Handy Bible Timeline
The ages of the patriarchs in the Old Testament vary slightly between the Septuagint, Samaritan and Masoretic text. The ages used for this timeline are from the Masoretic text which was used by Dr. Walter Brown in a chart he published in November 1981.
If you add up the length of time each of the patriarchs was alive before the next person (whether their son or distant relative) was born (shown in green), between Adam and Abraham, you come up with about 2,000 years. The possibility of gaps between the persons listed has no effect on the total time represented in the text. Since we know that Abraham lived almost 2,000 years before Christ, it's a real problem for people who insist that this earth has been around for longer than 6 - 10 thousand years.