Öz Sinciairs’s method of separation of statisâcal populations is successfully applied on numeri- cal stream sediment data (hot extractable lead data) from the Belgian Ardennes. The application showed that the data consisted of one background (values less than 60 ppm) and two anomalous population (a) between 60 and 390 ppm and (b) values greater than 390 ppm. Samples represent- ing these populations are shown with different symbols on a map (discrete map) so that delineat- ion of the anomalous areas is possible on the map.