A new set of seismic reflection and refraction lines has been interpreted regarding the basement and crustal structure of the southern Agulhas Plateau. A large number of extrusion centres were identified. Lava flows dip away from those extrusion centres and form subparallel-stratified sequences. We interpret those extrusion centres as the result of excessive volcanism in course of the separation of the southern Agulhas Plateau from the Maud Rise. Since the sedimentary layers appear to be little affected by the volcanism, that episode obviously ceased before onset of sedimentation in Late Cretaceous times. We have not found evidence for continental fragments within overthickened, predominantly oceanic crust. We therefore propose that the Agulhas Plateau belongs to the world-wide suite of Large Igneous Provinces (LIP) of predominantly oceanic origin. ¿ 1999 American Geophysical Union