Radiogenic isotopes are isotopes that are formed through the process of radioactive decay. When unstable parent isotopes decay, they transform into stable or unstable daughter isotopes over time. This process occurs naturally in various elements, such as uranium and thorium, and is used in fields like geology and archaeology to date materials and understand the age of rocks and fossils. These isotopes are important for studying the Earth's history and processes. For example, the decay of carbon-14 is commonly used in radiocarbon dating to determine the age of organic materials. By measuring the ratio of parent to daughter isotopes, scientists can gain insights into the timing of geological events and the evolution of life on Earth.