Geoscience Reference
In-Depth Information
to break up into their daughter atoms; this amount of time is called
the half-life. Geologists can also measure how many parent and
daughter atoms are present in the small crystals that were formed
when the volcano erupted and can use these data to calculate the age
of the layer of volcanic ash and estimate how old fossils in nearby rock
layers are. Sometimes rock layers that can be dated by this method of
radioactive decay do not actually contain fossils. Nonetheless, if the
fossils from other rock layers in the stratigraphic section are above the
dated laver, we know that they are younger, and if the fossils are
below the dated layer, we know that they are older.
These methods of radiometric age estimation are based on the
same process of radioactive decay utilized in the carbon-14 technique
for dating ancient human remains and artifacts. The carbon-14 tech-
nique is not applicable for dating rocks and fossils older than about
Diagram showing basic
concept of radiometric
dating.
