Potassium 40 dating rocks

31-Dec-2015 08:05

Variations in this data may point to errors anywhere in the process, which is why all the steps of preparation are recorded in detail.

K-Ar analyses cost several hundred dollars per sample and take a week or two.

The potassium-argon (K-Ar) isotopic dating method is especially useful for determining the age of lavas.

Developed in the 1950s, it was important in develping plate tectonics and in calibrating the geologic time scale.

Rock samples are recorded, marked, sealed and kept free of contamination and excessive heat on the way to the lab.The site also must be geologically meaningful, clearly related to fossil-bearing rocks or other features that need a good date to join the big story.Lava flows that lie above and below rock beds with ancient human fossils are a good—and true—example.Finally the argon atoms are counted in a mass spectrometer, a machine with its own complexities.Three argon isotopes are measured: Ar is determined by comparison to it.

Rock samples are recorded, marked, sealed and kept free of contamination and excessive heat on the way to the lab.The site also must be geologically meaningful, clearly related to fossil-bearing rocks or other features that need a good date to join the big story.Lava flows that lie above and below rock beds with ancient human fossils are a good—and true—example.Finally the argon atoms are counted in a mass spectrometer, a machine with its own complexities.Three argon isotopes are measured: Ar is determined by comparison to it.The mineral sanidine, the high-temperature form of potassium feldspar, is the most desirable.