The Border Ranges fault separates structurally complex accreted Cretaceous rocks from less deformed middle or late Paleozoic and younger rocks in the Cook-Shelikof basin. Gravity, satellite altimetry, magnetic and seismic reflection and refraction data were used to investigate this fault. Gravity data give the clearest indication of its presence and crustal structure. Proposes that during the Late Cretaceous, motion along the Border Ranges changed from strike slip to reverse. Cenozoic rocks near the fault show no evidence for post-Cretaceous fault movement. -after Authors