Elements used in absolute dating
Many isotopes have been studied, probing a wide range of time scales.
C and counting the amount of each) allows one to date the death of the once-living things.
Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.
These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.
So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.
Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium.
Third, magnetism in rocks can be used to estimate the age of a fossil site.Relative dating puts geologic events in chronological order without requiring that a specific numerical age be assigned to each event.Second, it is possible to determine the numerical age for fossils or earth materials.However, by itself a fossil has little meaning unless it is placed within some context.The age of the fossil must be determined so it can be compared to other fossil species from the same time period.