As time passes, the amount of parent isotope in a rock decreases as the amount of daughter product increases.
By measuring the ratio of parent isotope to daughter product in a mineral and by knowing the half-life of the parent, in many cases you can calculate the absolute age of a rock. This process is called radiometric dating .
Today, scientists recognize that Earth has been shaped by two types of change: slow, everyday processes that takes place over millions
of years, and violent, unusual events such as the collision of a comet or asteroid about 65 million years ago that might have caused the extinction of the dinosaurs.
Section Check 3 Question 1 __________ age is the age in years of an object. A. Absolute B. Calculated C. Derived D. Relative NC: 5.01
Section Check 3 Answer The answer is A. Geologists use properties of atoms in specific materials to determine absolute age. NC: 5.01
Section Check 3 Question 2 What is meant by the term “half-life” of an isotope?
Section Check 3 Answer The half-life of an isotope is the time it takes for half of the atoms in the isotope to decay.
Section Check 3 Question 3 What information must you have in order to conduct radiometric dating? Answer You must have an isotope with an appropriately short or long half-life. You must also know the isotope’s half-life and be able to measure the ratio of parent isotope to daughter product.