Thus, the older a rock is, the larger the number of daughter elements and the smaller the number of parent elements are found in the rock. As shown in the diagram above, uranium is trapped in a newly formed rock. As the rock ages, more and more of the uranium changes into lead. The age of the rock in years can be found by measuring the rate at which a parent element decays and then measuring the ratio of parent element to daughter element in the rock.
More recently, we've used other methods to associate actual dates with different rock layers, thus linking geologic time (a relative method) with. Everyone knows geologists love rocks, but when we talk about dating them, we're not talking about going to a fancy restaurant and ordering a nice pasta dish. The mineral zircon serves as a tiny time capsule, recording geologic events-it's “Depending on the history of the rock, we can date things nowadays down to.