In venusian plains, impact craters without extensive low backscatter ejecta deposits are more likely to have low backscatter floors, be embayed by volcanic deposits, and exhibit fractures as compared to craters with extensive low backscatter ejecta. We interpret these trends as evidence of ongoing degradation of low backscatter ejecta by aeolian activity, weathering, and volcanism. Using a crater age sequence based on extent of preservation of low backscatter ejecta, together with Monte Carlo simulations, we find that tectonic activity has extended over a longer time period than volcanism.