Geologic age dating methods sea captain dating website
Relative dating techniques provide geologists abundant evidence of the incredible vastness of geologic time and ancient age of many rocks and formations.However, in order to place absolute dates on the relative time scale, other dating methods must be considered.Absolute dating places events or rocks at a specific time.If a geologist claims to be younger than his or her co-worker, that is a relative age.These notes should be read along with the instructions under the individual terms in the body of the Thesaurus.Age-dating methods Age-dating methods are divided into two major groups: absolute-age and relative-age methods.Information specific to searching and the individual list topics is included, e.g., a section on age-dating methods begins on page xi.
The notes under Searching attempt to guide the searcher in the use of the list.
Rates of radioactive decay are constant and measured in terms of half-life, the time it takes half of a parent isotope to decay into a stable daughter isotope.
Some rock-forming minerals contain naturally occurring radioactive isotopes with very long half-lives unaffected by chemical or physical conditions that exist after the rock is formed.
Particularly useful are index fossils, geographically widespread fossils that evolved rapidly through time.
Crosscutting Relationships: Relative ages of rocks and events may also be determined using the law of crosscutting relationships, which states that geologic features such as igneous intrusions or faults are younger than the units they cut across.