Metamorphic rocks may also be radiometrically dated.
However, radiometric dating generally yields the age of metamorphism, not the age of the original rock.
Half-lives of these isotopes and the parent-to-daughter ratio in a given rock sample can be measured, then a relatively simple calculation yields the absolute (radiometric) date at which the parent began to decay, i.e., the age of the rock.
Of the three basic rock types, igneous rocks are most suited for radiometric dating.
For example, shells, wood, and other material found in the shoreline deposits of Utah’s prehistoric Lake Bonneville have yielded absolute dates using this method.
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.Determining the Age of Rocks and Fossils, University of California, Berkeley. This 9-12-grade activity introduces students to age dating with exercises using relative and absolute dating. Links to various activities and lesson plans concerning relative and absolute dating. Content information about absolute and relative dating methods used by the U. 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.Simply stated, each bed in a sequence of sedimentary rocks (or layered volcanic rocks) is younger than the bed below it and older than the bed above it.This law follows two basic assumptions: (1) the beds were originally deposited near horizontal, and (2) the beds were not overturned after their deposition.Long before geologists tried to quantify the age of the Earth they developed techniques to determine which geologic events preceded another, what are termed "relative age” relationships.These techniques were first articulated by Nicolas Steno, a Dane living in the Medici court of Italy in the 17th C.If a geologist claims to be 45 years old, that is an absolute age.Superposition: The most basic concept used in relative dating is the law of superposition.