How do the valleys form in a basin-range province? As extension and uplift occur, erosion and sedimentation happen simultaneously but at slower rates. As extension slows down, erosion and sedimentation can overcome mountain building. A typical rift features inlude down-dropped faults and uplifted escarpments. The valleys become filled with erosional sediment. https://www.iris.edu/hq/inclass/animation/basin__range_deformation_erosion__sedimentation | EarthScope Consortium