Because argon is a gas, it should escape to the atmosphere due to the intense heat of the lavas. Of course, no geologist was present to test this assumption by observing ancient lavas when they cooled, but we can study modern lava flows. No specific location or expected age information was supplied to the laboratory. However, the samples were described as probably young with very little argon in them so as to ensure extra care was taken during the analytical work. Small ash eruption, Mt Ngauruhoe.
Different minerals have different colours.
All are embedded in a fine-grained matrix. Ar analyses are listed in Table 1 . The low 'age' samples were all processed by the laboratory in the same batch, suggesting a systematic lab problem. This ruled out a systematic lab error and confirmed that the low results were real. Clearly, the argon content varies greatly within these rocks.