A 140-km-long refraction/wide-angle reflection profile recently recorded by Stanford University and the U. S. Geological Survey imaged the subducting Gorda slab beneath northern California. The profile, which is subparallel to the coast from Cape Mendocino northward, indicates that the North American plate is 13- to 14-km-thick along the coast north of Cape Mendocino. The crust is characterized by relatively uniform, low velocities of ≤6 km/s interpreted as Franciscan rocks. Two strong reflections define the upper and lower boundaries of the subducting Gorda crust. Our data indicate that the subducting Gorda crust thickens northward from Cape Mendocino from 7-km-thick just north of Cape Mendocino to 10-km-thick 120 km to the north. This change in thickness is coincident with a change in velocity from 6.7 km/s south to 6.2 km/s north. Mantle velocities of 7.7 km/s are observed for offsets greater than c. 80 km. We interpret our model to indicate that the Gorda slab is not imbricated on a crustal scale beneath our profile, that sediments and/or a tectonically thickened oceanic layer 2 are present to the north but not in the vicinity of Cape Mendocino, and that proximity to the Mendocino triple junction affects the way sediments are subducted. ¿ American Geophysical Union 1994