Figure 6. Subfigure A illustrates how Tharsis-driven extension in Bathys Planum might reactivate an antecedent basement fault (black) as a strike-slip fault, causing the observed stairstepping graben morphologies. Green illustrates both the graben and the direction of extension (σ3) implied by the graben’s formation. When the graben intersects with the antecedent structure, the same regional stress field drives a component of throw and heave (in green, perpendicular to the structure) and a component of left-lateral motion (in black, parallel to the structure) that causes similar lateral deformation elsewhere on the fault, driving the aforementioned stairstepping morphologies. Subfigure B shows the mapped faults (other than graben) without the basemap to highlight the curvilinear form of faults.