R.E. Arvidson, R.E. Grimm, R.J. Phillips, G.G. Schaber, E.M. Shoemaker, "On the nature and rate of resurfacing of Venus," Geophysical Research Letters, 17:1385-88, 1990.
Raymond E. Arvidson (Washington University, St. Louis): "The size-frequency distribution, abundance, and locations of impact craters provide key pieces of information for understanding how planets are resurfaced.
"Based on the average size frequency distribution, we know that volcanism and tectonism have removed Venusian craters that are older than several hundred million years of age. But does this result mean that resurfacing effectively stopped then?
"We think not. Rather, we presented a hypothesis that Venus has ongoing volcanic and tectonic activity that occurs randomly in space and time. Areas recently affected should be devoid of craters, whereas regions that have been quiescent for a long time should have an excess of craters, relative to the global average.
"This work has been verified by analyses of Magellan radar...