No other single method can determine the age of sediment deposited during the past 500 years. On the Namoi River there is a slight increase in phosphorus concentrations in about the last 30 years, but more measurements are needed to determine its significance. The dating technique is not confined to the sediments. Mud wasps are common worldwide and their nests, which set like concrete, may last thousands of years. Quartz grains from mud wasp nests were used to bracket the age of the paintings.
Rock art lying beneath a wasp's nest is older than the nest.
Where paint is superimposed on the remains of a wasps' nest, the painting is younger. Scientist also hope that because the technique can also be applied to young sediments that it will better enable us to understand the impact European settlement had on this island continent. This site is optimised for Netscape 2.01 or Internet Explorer 2.0. or higher.