Clearly, such huge time periods cannot be fitted into the Bible without compromising what the Bible says about the goodness of God and the origin of sin, death and suffering—the reason Jesus came into the world (See Six Days? He said, This only makes sense with a time-line beginning with the creation week thousands of years ago.
It makes no sense at all if man appeared at the end of billions of years.
Familiar to us as the black substance in charred wood, as diamonds, and the graphite in “lead” pencils, carbon comes in several forms, or isotopes.
One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or C ratio gets smaller.
Most scientists today believe that life has existed on the earth for billions of years.
This belief in long ages for the earth and the existence of life is derived largely from radiometric dating.
To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating.
Radiometric dating is largely done on rock that has formed from solidified lava.
These long time periods are computed by measuring the ratio of daughter to parent substance in a rock and inferring an age based on this ratio.
This age is computed under the assumption that the parent substance (say, uranium) gradually decays to the daughter substance (say, lead), so the higher the ratio of lead to uranium, the older the rock must be.
So, we have a “clock” which starts ticking the moment something dies.