K ar dating method
The isotopes the KAr system relies on are Potassium (K) and Argon (Ar).
Each half-life is 1.3 billion years, so after 3.9 billion years (three half-lives) 12.5% of the original 40K will remain.This is determined by drawing a horizontal line from 0.95 to the decay curve line, and then a vertical line from there to the time axis.[SE] K-Ar is just one of many isotope-pairs that are useful for dating geological materials.C) can be applied to many geological materials, including sediments and sedimentary rocks, but the materials in question must be younger than 60 ka.Fragments of wood incorporated into young sediments are good candidates for carbon dating, and this technique has been used widely in studies involving late Pleistocene glaciers and glacial sediments.
The red-blue bars represent 40K and the green-yellow bars represent 40Ar.