The age of fossils is most important. Darwin knew it would take a long time for evolution to have created the variety of species that exists today. However, he had no idea how old the earth really was and that presented him with a large problem.
Therefore, it is important to establish that the earth is very old; 4.5 BILLION years old to be exact. And, the earth is a relative newcomer to the universe which is 13.5 BILLION years old.
Because the dating of things is so important to acccepting evolution, I spend considerable time in the following sections on dating techniques. How these ages are determined and proved is the topic of these next pages. The techniques used to determine the age of very old rocks, fossils and artifacts are very accurate and cross validated.
Now, I don't understand a bit of the science of the techniques. What I do understand is that the principles used in the dating techniques are taught in introductory Physics, Chemistry, Astronomy, and Cosmology courses. They are basic and fundamental axioms of the disciplines.They corroborate each other. There is no question among the legitimate scientific community, that these techniques are accurate.