Archaeological Dating
Significant progress has been made in this field of study since the
discovery of radioactivity and its properties. One application is
carbon14 dating. Recalling that all biologic organisms contain a
given concentration of carbon14, we can use this information to help
solve questions about when the organism died. It works like this..when
an organism dies it has a specific ratio by mass of carbon14 to
carbon12 incorporated in the cells of it's body. (The same ratio as in
the atmosphere.) At the moment of death, no new carbon14 containing
molecules are metabolized, therefore the ratio is at a maximum. After
death, the carbon14 to carbon12 ratio begins to decrease because
carbon14 is decaying away at a constant and predictable rate.
Remembering that the halflife of carbon14 is 5700 years, then after
5700 years half as much carbon14 remains within the organism.
Example : If an organism such as a tree contained 1 gram of carbon14
while it was living, then after 5700 years it would contain half that
amount, or 0.5 grams of carbon14.
This method of dating using carbon14 is only good for organisms or
artifacts that are biological by nature and on the order of tens of
thousands or years old.
What isotope would be increasing due to the decay of carbon14?
Could this method of dating be used to estimate the age of petroleum
deposits?
What human activities could alter the carbon14/carbon12 ratio?
