Current stress solutions for Mars match the long wavelength signal of present day topography and gravity but fail to match many surface faults, including the normal faults in northern Claritas Fossae north to Tantalus and Alba Fossae. A deviatoric stress field associated with horizontal gradients of gravitational potential energy (GPE) provides an excellent fit, as measured by objective functions, to many of the normal faults in the western Martian hemisphere as well as wrinkle ridges circumferential to Tharsis; ~70% of the faults have a misfit ≤ 0.1. The fit of faults to the GPE-derived stress field reflects the thermal state of the planet at the times of faulting, and suggests that at such times elastic thicknesses and membrane stresses were small, and topography was supported by buoyancy forces.