In some rocks the grains are badly cracked.Could you explain to me why this dating method gives the wrong?

Question

age for these rocks?

scientists can date rocks by measuring the amount of argon inside the rock grains. The argon is formed when patssium atoms decay.

Answer 1

Argon is a gas at most temperatures and pressures, and badly cracked grains will allow the argon from potassium decay to escape into the atmosphere, much like CO2 escapes from an open bottle of soda.

More information on potassium/argon dating is found at:

http://hypertextbook.com/physics/modern/half-life/

Answer 2

Argon is a gas. If physical damage lets the argon escape, the apparent date could be wrong.