Numerical Geologic Time - Calculation
A granite contains zircon crystals with 175 billion 235U atoms and 1225 billion 207Pb atoms.
The half-life for 235U-to-207Pb decay is 704 million years. How old is the granite?
Hint: In order to solve this problem, you have to calculate the total number of parent and
daughter atoms (equaling the original number of parent atoms when the rock formed) and
then figure out how many half-lives have gone by until the current number of parent atoms
was reached (by repeatedly dividing the original number by 2). The final step is to multiply
this number of half-lives with the years that correspond to one half-life. - List all the steps in
your answer.