.5¿; circle of 95% confidence, 8.6¿. This is the only paleomagnetic study of pre-Miocene rocks anywhere in western Washington or Oregon that matches the polar wandering curve for North America. However, a marked fanning of paleomagnetic declinations around the Olympic core suggests that concordance in this case is fortuitous and results from oroclinal bending during or immediately after Olympic orogenesis. Creation of the Olympic Mountains involved accretion of thickened basaltic crust followed by underthrusting of large quantitites of oceanic sedimentary debris, as the Farallon plate pressed northeastward into a recess formed by the thick crystalline blocks of Vancouver Island and the North Cascades.