Conventional studies of oceanic structure and evolution are inevitably hampered by the difficulties with sampling the crust in the third dimension. Subsurface studies with deep seismic techniques provide some measure of understanding below the seafloor. Ophiolite studies, however, can provide a vast body of knowledge with regard to the deeper structure and crustal compositions, which is unattainable in the deep sea. In turn, many of the recent regional and detailed structures identified at mid-ocean spreading systems such as ridge segmentation patterns and ridge axis discontinuities, now form a significant contribution to recent studies of ophiolite complexes.