Progressive movement resulting in displacements that can be resolved into horizontal and vertical components is recorded in the fault–displacement of flights of river terraces, the oldest terraces showing the greatest displacements. No unique interpretation of the sequence of events is possible, as illustrated from a hypothetical example, but the vertical and horizontal components of individual movements can be deduced according to a stated rule. In associating fault movement and river downcutting, the heights of the terraces on the lower side of the fault scarp should be used, not those on the higher side. As a result it is concluded that at the Wairau River downcutting and faulting do not show the linear relation deduced by Wellman; as a preferred interpretation, the rate of faulting is supposed to have been substantially uniform while the rate of downcutting has diminished, since the formation of the highest, depositional, surface in the flight. The depositional surface is typical of the highest in many terrace flights, and where these are the principal outwash aggradational surfaces of Last Glaciation age, or their correlatives, 20,000 years is thought a closer estimate of age than the 10,000 years used previously; previous estimates of the rates of fault movement are correspondingly halved.