Pictures on radioactive dating
The natural occurrence of radioactive atoms thus seems to confirm the age of the solar system.
(3) Often several different parent-daughter pairs give concordant (similar) ages for a given rock or mineral.
(2) Geochemistry suggests alternate time interpretations for the parent-daughter ratios.
– (a) Radiometric ages for some minerals may not give the time of emplacement of the volcanic or granitic rock because the minerals were formed earlier and the emplaced magma was not hot enough to melt them.
– Perhaps it is mainly concordant dates that get published and discordant dates are ignored.
Following are three of the many reasons that scientists put confidence in radiometric dates: (1) Decay rates appear to be constant.
[Any atom found in nature with a shorter half-life, such as carbon-14 or radon, is being produced by on-going nuclear reactions.] The 450 million-year value is significant because it is one tenth the estimated age of the solar system.
After ten half-lives the number of parent atoms decreases by a factor of about a thousand, and it is generally accepted that the number of parent atoms remaining in nature would be negligible.
In most cases, these rocks are not fossil-containing sedimentary rocks, but are volcanic, granitic, or metamorphic.
These inorganic methods date fossil material only by association and give ages of millions or billions of years.