Cratering history of Miranda - Implications for geologic processes

The terrain of Miranda, which is the least cratered and therefore pressumably youngest of the Uranian moons, encompasses more heavily cratered and coronae regions, of which the former are, again pressumably, the oldest. The coronae are also variably cratered; of these, Elsinore and Arden Coronae have similar, intermediate crater frequencies, and may therefore have formed simultaneously. The Inverness Corona is the youngest of the major terrains. Periods of global expansion are implied by grabben formation that may have occurred both before and after the formation of the coronae.