Final answer:
Clair Patterson provided evidence that heightened lead levels in the environment were not natural by comparing historical and modern data from ocean waters, ice cores, and human bone samples, showing increased lead coinciding with industrial activity.
Step-by-step explanation:
Clair Patterson used several lines of evidence to argue that the high levels of lead in the environment were not natural. One key evidence was the comparison of lead levels in deep ocean waters, which reflected the natural state, to those in the surface waters and atmosphere, which were significantly higher. Additionally, Patterson examined ice core samples from Greenland and Antarctica, finding a large increase in lead concentrations that coincided with the industrial revolution and the increased use of leaded gasoline.
Patterson's research also involved historical data analysis of lead in human tissues over time. The examination of pre-industrial human bones showed much lower lead content compared to modern samples. This historical comparison provided compelling evidence that the rise in environmental lead was a result of industrial practices rather than natural occurrences.