In a sense, what is recorded in the pages of Scripture is a “birth certificate” for the earth and universe – a way of accurately identifying the birthdate of the universe and calculating the age based on that information.
What is this “birth certificate”? Genesis 1:1! The earth and universe were created at the beginning on the first day (Genesis 1:1-5). Then we pick up with the biblical genealogies especially those found in Genesis 5 and 11. In these genealogies, the age of the father is given at the time of the son’s birth: “Adam lived one hundred and thirty wears, and begot…Seth. Seth lived one hundred and five years, and begot Enosh….Enosh lived ninety years, and begot Cainan” (Genesis 53-9).
One need only to add these ages up – it’s not hard to do – to get an accurate estimate for the age of the earth. From Adam to Abraham, it’s approximately 2,000 years (technically the earth, which was made on day one, is five days older than Adam, who was made on day six, from Abraham to Christ is about 2,000 years and from Christ to today is roughly 2,000 years. Put all that together, and the simple math clearly implies the earth was created around 4,000 B.C.
(or 6,000 years ago from today). Believe it or not, most chronologists of the Old Testament, Jewish or Christian, have tabulated dates near this
for the past 2,000 years!
Quick Answers to Tough Questions by Bryan Osborne and Bodie Hodge