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确定岩石的年龄岩石在形成时含有放射性同位素。例如,一些火成岩含钾-40,它衰变产生的氩被捕获在岩石里。通过测量岩石中钾-40和氩的比例,我们可以估计出岩石形成有多久。岩石形成的年代越古老,含有钾-40越少,氩越多。一个相似的方法是比较岩石中铀和铅的含量,这是因为放射性同位素铀衰变要经过漫
Determine Rock Age The rock contains radioactive isotopes when it is formed. For example, some igneous rocks contain potassium-40, which decays and is trapped in rocks. By measuring the proportion of potassium-40 in the rock and argon, we can estimate how long the rock has formed. The older the rock is formed, the less potassium-40 is contained and the more argon is present. A similar method is to compare the contents of uranium and lead in rocks. This is because radioactive uranium decay goes through