Radioisotopic dating parent daughter
This has enabled workers to define a for each radioisotope, the period required for one-half of the original parent population to decay to its stable daughter product.
By combining knowledge gained using both relative and absolute dating processes geologists have been able to produce the geologic time scale.The Table of Radionuclides documents the naturally-occurring radioisotopes.Some isotopes decay and immediately produce a stable daughter product.Unlike relative time, absolute time assigns specific ages to events or formations and is typically recorded in years before present.This process requires much more sophisticated chemical analysis and, although other processes have been developed, often utilizes the decay rates of radioactive isotopes to determine the age of a given material.With out individual time stamps the process of dating these structures could become extremely difficult.
To deal with many of these problems geologists utilize two types of geologic time: relative time and absolute time.
When an isotope emits an alpha particle, the resultant daughter product has an atomic number two units less than its parent's atomic number, and an atomic weight four units less than its parent's atomic weight.
When an isotope emits a beta particle, it decays to a daughter with an atomic number one unit greater and an essentially unchanged atomic weight.
The sample must have originally contained 4 units of parent material, and 25% of the parent material (U-235) remains.
Examination of the curve above shows that time equivalent to two half-lives have passed, or approximately 1.4 billion years.
With this in mind geologist have long known that the deeper a sedimentary rock layer is the older it is, but how old?