How does radioactive decay give absolute dates to events in the geologic past?

Most absolute dates for rocks are obtained with radiometric methods. These use radioactive minerals in rocks as geological clocks. ... Each original isotope, called the parent, gradually decays to form a new isotope, called the daughter. Each isotope is identified with what is called a 'mass number'.

Explanation:

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heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.