Geologic and geophysical evidence from western Klamath Mountains, California, provides quantitative information on the shape and regional subsurface extent of the Orleans fault. This major Jurassic thrust fault lies beneath all exposures of the western Paleozoic and Triassic belt within the study area and mainly dips gently or is subhorizontal. The regional extent of the juxtaposition of different units across the fault implies a minimum horizontal displacement of 110 km due to westward overthrusting. The fault cuts the Wooley Creek batholith, which indicates that thrusting took place after intrusion at 163±3 Ma. The shape of the fault near Condrey Mountain is consistent with post-thrusting Neogene uplift of the Condrey Mountain dome and suggests a minimum of 6 km of differential uplift.