We present a statistical analysis of the distribution of large scale topographic features on comet 67P/Churyumov-Gerasimenko . We observe that the cumulative cliff height distribution across the surface follows a power law with a slope equal to -1.69 \pm 0.02 . When this distribution is studied independently for each region , we find a good correlation between the slope of the power law and the orbital erosion rate of the surface . For instance , the northern hemisphere topography is dominated by structures on the 100 m scale while the southern hemisphere topography , illuminated at perihelion , is dominated by 10 m scale terrain features . Our study suggest that the current size of a cliff is controlled not only by material cohesion but by the dominant erosional process in each region . This observation can be generalized to other comets , where we argue that primitive nuclei are characterized by the presence of large cliffs with a cumulative height power index equal to or above -1.5 , while older , eroded cometary surfaces have a power index equal to or below -2.3 . In effect , our model shows that a measure of the topography provides a quantitative assessment of a comet ’ s erosional history , i.e . its evolutionary age .