Figure 38. Block diagrams illustrating progressive development of transform faults in new oceanic crust at spreading center, influenced by strike-slip movement on pre-existing faults in the separating continental margins of North America and Africa. These continental basement faults are inferred to be associated with lateral ramps in the cover rocks. Cover rocks are transparent in block diagrams. A, Initial upwelling of oceanic crust and offset along continental faults precursory to formation of transform faults. B, Sea-floor spreading, upwarping of continental crust, and additional movement along continental and incipient transform faults. C, Additional spreading and fault movement.