The Deep Sea Drilling Project and Ocean Drilling Program have collected a wealth of borehole information on volcanic margins. Seismic data have been kindly provided by the Danish Lithosphere Center, the Norwegian Petroleum Directorate, and Geco-Prakla. Help, comments, and thorough reviews by H.C. Larsen are greatly appreciated. P.A. Symonds, J.B. Diebold, and O. Eldholm further gave constructive reviews. The Research Council of Norway and Statoil have partly financed the study.