Some of the atoms eventually change from one element to another by a process called radioactive decay.If there are a lot of atoms of the original element, called the parent element, the atoms decay to another element, called the daughter element, at a predictable rate.He was employed at Caltech's Division of Geological & Planetary Sciences at the time of writing the first edition.

Rocks are made up of many individual crystals, and each crystal is usually made up of at least several different chemical elements such as iron, magnesium, silicon, etc.Radiometric dating techniques indicate that the Earth is thousands of times older than that--approximately four and a half billion years old.Many Christians accept this and interpret the Genesis account in less scientifically literal ways.Most processes that we are familiar with are like sand in an hourglass.In exponential decay the amount of material decreases by half during each half-life.