Decay products of U-238 include thorium-234 (Th-234), protactinium ... uranium is not effectively transported in the food chain. Depleted uranium in the soil will be in an oxidized, soluble chemical ...

For example, about 1.5 percent of a quantity of Uranium 238 will decay to lead every 100 million years. By measuring the ratio of lead to uranium in a rock sample, its age can be determined.