Its one of the fundamental standards of all the natural sciences. To understand the age of the earth provides us a reference to further comprehend the scale of earth history, the origins and development of all that now exists or has ever existed here. We can then extrapolate how things might take shape in the future.
Such understanding allows us to intelligently answer the most basic questions: "Where did I/we come from?", "Why are we here?", or "How did mountains rise?"
