Relief has been calculated over four orders of length-scales (75 m to 800 km) for several drainage basins along the south-eastern border of Massif Central, an asymmetric plateau edge feature. Relief is not uniform over the length-scale domain, but rather appears as smooth at small and large scales, and rough at meso-scale. This heterogeneous behavior is interpreted as a consequence of the different processes that shape topography at such ranges of scales. The threshold between small and meso scales is rather well constrained for all basins (400--500 m), and may represent the limit where channel networks appear, while the threshold between meso-scale and large scale varies with geological context: where relief is fault controlled (Mediterranean drainage basins), the threshold value is of the order of 15--20 km. Where topography is flexurally controlled (Atlantic drainage basins), the threshold value is different (40--80 km).¿ 1997 American Geophysical Union