Extensive geomorphic mapping in the northern Martian fretted terrain of Deuteronilus and Protonilus Mensae shows details of the waste-dominated landform association in this region. Wasting appears to have occurred along the cratered terrain boundary (CTB) at the expense of old cratered terrain. North of the boundary remnants of old cratered terrain occur as island mesas surrounded by extensive debris aprons. Quantitative study using principal components analysis (PCA) reveals distinct spatial variations in the morphology of waste forms in the region and supports the qualitative interpretations made during geomorphic mapping. These organized spatial patterns occur with respect to longitude and latitude, and therefore with reference to distance from the CTB, and provide clues to the degradational history of the region. Analyses of the individual landforms irrespective of their location to the CTB indicate strong structural control of their form. Mesas appear to evolve from equant forms to narrow ridges with large debris aprons after they become detached from the old cratered terrain. The success of PCA in explaining patterns in degradational landforms suggests that PCA may be an important technique in quantifying the geomorphic evolution of the ''Martian'' surface.