Problems determining relative and absolute ages using the small crater population

► We count small craters on both young and old surfaces using LROC and Kaguya data. ► Craters in 2 diameter ranges are counted for each counting area and then compared. ► Discrepancies occur in the results and the contamination of secondaries is one reason. ► Steep upturns in size distributions are caused by secondaries but not primaries. ► Lunar and martian small primaries have flat slopes like the Population 2 craters.