Coronae are geologically and geophysically important features on Venus, because they are thought to contribute to planetary heat loss. It is thus necessary to understand their role in space and time in the evolution of Venus. Detailed mapping of five coronae in Guinevere and Sedna Planitia illustrates that although previous models invoked initial uplift, not all coronae can be explained in such a simple way. We show that the formation of corona annuli can be multistaged and that the position of the annulus does not always coincide with the main topographic ridges and troughs that outline the feature. The magnitude and timing of volcanism are not necessarily the same at each corona, and coronae can have long and complex histories, in contrast with the stratigraphic relations suggested by other workers. We demonstrate that coronae do not all have the same relative ages with respect to adjacent units. These results suggest that corona formation was (is) not confined to a single time period in the history of Venus and that detailed mapping is a reliable method of establishing the relative timing of corona formation. ¿ 1998 American Geophysical Union