Slopes are the fundamental unit of the physiographic landscape. Yet the reasons for variations in their morphology and inferred mode of development are not well understood. The problem is complex, but the slope budget, which results primarily from the interplay of climatically induced factors and structure is significant: where the erosion of the upper slope elements surpasses that on the lower, parallel retreat prevails, but when the reverse is the case, slope decline is dominant. Complications are introduced by such factors as climatic change and fluctuations of baselevel, both local and general. But structural factors can and do override all others.