Determining Age Crossword

This printable crossword puzzle on the topic of Rocks & Minerals has 10 clues. Answers range from 8 to 18 letters long. This crossword is also available to download as a Microsoft Word document or a PDF.

Does not indicate the rocks exact age.
Only occurs in rocks layers of a particular age
C14, converts to a daughter isotope.
The rocks age in exact years.
The that younger rocks are on top, older rocks are on the top.
N14, used to be a parent isotope
How long it takes half the parent mass to convert daughter isotope.
Useful in dating organic material less than 70,000 years old.
Measures concentrations of the original radioactive isotope and of the newly formed isotope.
A fossil only found in rock dating 180-206 MYA