Recent work has demonstrated that modern drainage systems on rifted continental margins may be the product of ancient lithospheric doming in areas of flood-basalt magmatism. This uplift is thought to reflect the existence of widespread mafic underplating and excess melt generation at rift zones. Here I show that uplift due to the initiation of a thermal anomaly (plume head) in the asthenosphere may be evidenced by the formation of discrete rift structures and persistent paleodrainage (sediment dispersal) patterns for up to 150 m.y. priorto the commencement of igneous activity and final continental breakup. Volcanism thus occurs as a comparatively late stage geochemical response to the long-term residence of hot plume material beneath continental mantle lithosphere.