Radiometric dating isn't the only method of determining the age of rocks.
Based on the analysis of these samples, scientists estimate that the Earth itself is about 4. With absolute age dating, you get a real age in actual years. The half-life of carbon is only 5, years, so carbon dating is only effective on samples that are less than 50, years old. Secure Server - We value your privacy. The half-life of carbon 14, for example, is 5, years. While the oldest known rocks on Earth are about 3. This rate of decay is called a half-life.