The Ancient Cratered Terrain

Abstract

While the heavily cratered upland plains which lie south of the line of dichotomy bear some similarities to the lunar highlands, they show widespread evidence for a much more extensive history of modification than has occurred on the Moon. Early impact cratering left a very obvious imprint on both worlds while subsequent impact erosion severely degraded the more ancient craters and basins. On Mars, however, fluvial and aeolian activity, volcanism, tectonism and non-impact erosion each has played an important part in bringing the highland plateau to its present geomorphological state. Thus, while a superficial look at a few Viking images of the upland hemisphere suggests a lunar-like surface, closer inspection reveals not only a difference in the nature of the cratering record but also in the morphology of the craters themselves (Fig. 6.1).