Various styles of seismic imaging provide evidence for variability within major lithospheric blocks such as the cratons of Australia. The crustal components show clear differentiation that appears to link to the properties of the mantle lithosphere. Although some cratonic sutures have a clear impact on structure in the uppermost mantle, surface wave tomography does not provide support for the concept of near vertical link zones penetrating the full lithosphere. The transition from a craton to a Phanerozoic belt may not have a simple configuration in depth. In eastern Australia there is evidence for a set of steps in lithospheric thickness whose configuration differs markedly from the surface "Tasman Line" marking the easternmost extent of Precambrian outcrop. The substructure of the lithosphere provides much information on the evolution of the present assemblage. The subtle features appear most clearly when information from multiple styles of seismic probes can be combined, so that both large and small spatial scales can be resolved.