Wiens has a Ph D in Physics, with a minor in Geology.
His Ph D thesis was on isotope ratios in meteorites, including surface exposure dating.
He was employed at Caltech's Division of Geological & Planetary Sciences at the time of writing the first edition.
He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.
Following death, however, no new carbon is consumed.
Progressively through time, the carbon-14 atoms decay and once again become nitrogen-14.
Since 1955 the estimate for the age of the Earth has been based on the assumption that certain meteorite lead isotope ratios are equivalent to the primordial lead isotope ratios on Earth.
In 1972 this assumption was shown to be highly questionable.
One half-life is the amount of time required for of the original atoms in a sample to decay.
organisms, geologists employ a variety of techniques.
These include some that establish a relative chronology in which occurrences can be placed in the correct sequence relative to one another or to some known succession of events.
For example, the presence of recycled bricks at an archaeological site indicates the sequence in which the structures were built.
Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence.