The potassium-argon dating method has been used to measure a wide variety of ages. The potassium-argon age of some meteorites is as old as 4,500,000,000 years, and volcanic rocks as young as 20,000 years old have been measured by this method.

What is the useful time frame for potassium-argon dating?

Potassium-argon dating is accurate from 4.3 billion years (the age of the Earth) to about 100,000 years before the present. At 100,000 years, only 0.0053% of the potassium-40 in a rock would have decayed to argon-40, pushing the limits of present detection devices.

Why K Ar Cannot date younger rock?

Problems and Limitations of the K/Ar dating technique Alteration and high temperature can damage a rock/mineral lattice sufficiently to allow 40Ar* to be released. This can cause the calculated K/Ar age to be younger than the true age of the dated material.

What is the usable age range of K 40?

RADIOMETRIC TIME SCALEParent IsotopeStable Daughter ProductCurrently Accepted Half-Life ValuesUranium-235Lead-207704 million yearsThorium-232Lead-20814.0 billion yearsRubidium-87Strontium-8748.8 billion yearsPotassium-40Argon-401.25 billion years2 more rows•13 Jun 2001