However, the age of each fossil primate needs to be determined so that fossils of the same age found in different parts of the world and fossils of different ages can be compared.
There are three general approaches that allow scientists to date geological materials and answer the question: "How old is this fossil?
The age of the fossil must be determined so it can be compared to other fossil species from the same time period.
Understanding the ages of related fossil species helps scientists piece together the evolutionary history of a group of organisms.
Layers that cut across other layers are younger than the layers they cut through (principle of cross-cutting relationships).
The principle of superposition builds on the principle of original horizontality.
Third, magnetism in rocks can be used to estimate the age of a fossil site.
This is the principle of cross-cutting relationships.The principle states that any geologic features that cut across strata must have formed after the rocks they cut through (Figures 2 and 3).According to the principle of original horizontality, these strata must have been deposited horizontally and then titled vertically after they were deposited.Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.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.The study of strata is called stratigraphy, and using a few basic principles, it is possible to work out the relative ages of rocks.